From 2eff8326698cfbfc40878a8f7292c0e7847527bc Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sat, 9 Jan 2021 20:48:18 +0100
Subject: [PATCH 01/37] Add --rules switch to the CLI

---
 spec/ameba/cli/cmd_spec.cr | 10 ++++++++++
 src/ameba/cli/cmd.cr       | 20 ++++++++++++++++++--
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/spec/ameba/cli/cmd_spec.cr b/spec/ameba/cli/cmd_spec.cr
index f44ff6c6b..def5b6bff 100644
--- a/spec/ameba/cli/cmd_spec.cr
+++ b/spec/ameba/cli/cmd_spec.cr
@@ -42,6 +42,16 @@ module Ameba::Cli
         c.except.should eq %w(RULE1 RULE2)
       end
 
+      it "defaults rules? flag to false" do
+        c = Cli.parse_args %w(file.cr)
+        c.rules?.should eq false
+      end
+
+      it "accepts --rules flag" do
+        c = Cli.parse_args %w(--rules)
+        c.rules?.should eq true
+      end
+
       it "defaults all? flag to false" do
         c = Cli.parse_args %w(file.cr)
         c.all?.should eq false
diff --git a/src/ameba/cli/cmd.cr b/src/ameba/cli/cmd.cr
index 42778da28..e34ba2415 100644
--- a/src/ameba/cli/cmd.cr
+++ b/src/ameba/cli/cmd.cr
@@ -14,6 +14,10 @@ module Ameba::Cli
     configure_formatter(config, opts)
     configure_rules(config, opts)
 
+    if opts.rules?
+      print_rules(config)
+    end
+
     runner = Ameba.run(config)
 
     if location = opts.location_to_explain
@@ -34,6 +38,7 @@ module Ameba::Cli
     property except : Array(String)?
     property location_to_explain : NamedTuple(file: String, line: Int32, column: Int32)?
     property fail_level : Severity?
+    property? rules = false
     property? all = false
     property? colors = true
     property? without_affected_code = false
@@ -44,7 +49,8 @@ module Ameba::Cli
       parser.banner = "Usage: ameba [options] [file1 file2 ...]"
 
       parser.on("-v", "--version", "Print version") { print_version }
-      parser.on("-h", "--help", "Show this help") { show_help parser }
+      parser.on("-h", "--help", "Show this help") { print_help(parser) }
+      parser.on("-r", "--rules", "Show all available rules") { opts.rules = true }
       parser.on("-s", "--silent", "Disable output") { opts.formatter = :silent }
       parser.unknown_args do |f|
         if f.size == 1 && f.first =~ /.+:\d+:\d+/
@@ -145,8 +151,18 @@ module Ameba::Cli
     exit 0
   end
 
-  private def show_help(parser)
+  private def print_help(parser)
     puts parser
     exit 0
   end
+
+  private def print_rules(config)
+    config.rules.each do |rule|
+      puts \
+        "#{rule.name.colorize(:white)} " \
+        "[#{rule.severity.symbol.to_s.colorize(:green)}] - " \
+        "#{rule.description.colorize(:dark_gray)}"
+    end
+    exit 0
+  end
 end

From 19c370aee06a6c7bbaec7c42b1d3331f77256fc5 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Mon, 11 Jan 2021 19:13:58 +0100
Subject: [PATCH 02/37] Misc refactors (#180)

* Optimize Severity#symbol

* Remove empty else branches

* Optimize map+compact/flatten calls

* Misc stylistic refactors
---
 src/ameba/ast/branchable.cr                 |  3 +--
 src/ameba/ast/flow_expression.cr            |  2 --
 src/ameba/ast/scope.cr                      | 10 +++----
 src/ameba/cli/cmd.cr                        | 29 +++++++++++++--------
 src/ameba/config.cr                         | 15 ++++++-----
 src/ameba/formatter/dot_formatter.cr        |  9 ++++---
 src/ameba/formatter/explain_formatter.cr    | 15 +++++------
 src/ameba/formatter/flycheck_formatter.cr   |  2 +-
 src/ameba/formatter/todo_formatter.cr       | 18 ++++++-------
 src/ameba/formatter/util.cr                 |  6 ++---
 src/ameba/glob_utils.cr                     |  4 +--
 src/ameba/inline_comments.cr                |  6 +++--
 src/ameba/rule/base.cr                      |  8 +++---
 src/ameba/rule/lint/percent_array.cr        |  4 ---
 src/ameba/rule/lint/redundant_with_index.cr |  2 --
 src/ameba/rule/style/redundant_begin.cr     |  4 +--
 src/ameba/runner.cr                         |  6 ++---
 src/ameba/severity.cr                       |  8 ++++--
 src/ameba/source.cr                         | 25 +++++++-----------
 src/ameba/tokenizer.cr                      |  9 +------
 20 files changed, 87 insertions(+), 98 deletions(-)

diff --git a/src/ameba/ast/branchable.cr b/src/ameba/ast/branchable.cr
index 2495dbb2a..4bf9819ef 100644
--- a/src/ameba/ast/branchable.cr
+++ b/src/ameba/ast/branchable.cr
@@ -37,8 +37,7 @@ module Ameba::AST
 
     # Returns true if this node or one of the parent branchables is a loop, false otherwise.
     def loop?
-      return true if loop?(node)
-      parent.try(&.loop?) || false
+      loop?(node) || parent.try(&.loop?) || false
     end
   end
 end
diff --git a/src/ameba/ast/flow_expression.cr b/src/ameba/ast/flow_expression.cr
index 6b2149622..8c80eb531 100644
--- a/src/ameba/ast/flow_expression.cr
+++ b/src/ameba/ast/flow_expression.cr
@@ -59,8 +59,6 @@ module Ameba::AST
         end
       when Crystal::BinaryOp
         unreachable_nodes << current_node.right if flow_expression?(current_node.left, in_loop?)
-      else
-        # nop
       end
 
       unreachable_nodes
diff --git a/src/ameba/ast/scope.cr b/src/ameba/ast/scope.cr
index 3627ef73e..a6a8ee081 100644
--- a/src/ameba/ast/scope.cr
+++ b/src/ameba/ast/scope.cr
@@ -117,8 +117,8 @@ module Ameba::AST
 
     # Returns true instance variable assinged in this scope.
     def assigns_ivar?(name)
-      arguments.find { |arg| arg.name == name } &&
-        ivariables.find { |var| var.name == "@#{name}" }
+      arguments.find(&.name.== name) &&
+        ivariables.find(&.name.== "@#{name}")
     end
 
     # Returns true if and only if current scope represents some
@@ -137,13 +137,13 @@ module Ameba::AST
     def references?(variable : Variable)
       variable.references.any? do |reference|
         reference.scope == self ||
-          inner_scopes.any?(&.references? variable)
+          inner_scopes.any?(&.references?(variable))
       end || variable.used_in_macro?
     end
 
     # Returns true if current scope is a def, false if not.
     def def?
-      node.is_a? Crystal::Def
+      node.is_a?(Crystal::Def)
     end
 
     # Returns true if this scope is a top level scope, false if not.
@@ -173,7 +173,7 @@ module Ameba::AST
     # the same Crystal node as `@node`.
     def eql?(node)
       node == @node &&
-        !node.location.nil? &&
+        node.location &&
         node.location == @node.location
     end
   end
diff --git a/src/ameba/cli/cmd.cr b/src/ameba/cli/cmd.cr
index e34ba2415..7b9e6bae3 100644
--- a/src/ameba/cli/cmd.cr
+++ b/src/ameba/cli/cmd.cr
@@ -72,12 +72,12 @@ module Ameba::Cli
 
       parser.on("--only RULE1,RULE2,...",
         "Run only given rules (or groups)") do |rules|
-        opts.only = rules.split ","
+        opts.only = rules.split(',')
       end
 
       parser.on("--except RULE1,RULE2,...",
         "Disable the given rules (or groups)") do |rules|
-        opts.except = rules.split ","
+        opts.except = rules.split(',')
       end
 
       parser.on("--all", "Enables all available rules") do
@@ -90,7 +90,8 @@ module Ameba::Cli
         opts.config = ""
       end
 
-      parser.on("--fail-level SEVERITY", "Change the level of failure to exit. Defaults to Convention") do |level|
+      parser.on("--fail-level SEVERITY",
+        "Change the level of failure to exit. Defaults to Convention") do |level|
         opts.fail_level = Severity.parse(level)
       end
 
@@ -113,13 +114,13 @@ module Ameba::Cli
   end
 
   private def configure_rules(config, opts)
-    if only = opts.only
-      config.rules.map! { |r| r.enabled = false; r }
+    case
+    when only = opts.only
+      config.rules.map! &.tap(&.enabled = false)
       config.update_rules(only, enabled: true)
-    elsif opts.all?
-      config.rules.map! { |r| r.enabled = true; r }
+    when opts.all?
+      config.rules.map! &.tap(&.enabled = true)
     end
-
     config.update_rules(opts.except, enabled: false)
   end
 
@@ -127,7 +128,8 @@ module Ameba::Cli
     if name = opts.formatter
       config.formatter = name
     end
-    config.formatter.config[:without_affected_code] = opts.without_affected_code?
+    config.formatter.config[:without_affected_code] =
+      opts.without_affected_code?
   end
 
   private def configure_explain_opts(loc, opts)
@@ -138,10 +140,15 @@ module Ameba::Cli
   end
 
   private def parse_explain_location(arg)
-    location = arg.split(":", remove_empty: true).map &.strip
+    location = arg.split(':', remove_empty: true).map! &.strip
     raise ArgumentError.new unless location.size === 3
+
     file, line, column = location
-    {file: file, line: line.to_i, column: column.to_i}
+    {
+      file:   file,
+      line:   line.to_i,
+      column: column.to_i,
+    }
   rescue
     raise "location should have PATH:line:column format"
   end
diff --git a/src/ameba/config.cr b/src/ameba/config.cr
index 1ecbd3a8c..5bf0261ee 100644
--- a/src/ameba/config.cr
+++ b/src/ameba/config.cr
@@ -31,7 +31,6 @@ class Ameba::Config
     !lib
   )
 
-  setter formatter : Formatter::BaseFormatter?
   getter rules : Array(Rule::Base)
   property severity = Severity::Convention
 
@@ -66,7 +65,9 @@ class Ameba::Config
     @excluded = load_array_section(config, "Excluded")
     @globs = load_array_section(config, "Globs", DEFAULT_GLOBS)
 
-    self.formatter = load_formatter_name(config)
+    if formatter_name = load_formatter_name(config)
+      self.formatter = formatter_name
+    end
   end
 
   # Loads YAML configuration file by `path`.
@@ -84,7 +85,7 @@ class Ameba::Config
   end
 
   def self.formatter_names
-    AVAILABLE_FORMATTERS.keys.join("|")
+    AVAILABLE_FORMATTERS.keys.join('|')
   end
 
   # Returns a list of sources matching globs and excluded sections.
@@ -111,8 +112,8 @@ class Ameba::Config
   # config.formatter
   # ```
   #
-  def formatter
-    @formatter ||= Formatter::DotFormatter.new
+  property formatter : Formatter::BaseFormatter do
+    Formatter::DotFormatter.new
   end
 
   # Sets formatter by name.
@@ -138,7 +139,7 @@ class Ameba::Config
   # ```
   #
   def update_rule(name, enabled = true, excluded = nil)
-    index = @rules.index { |r| r.name == name }
+    index = @rules.index { |rule| rule.name == name }
     raise ArgumentError.new("Rule `#{name}` does not exist") unless index
 
     rule = @rules[index]
@@ -172,7 +173,7 @@ class Ameba::Config
 
   private def load_formatter_name(config)
     name = config["Formatter"]?.try &.["Name"]?
-    name ? name.to_s : nil
+    name.try(&.to_s)
   end
 
   private def load_array_section(config, section_name, default = [] of String)
diff --git a/src/ameba/formatter/dot_formatter.cr b/src/ameba/formatter/dot_formatter.cr
index 396069e53..54fe53ac9 100644
--- a/src/ameba/formatter/dot_formatter.cr
+++ b/src/ameba/formatter/dot_formatter.cr
@@ -35,14 +35,17 @@ module Ameba::Formatter
           next if issue.disabled?
           next if (location = issue.location).nil?
 
-          output << "#{location}\n".colorize(:cyan)
-          output << "[#{issue.rule.severity.symbol}] #{issue.rule.name}: #{issue.message}\n".colorize(:red)
+          output.puts location.colorize(:cyan)
+          output.puts \
+            "[#{issue.rule.severity.symbol}] " \
+            "#{issue.rule.name}: " \
+            "#{issue.message}".colorize(:red)
 
           if show_affected_code && (code = affected_code(source, location))
             output << code.colorize(:default)
           end
 
-          output << "\n"
+          output << '\n'
         end
       end
 
diff --git a/src/ameba/formatter/explain_formatter.cr b/src/ameba/formatter/explain_formatter.cr
index 6670245ba..9220ae3fa 100644
--- a/src/ameba/formatter/explain_formatter.cr
+++ b/src/ameba/formatter/explain_formatter.cr
@@ -4,9 +4,8 @@ module Ameba::Formatter
   # A formatter that shows the detailed explanation of the issue at
   # a specific location.
   class ExplainFormatter
-    LINE_BREAK = "\n"
-    HEADING    = "## "
-    PREFIX     = " "
+    HEADING = "## "
+    PREFIX  = " "
 
     include Util
 
@@ -65,19 +64,19 @@ module Ameba::Formatter
     end
 
     private def output_title(title)
-      output << HEADING.colorize(:yellow) << title.colorize(:yellow) << LINE_BREAK
-      output << LINE_BREAK
+      output << HEADING.colorize(:yellow) << title.colorize(:yellow) << '\n'
+      output << '\n'
     end
 
     private def output_paragraph(paragraph : String)
-      output_paragraph(paragraph.split(LINE_BREAK))
+      output_paragraph(paragraph.split('\n'))
     end
 
     private def output_paragraph(paragraph : Array(String))
       paragraph.each do |line|
-        output << PREFIX << line << LINE_BREAK
+        output << PREFIX << line << '\n'
       end
-      output << LINE_BREAK
+      output << '\n'
     end
   end
 end
diff --git a/src/ameba/formatter/flycheck_formatter.cr b/src/ameba/formatter/flycheck_formatter.cr
index 89423ff39..50d5de6ca 100644
--- a/src/ameba/formatter/flycheck_formatter.cr
+++ b/src/ameba/formatter/flycheck_formatter.cr
@@ -9,7 +9,7 @@ module Ameba::Formatter
           @mutex.synchronize do
             output.printf "%s:%d:%d: %s: [%s] %s\n",
               source.path, loc.line_number, loc.column_number, e.rule.severity.symbol,
-              e.rule.name, e.message.gsub("\n", " ")
+              e.rule.name, e.message.gsub('\n', " ")
           end
         end
       end
diff --git a/src/ameba/formatter/todo_formatter.cr b/src/ameba/formatter/todo_formatter.cr
index fd0b81000..88584d1d6 100644
--- a/src/ameba/formatter/todo_formatter.cr
+++ b/src/ameba/formatter/todo_formatter.cr
@@ -8,19 +8,20 @@ module Ameba::Formatter
 
     def finished(sources)
       super
-      issues = sources.map(&.issues).flatten
+
+      issues = sources.flat_map(&.issues)
       unless issues.any? { |issue| !issue.disabled? }
-        @output << "No issues found. File is not generated.\n"
+        @output.puts "No issues found. File is not generated."
         return
       end
 
-      if issues.any? { |issue| issue.syntax? }
-        @output << "Unable to generate TODO file. Please fix syntax issues.\n"
+      if issues.any?(&.syntax?)
+        @output.puts "Unable to generate TODO file. Please fix syntax issues."
         return
       end
 
       file = generate_todo_config issues
-      @output << "Created #{file.path}\n"
+      @output.puts "Created #{file.path}"
       file
     end
 
@@ -57,10 +58,9 @@ module Ameba::Formatter
     end
 
     private def rule_todo(rule, issues)
-      rule.excluded =
-        issues.map(&.location.try &.filename.try &.to_s)
-          .compact
-          .uniq!
+      rule.excluded = issues
+        .compact_map(&.location.try &.filename.try &.to_s)
+        .uniq!
 
       {rule.name => rule}.to_yaml
     end
diff --git a/src/ameba/formatter/util.cr b/src/ameba/formatter/util.cr
index 7219a67bb..26410313d 100644
--- a/src/ameba/formatter/util.cr
+++ b/src/ameba/formatter/util.cr
@@ -2,9 +2,9 @@ module Ameba::Formatter
   module Util
     def affected_code(source, location, max_length = 100, placeholder = " ...", prompt = "> ")
       line, column = location.line_number, location.column_number
-      affected_line = source.lines[line - 1]?
+      affected_line = source.lines[line - 1]?.presence
 
-      return if affected_line.nil? || affected_line.strip.empty?
+      return unless affected_line
 
       if affected_line.size > max_length && column < max_length
         affected_line = affected_line[0, max_length - placeholder.size - 1] + placeholder
@@ -14,7 +14,7 @@ module Ameba::Formatter
       position = column - (affected_line.size - stripped.size) + prompt.size
 
       String.build do |str|
-        str << prompt << stripped << "\n"
+        str << prompt << stripped << '\n'
         str << " " * (position - 1)
         str << "^".colorize(:yellow)
       end
diff --git a/src/ameba/glob_utils.cr b/src/ameba/glob_utils.cr
index a714f8851..b014bf389 100644
--- a/src/ameba/glob_utils.cr
+++ b/src/ameba/glob_utils.cr
@@ -22,10 +22,10 @@ module Ameba
     # ```
     #
     def expand(globs)
-      globs.map do |glob|
+      globs.flat_map do |glob|
         glob += "/**/*.cr" if File.directory?(glob)
         Dir[glob]
-      end.flatten.uniq!
+      end.uniq!
     end
 
     private def rejected_globs(globs)
diff --git a/src/ameba/inline_comments.cr b/src/ameba/inline_comments.cr
index cece57fec..7d1ec14d9 100644
--- a/src/ameba/inline_comments.cr
+++ b/src/ameba/inline_comments.cr
@@ -89,8 +89,10 @@ module Ameba
 
     private def line_disabled?(line, rule)
       return false unless directive = parse_inline_directive(line)
-      Action.parse?(directive[:action]).try(&.disable?) &&
-        (directive[:rules].includes?(rule.name) || directive[:rules].includes?(rule.group))
+      return false unless Action.parse?(directive[:action]).try(&.disable?)
+
+      directive[:rules].includes?(rule.name) ||
+        directive[:rules].includes?(rule.group)
     end
 
     private def commented_out?(line)
diff --git a/src/ameba/rule/base.cr b/src/ameba/rule/base.cr
index c895499a2..de4c363ff 100644
--- a/src/ameba/rule/base.cr
+++ b/src/ameba/rule/base.cr
@@ -95,7 +95,7 @@ module Ameba::Rule
     def excluded?(source)
       excluded.try &.any? do |path|
         source.matches_path?(path) ||
-          Dir.glob(path).any? { |glob| source.matches_path? glob }
+          Dir.glob(path).any? { |glob| source.matches_path?(glob) }
       end
     end
 
@@ -123,11 +123,11 @@ module Ameba::Rule
     end
 
     protected def self.rule_name
-      name.gsub("Ameba::Rule::", "").gsub("::", "/")
+      name.gsub("Ameba::Rule::", "").gsub("::", '/')
     end
 
     protected def self.group_name
-      rule_name.split("/")[0...-1].join("/")
+      rule_name.split('/')[0...-1].join('/')
     end
 
     protected def self.subclasses
@@ -157,7 +157,7 @@ module Ameba::Rule
     def self.parsed_doc
       source = File.read(path_to_source_file)
       nodes = Crystal::Parser.new(source).tap(&.wants_doc = true).parse
-      type_name = rule_name.split("/").last?
+      type_name = rule_name.split('/').last?
       DocFinder.new(nodes, type_name).doc
     end
 
diff --git a/src/ameba/rule/lint/percent_array.cr b/src/ameba/rule/lint/percent_array.cr
index 0f1d3de82..afdf02230 100644
--- a/src/ameba/rule/lint/percent_array.cr
+++ b/src/ameba/rule/lint/percent_array.cr
@@ -49,8 +49,6 @@ module Ameba::Rule::Lint
             issue_for start_token.not_nil!, issue.not_nil!
           end
           issue = start_token = nil
-        else
-          # nop
         end
       end
     end
@@ -61,8 +59,6 @@ module Ameba::Rule::Lint
         check_array_entry entry, string_array_unwanted_symbols, "%w"
       when .starts_with? "%i"
         check_array_entry entry, symbol_array_unwanted_symbols, "%i"
-      else
-        # nop
       end
     end
 
diff --git a/src/ameba/rule/lint/redundant_with_index.cr b/src/ameba/rule/lint/redundant_with_index.cr
index f67766d6d..d9c646f39 100644
--- a/src/ameba/rule/lint/redundant_with_index.cr
+++ b/src/ameba/rule/lint/redundant_with_index.cr
@@ -42,8 +42,6 @@ module Ameba::Rule::Lint
         report source, node, "Remove redundant with_index"
       when "each_with_index"
         report source, node, "Use each instead of each_with_index"
-      else
-        # nop
       end
     end
 
diff --git a/src/ameba/rule/style/redundant_begin.cr b/src/ameba/rule/style/redundant_begin.cr
index bfb028a63..1318bb4b2 100644
--- a/src/ameba/rule/style/redundant_begin.cr
+++ b/src/ameba/rule/style/redundant_begin.cr
@@ -76,8 +76,6 @@ module Ameba::Rule::Style
         redundant_begin_in_handler?(source, body, node)
       when Crystal::Expressions
         redundant_begin_in_expressions?(body)
-      else
-        # nop
       end
     end
 
@@ -88,7 +86,7 @@ module Ameba::Rule::Style
     private def redundant_begin_in_handler?(source, handler, node)
       return false if begin_exprs_in_handler?(handler) || inner_handler?(handler)
 
-      code = node_source(node, source.lines).try &.join("\n")
+      code = node_source(node, source.lines).try &.join('\n')
       def_redundant_begin? code if code
     rescue
       false
diff --git a/src/ameba/runner.cr b/src/ameba/runner.cr
index ece391877..e742dab2c 100644
--- a/src/ameba/runner.cr
+++ b/src/ameba/runner.cr
@@ -50,7 +50,6 @@ module Ameba
           .find &.name.==(Rule::Lint::UnneededDisableDirective.rule_name)
     end
 
-    # :nodoc:
     protected def initialize(@rules, @sources, @formatter, @severity)
     end
 
@@ -80,9 +79,8 @@ module Ameba
         end
       end
 
-      channels.each do |c|
-        e = c.receive
-        raise e unless e.nil?
+      channels.each do |chan|
+        chan.receive.try { |e| raise e }
       end
 
       self
diff --git a/src/ameba/severity.cr b/src/ameba/severity.cr
index 917cf4e98..3b0e4327c 100644
--- a/src/ameba/severity.cr
+++ b/src/ameba/severity.cr
@@ -9,8 +9,12 @@ module Ameba
     # ```
     # Severity::Warning.symbol # => 'W'
     # ```
-    def symbol
-      to_s[0]
+    def symbol : Char
+      case self
+      in Error      then 'E'
+      in Warning    then 'W'
+      in Convention then 'C'
+      end
     end
 
     # Creates Severity by the name.
diff --git a/src/ameba/source.cr b/src/ameba/source.cr
index 3fd8d751d..70d38627a 100644
--- a/src/ameba/source.cr
+++ b/src/ameba/source.cr
@@ -11,10 +11,6 @@ module Ameba
     # Crystal code (content of a source file).
     getter code : String
 
-    @lines : Array(String)?
-    @ast : Crystal::ASTNode?
-    @fullpath : String?
-
     # Creates a new source by `code` and `path`.
     #
     # For example:
@@ -24,7 +20,7 @@ module Ameba
     # Ameba::Source.new File.read(path), path
     # ```
     #
-    def initialize(@code : String, @path = "")
+    def initialize(@code, @path = "")
     end
 
     # Returns lines of code splitted by new line character.
@@ -38,9 +34,7 @@ module Ameba
     # source.lines # => ["a = 1", "b = 2"]
     # ```
     #
-    def lines
-      @lines ||= @code.split("\n")
-    end
+    getter lines : Array(String) { code.split('\n') }
 
     # Returns AST nodes constructed by `Crystal::Parser`.
     #
@@ -49,16 +43,15 @@ module Ameba
     # source.ast
     # ```
     #
-    def ast
-      @ast ||=
-        Crystal::Parser.new(code)
-          .tap { |parser| parser.wants_doc = true }
-          .tap { |parser| parser.filename = @path }
-          .parse
+    getter ast : Crystal::ASTNode do
+      Crystal::Parser.new(code)
+        .tap(&.wants_doc = true)
+        .tap(&.filename = path)
+        .parse
     end
 
-    def fullpath
-      @fullpath ||= File.expand_path @path
+    getter fullpath : String do
+      File.expand_path(path)
     end
 
     # Returns true if *filepath* matches the source's path, false if it does not.
diff --git a/src/ameba/tokenizer.cr b/src/ameba/tokenizer.cr
index 070e5b552..e79d12cb4 100644
--- a/src/ameba/tokenizer.cr
+++ b/src/ameba/tokenizer.cr
@@ -53,8 +53,7 @@ module Ameba
       false
     end
 
-    private def run_normal_state(lexer, break_on_rcurly = false,
-                                 &block : Crystal::Token -> _)
+    private def run_normal_state(lexer, break_on_rcurly = false, &block : Crystal::Token -> _)
       loop do
         token = @lexer.next_token
         block.call token
@@ -68,8 +67,6 @@ module Ameba
           break
         when :"}"
           break if break_on_rcurly
-        else
-          # go on
         end
       end
     end
@@ -86,8 +83,6 @@ module Ameba
           run_normal_state lexer, break_on_rcurly: true, &block
         when :EOF
           break
-        else
-          # go on
         end
       end
     end
@@ -102,8 +97,6 @@ module Ameba
           break
         when :EOF
           break
-        else
-          # go on
         end
       end
     end

From c4d34d74d86bdd978b5ae34136d6c980ab7e1cda Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Tue, 12 Jan 2021 16:20:43 +0100
Subject: [PATCH 03/37] Add support for showing code context lines (#181)

* Add support for showing code context lines

* Show context lines only in ExplainFormatter

* Add spec coverage for context_lines option
---
 spec/ameba/formatter/util_spec.cr        | 33 ++++++++++-
 src/ameba/formatter/explain_formatter.cr |  2 +-
 src/ameba/formatter/util.cr              | 74 ++++++++++++++++++++----
 3 files changed, 96 insertions(+), 13 deletions(-)

diff --git a/spec/ameba/formatter/util_spec.cr b/spec/ameba/formatter/util_spec.cr
index e2f95423d..9a002baa7 100644
--- a/spec/ameba/formatter/util_spec.cr
+++ b/spec/ameba/formatter/util_spec.cr
@@ -22,7 +22,38 @@ module Ameba::Formatter
           a = 1
         )
         location = Crystal::Location.new("filename", 1, 1)
-        subject.affected_code(source, location).should eq "> a = 1\n  \e[33m^\e[0m"
+        subject.deansify(subject.affected_code(source, location))
+          .should eq "> a = 1\n  ^"
+      end
+
+      it "returns correct line if it is found" do
+        source = Source.new <<-EOF
+          # pre:1
+            # pre:2
+              # pre:3
+                # pre:4
+                  # pre:5
+          a = 1
+                  # post:1
+                # post:2
+              # post:3
+            # post:4
+          # post:5
+          EOF
+
+        location = Crystal::Location.new("filename", 6, 1)
+        subject.deansify(subject.affected_code(source, location, context_lines: 3))
+          .should eq <<-STR
+            >     # pre:3
+            >       # pre:4
+            >         # pre:5
+            > a = 1
+              ^
+            >         # post:1
+            >       # post:2
+            >     # post:3
+
+            STR
       end
     end
   end
diff --git a/src/ameba/formatter/explain_formatter.cr b/src/ameba/formatter/explain_formatter.cr
index 9220ae3fa..87fb15b6d 100644
--- a/src/ameba/formatter/explain_formatter.cr
+++ b/src/ameba/formatter/explain_formatter.cr
@@ -49,7 +49,7 @@ module Ameba::Formatter
         @location.to_s.colorize(:cyan).to_s,
       ]
 
-      if affected_code = affected_code(source, @location)
+      if affected_code = affected_code(source, @location, context_lines: 3)
         output_title "AFFECTED CODE"
         output_paragraph affected_code
       end
diff --git a/src/ameba/formatter/util.cr b/src/ameba/formatter/util.cr
index 26410313d..822489f06 100644
--- a/src/ameba/formatter/util.cr
+++ b/src/ameba/formatter/util.cr
@@ -1,22 +1,74 @@
 module Ameba::Formatter
   module Util
-    def affected_code(source, location, max_length = 100, placeholder = " ...", prompt = "> ")
-      line, column = location.line_number, location.column_number
-      affected_line = source.lines[line - 1]?.presence
+    def deansify(message : String?) : String?
+      message.try &.gsub(/\x1b[^m]*m/, "").presence
+    end
+
+    def affected_code(source, location, context_lines = 0, max_length = 100, placeholder = " ...", prompt = "> ")
+      lines = source.lines
+      lineno, column =
+        location.line_number, location.column_number
+
+      return unless affected_line = lines[lineno - 1]?.presence
 
-      return unless affected_line
+      trim_line = Proc(String, String).new do |line|
+        if line.size > max_length
+          line = line[0, max_length - placeholder.size - 1] + placeholder
+        end
+        line
+      end
 
-      if affected_line.size > max_length && column < max_length
-        affected_line = affected_line[0, max_length - placeholder.size - 1] + placeholder
+      if column < max_length
+        affected_line = trim_line.call(affected_line)
       end
 
-      stripped = affected_line.lstrip
-      position = column - (affected_line.size - stripped.size) + prompt.size
+      show_context = context_lines > 0
+      if show_context
+        pre_context, post_context = %w[], %w[]
+
+        lines.each_with_index do |line, i|
+          case i + 1
+          when lineno - context_lines...lineno
+            pre_context << trim_line.call(line)
+          when lineno
+            #
+          when lineno + 1..lineno + context_lines
+            post_context << trim_line.call(line)
+          end
+        end
+
+        # remove empty lines at the beginning/end
+        pre_context.shift? unless pre_context.first?.presence
+        post_context.pop? unless post_context.last?.presence
+      end
 
       String.build do |str|
-        str << prompt << stripped << '\n'
-        str << " " * (position - 1)
-        str << "^".colorize(:yellow)
+        if show_context
+          pre_context.try &.each do |line|
+            str << prompt
+            str.puts(line.colorize(:dark_gray))
+          end
+
+          str << prompt
+          str.puts(affected_line.colorize(:white))
+
+          str << " " * (prompt.size + column - 1)
+          str.puts("^".colorize(:yellow))
+
+          post_context.try &.each do |line|
+            str << prompt
+            str.puts(line.colorize(:dark_gray))
+          end
+        else
+          stripped = affected_line.lstrip
+          position = column - (affected_line.size - stripped.size) + prompt.size
+
+          str << prompt
+          str.puts(stripped)
+
+          str << " " * (position - 1)
+          str << "^".colorize(:yellow)
+        end
       end
     end
   end

From 6f0f8352f9c0189bf4c6416e77d47ca1e1c80e04 Mon Sep 17 00:00:00 2001
From: Anton Maminov <anton.linux@gmail.com>
Date: Sat, 16 Jan 2021 20:42:27 +0200
Subject: [PATCH 04/37] fix Crystal nightly

---
 src/ameba/reportable.cr | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ameba/reportable.cr b/src/ameba/reportable.cr
index 354539506..e31ef3a74 100644
--- a/src/ameba/reportable.cr
+++ b/src/ameba/reportable.cr
@@ -5,7 +5,7 @@ module Ameba
     getter issues = [] of Issue
 
     # Adds a new issue to the list of issues.
-    def add_issue(rule, location, end_location, message, status = nil)
+    def add_issue(rule, location : Crystal::Location?, end_location : Crystal::Location?, message, status = nil)
       status ||= :disabled if location_disabled?(location, rule)
       issues << Issue.new rule, location, end_location, message, status
     end

From 1a091c1f1a5b6c52ee10c047975847c5f81fd198 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 17 Jan 2021 13:16:04 +0100
Subject: [PATCH 05/37] Optimize rules (#185)

* Replace pointless interpolations with actual values

* Rules optimizations

* Stylistic refactors

* Remove extraneous blank lines

* Remove some instances of .not_nil! usage
---
 spec/ameba/rule/lint/redundant_with_object_spec.cr |  2 +-
 src/ameba/cli/cmd.cr                               |  9 +++++++--
 src/ameba/rule/layout/line_length.cr               |  5 +----
 src/ameba/rule/layout/trailing_blank_lines.cr      |  1 -
 src/ameba/rule/layout/trailing_whitespace.cr       |  4 +---
 src/ameba/rule/lint/bad_directive.cr               |  5 +++--
 src/ameba/rule/lint/comparison_to_boolean.cr       |  5 +----
 src/ameba/rule/lint/debugger_statement.cr          |  1 -
 src/ameba/rule/lint/empty_ensure.cr                |  1 -
 src/ameba/rule/lint/empty_expression.cr            |  4 +---
 src/ameba/rule/lint/hash_duplicated_key.cr         |  5 ++---
 src/ameba/rule/lint/literal_in_condition.cr        |  1 -
 src/ameba/rule/lint/literal_in_interpolation.cr    |  1 -
 src/ameba/rule/lint/percent_array.cr               |  1 -
 src/ameba/rule/lint/rand_zero.cr                   |  3 +--
 src/ameba/rule/lint/redundant_string_coercion.cr   |  1 -
 src/ameba/rule/lint/redundant_with_index.cr        |  4 ++--
 src/ameba/rule/lint/redundant_with_object.cr       |  7 +++----
 src/ameba/rule/lint/shadowed_argument.cr           |  1 -
 src/ameba/rule/lint/shadowed_exception.cr          |  1 -
 src/ameba/rule/lint/shadowing_local_outer_var.cr   |  1 -
 src/ameba/rule/lint/shared_var_in_fiber.cr         |  3 +--
 src/ameba/rule/lint/syntax.cr                      |  1 -
 src/ameba/rule/lint/unneeded_disable_directive.cr  |  4 ++--
 src/ameba/rule/lint/unreachable_code.cr            |  1 -
 src/ameba/rule/lint/unused_argument.cr             |  1 -
 src/ameba/rule/lint/useless_assign.cr              |  1 -
 src/ameba/rule/lint/useless_condition_in_when.cr   |  6 +-----
 src/ameba/rule/metrics/cyclomatic_complexity.cr    | 14 +++++++-------
 src/ameba/rule/performance/any_after_filter.cr     |  8 ++++----
 .../rule/performance/first_last_after_filter.cr    |  7 +++----
 src/ameba/rule/performance/size_after_filter.cr    |  8 ++++----
 src/ameba/rule/style/constant_names.cr             |  3 +--
 src/ameba/rule/style/is_a_nil.cr                   |  5 +++--
 src/ameba/rule/style/large_numbers.cr              |  5 ++---
 src/ameba/rule/style/method_names.cr               |  3 +--
 .../rule/style/negated_conditions_in_unless.cr     |  4 +---
 src/ameba/rule/style/predicate_name.cr             |  1 -
 src/ameba/rule/style/redundant_begin.cr            |  5 +----
 src/ameba/rule/style/type_names.cr                 |  3 +--
 src/ameba/rule/style/unless_else.cr                |  4 +---
 src/ameba/rule/style/variable_names.cr             |  1 -
 src/ameba/rule/style/while_true.cr                 |  4 +---
 43 files changed, 57 insertions(+), 98 deletions(-)

diff --git a/spec/ameba/rule/lint/redundant_with_object_spec.cr b/spec/ameba/rule/lint/redundant_with_object_spec.cr
index f6adc130e..bc3a9baf6 100644
--- a/spec/ameba/rule/lint/redundant_with_object_spec.cr
+++ b/spec/ameba/rule/lint/redundant_with_object_spec.cr
@@ -77,7 +77,7 @@ module Ameba::Rule::Lint
       issue.rule.should_not be_nil
       issue.location.to_s.should eq "source.cr:2:14"
       issue.end_location.to_s.should eq "source.cr:2:30"
-      issue.message.should eq "Use each instead of each_with_object"
+      issue.message.should eq "Use `each` instead of `each_with_object`"
     end
   end
 end
diff --git a/src/ameba/cli/cmd.cr b/src/ameba/cli/cmd.cr
index 7b9e6bae3..d32543c45 100644
--- a/src/ameba/cli/cmd.cr
+++ b/src/ameba/cli/cmd.cr
@@ -8,8 +8,13 @@ module Ameba::Cli
   def run(args = ARGV)
     opts = parse_args args
     config = Config.load opts.config, opts.colors?
-    config.globs = opts.globs.not_nil! if opts.globs
-    config.severity = opts.fail_level.not_nil! if opts.fail_level
+
+    if globs = opts.globs
+      config.globs = globs
+    end
+    if fail_level = opts.fail_level
+      config.severity = fail_level
+    end
 
     configure_formatter(config, opts)
     configure_rules(config, opts)
diff --git a/src/ameba/rule/layout/line_length.cr b/src/ameba/rule/layout/line_length.cr
index a4c24d37d..df8430701 100644
--- a/src/ameba/rule/layout/line_length.cr
+++ b/src/ameba/rule/layout/line_length.cr
@@ -8,7 +8,6 @@ module Ameba::Rule::Layout
   #   Enabled: true
   #   MaxLength: 100
   # ```
-  #
   struct LineLength < Base
     properties do
       enabled false
@@ -20,9 +19,7 @@ module Ameba::Rule::Layout
 
     def test(source)
       source.lines.each_with_index do |line, index|
-        next unless line.size > max_length
-
-        issue_for({index + 1, max_length + 1}, MSG)
+        issue_for({index + 1, max_length + 1}, MSG) if line.size > max_length
       end
     end
   end
diff --git a/src/ameba/rule/layout/trailing_blank_lines.cr b/src/ameba/rule/layout/trailing_blank_lines.cr
index 24499e9c0..bf2db9d67 100644
--- a/src/ameba/rule/layout/trailing_blank_lines.cr
+++ b/src/ameba/rule/layout/trailing_blank_lines.cr
@@ -7,7 +7,6 @@ module Ameba::Rule::Layout
   # Layout/TrailingBlankLines:
   #   Enabled: true
   # ```
-  #
   struct TrailingBlankLines < Base
     properties do
       description "Disallows trailing blank lines"
diff --git a/src/ameba/rule/layout/trailing_whitespace.cr b/src/ameba/rule/layout/trailing_whitespace.cr
index a4df797ee..77456c1a7 100644
--- a/src/ameba/rule/layout/trailing_whitespace.cr
+++ b/src/ameba/rule/layout/trailing_whitespace.cr
@@ -7,7 +7,6 @@ module Ameba::Rule::Layout
   # Layout/TrailingWhitespace:
   #   Enabled: true
   # ```
-  #
   struct TrailingWhitespace < Base
     properties do
       description "Disallows trailing whitespaces"
@@ -17,8 +16,7 @@ module Ameba::Rule::Layout
 
     def test(source)
       source.lines.each_with_index do |line, index|
-        next unless line =~ /\s$/
-        issue_for({index + 1, line.size}, MSG)
+        issue_for({index + 1, line.size}, MSG) if line =~ /\s$/
       end
     end
   end
diff --git a/src/ameba/rule/lint/bad_directive.cr b/src/ameba/rule/lint/bad_directive.cr
index 76b6d3589..1fcfd896a 100644
--- a/src/ameba/rule/lint/bad_directive.cr
+++ b/src/ameba/rule/lint/bad_directive.cr
@@ -17,7 +17,6 @@ module Ameba::Rule::Lint
   # Lint/BadDirective:
   #   Enabled: true
   # ```
-  #
   struct BadDirective < Base
     properties do
       description "Reports bad comment directives"
@@ -48,7 +47,9 @@ module Ameba::Rule::Lint
 
     private def check_rules(source, token, rules)
       bad_names = rules - ALL_RULE_NAMES - ALL_GROUP_NAMES
-      issue_for token, "Such rules do not exist: %s" % bad_names.join(", ") unless bad_names.empty?
+      return if bad_names.empty?
+
+      issue_for token, "Such rules do not exist: %s" % bad_names.join(", ")
     end
   end
 end
diff --git a/src/ameba/rule/lint/comparison_to_boolean.cr b/src/ameba/rule/lint/comparison_to_boolean.cr
index 313db5a22..649d61a56 100644
--- a/src/ameba/rule/lint/comparison_to_boolean.cr
+++ b/src/ameba/rule/lint/comparison_to_boolean.cr
@@ -19,7 +19,6 @@ module Ameba::Rule::Lint
   # Lint/ComparisonToBoolean:
   #   Enabled: true
   # ```
-  #
   struct ComparisonToBoolean < Base
     properties do
       enabled false
@@ -33,9 +32,7 @@ module Ameba::Rule::Lint
       to_boolean = node.args.first?.try &.is_a?(Crystal::BoolLiteral) ||
                    node.obj.is_a?(Crystal::BoolLiteral)
 
-      return unless comparison && to_boolean
-
-      issue_for node, MSG
+      issue_for node, MSG if comparison && to_boolean
     end
   end
 end
diff --git a/src/ameba/rule/lint/debugger_statement.cr b/src/ameba/rule/lint/debugger_statement.cr
index 976744901..b5131384c 100644
--- a/src/ameba/rule/lint/debugger_statement.cr
+++ b/src/ameba/rule/lint/debugger_statement.cr
@@ -10,7 +10,6 @@ module Ameba::Rule::Lint
   # Lint/DebuggerStatement:
   #   Enabled: true
   # ```
-  #
   struct DebuggerStatement < Base
     properties do
       description "Disallows calls to debugger"
diff --git a/src/ameba/rule/lint/empty_ensure.cr b/src/ameba/rule/lint/empty_ensure.cr
index f8fdeb48e..94deeb369 100644
--- a/src/ameba/rule/lint/empty_ensure.cr
+++ b/src/ameba/rule/lint/empty_ensure.cr
@@ -38,7 +38,6 @@ module Ameba::Rule::Lint
   # Lint/EmptyEnsure
   #   Enabled: true
   # ```
-  #
   struct EmptyEnsure < Base
     properties do
       description "Disallows empty ensure statement"
diff --git a/src/ameba/rule/lint/empty_expression.cr b/src/ameba/rule/lint/empty_expression.cr
index 682ed8a35..e3fae35ac 100644
--- a/src/ameba/rule/lint/empty_expression.cr
+++ b/src/ameba/rule/lint/empty_expression.cr
@@ -27,7 +27,6 @@ module Ameba::Rule::Lint
   # Lint/EmptyExpression:
   #   Enabled: true
   # ```
-  #
   struct EmptyExpression < Base
     include AST::Util
 
@@ -41,8 +40,7 @@ module Ameba::Rule::Lint
 
     def test(source, node : Crystal::NilLiteral)
       exp = node_source(node, source.lines).try &.join
-
-      return if exp.nil? || exp == "nil"
+      return if exp.in?(nil, "nil")
 
       issue_for node, MSG % exp
     end
diff --git a/src/ameba/rule/lint/hash_duplicated_key.cr b/src/ameba/rule/lint/hash_duplicated_key.cr
index c9de6a788..6a581b4f5 100644
--- a/src/ameba/rule/lint/hash_duplicated_key.cr
+++ b/src/ameba/rule/lint/hash_duplicated_key.cr
@@ -19,7 +19,6 @@ module Ameba::Rule::Lint
   # Lint/HashDuplicatedKey:
   #   Enabled: true
   # ```
-  #
   struct HashDuplicatedKey < Base
     properties do
       description "Disallows duplicated keys in hash literals"
@@ -28,7 +27,7 @@ module Ameba::Rule::Lint
     MSG = "Duplicated keys in hash literal: %s"
 
     def test(source, node : Crystal::HashLiteral)
-      return unless (keys = duplicated_keys(node.entries)).any?
+      return if (keys = duplicated_keys(node.entries)).empty?
 
       issue_for node, MSG % keys.join(", ")
     end
@@ -36,7 +35,7 @@ module Ameba::Rule::Lint
     private def duplicated_keys(entries)
       entries.map(&.key)
         .group_by(&.itself)
-        .select { |_, v| v.size > 1 }
+        .tap(&.select! { |_, v| v.size > 1 })
         .map { |k, _| k }
     end
   end
diff --git a/src/ameba/rule/lint/literal_in_condition.cr b/src/ameba/rule/lint/literal_in_condition.cr
index 2dc2e6004..154785169 100644
--- a/src/ameba/rule/lint/literal_in_condition.cr
+++ b/src/ameba/rule/lint/literal_in_condition.cr
@@ -19,7 +19,6 @@ module Ameba::Rule::Lint
   # Lint/LiteralInCondition:
   #   Enabled: true
   # ```
-  #
   struct LiteralInCondition < Base
     include AST::Util
 
diff --git a/src/ameba/rule/lint/literal_in_interpolation.cr b/src/ameba/rule/lint/literal_in_interpolation.cr
index df674f74f..6c96c1c87 100644
--- a/src/ameba/rule/lint/literal_in_interpolation.cr
+++ b/src/ameba/rule/lint/literal_in_interpolation.cr
@@ -15,7 +15,6 @@ module Ameba::Rule::Lint
   # Lint/LiteralInInterpolation
   #   Enabled: true
   # ```
-  #
   struct LiteralInInterpolation < Base
     include AST::Util
 
diff --git a/src/ameba/rule/lint/percent_array.cr b/src/ameba/rule/lint/percent_array.cr
index afdf02230..b8bb1b547 100644
--- a/src/ameba/rule/lint/percent_array.cr
+++ b/src/ameba/rule/lint/percent_array.cr
@@ -23,7 +23,6 @@ module Ameba::Rule::Lint
   #   StringArrayUnwantedSymbols: ',"'
   #   SymbolArrayUnwantedSymbols: ',:'
   # ```
-  #
   struct PercentArrays < Base
     properties do
       description "Disallows some unwanted symbols in percent array literals"
diff --git a/src/ameba/rule/lint/rand_zero.cr b/src/ameba/rule/lint/rand_zero.cr
index 6c2b70f28..efd8ab7b6 100644
--- a/src/ameba/rule/lint/rand_zero.cr
+++ b/src/ameba/rule/lint/rand_zero.cr
@@ -22,7 +22,6 @@ module Ameba::Rule::Lint
   # Lint/RandZero:
   #   Enabled: true
   # ```
-  #
   struct RandZero < Base
     properties do
       description "Disallows rand zero calls"
@@ -36,7 +35,7 @@ module Ameba::Rule::Lint
                     (arg = node.args.first) &&
                     (arg.is_a? Crystal::NumberLiteral) &&
                     (value = arg.value) &&
-                    (value == "0" || value == "1")
+                    value.in?("0", "1")
 
       issue_for node, MSG % node
     end
diff --git a/src/ameba/rule/lint/redundant_string_coercion.cr b/src/ameba/rule/lint/redundant_string_coercion.cr
index f21484a22..4e85de492 100644
--- a/src/ameba/rule/lint/redundant_string_coercion.cr
+++ b/src/ameba/rule/lint/redundant_string_coercion.cr
@@ -20,7 +20,6 @@ module Ameba::Rule::Lint
   # Lint/RedundantStringCoersion
   #   Enabled: true
   # ```
-  #
   struct RedundantStringCoercion < Base
     include AST::Util
 
diff --git a/src/ameba/rule/lint/redundant_with_index.cr b/src/ameba/rule/lint/redundant_with_index.cr
index d9c646f39..35d3ffc91 100644
--- a/src/ameba/rule/lint/redundant_with_index.cr
+++ b/src/ameba/rule/lint/redundant_with_index.cr
@@ -26,7 +26,6 @@ module Ameba::Rule::Lint
   # Lint/RedundantWithIndex:
   #   Enabled: true
   # ```
-  #
   struct RedundantWithIndex < Base
     properties do
       description "Disallows redundant `with_index` calls"
@@ -35,7 +34,8 @@ module Ameba::Rule::Lint
     def test(source, node : Crystal::Call)
       args, block = node.args, node.block
 
-      return if args.size > 1 || block.nil? || with_index_arg?(block.not_nil!)
+      return if block.nil? || args.size > 1
+      return if with_index_arg?(block)
 
       case node.name
       when "with_index"
diff --git a/src/ameba/rule/lint/redundant_with_object.cr b/src/ameba/rule/lint/redundant_with_object.cr
index 357e45d24..585e63849 100644
--- a/src/ameba/rule/lint/redundant_with_object.cr
+++ b/src/ameba/rule/lint/redundant_with_object.cr
@@ -27,21 +27,20 @@ module Ameba::Rule::Lint
   # Lint/RedundantWithObject:
   #   Enabled: true
   # ```
-  #
   struct RedundantWithObject < Base
     properties do
       description "Disallows redundant `with_object` calls"
     end
 
+    MSG = "Use `each` instead of `each_with_object`"
+
     def test(source, node : Crystal::Call)
       return if node.name != "each_with_object" ||
                 node.args.size != 1 ||
                 node.block.nil? ||
                 with_index_arg?(node.block.not_nil!)
 
-      issue_for node.name_location,
-        node.name_end_location,
-        "Use each instead of each_with_object"
+      issue_for node.name_location, node.name_end_location, MSG
     end
 
     private def with_index_arg?(block : Crystal::Block)
diff --git a/src/ameba/rule/lint/shadowed_argument.cr b/src/ameba/rule/lint/shadowed_argument.cr
index 0c27c25df..444c24e45 100644
--- a/src/ameba/rule/lint/shadowed_argument.cr
+++ b/src/ameba/rule/lint/shadowed_argument.cr
@@ -35,7 +35,6 @@ module Ameba::Rule::Lint
   # Lint/ShadowedArgument:
   #   Enabled: true
   # ```
-  #
   struct ShadowedArgument < Base
     properties do
       description "Disallows shadowed arguments"
diff --git a/src/ameba/rule/lint/shadowed_exception.cr b/src/ameba/rule/lint/shadowed_exception.cr
index 535703407..a937f8bb5 100644
--- a/src/ameba/rule/lint/shadowed_exception.cr
+++ b/src/ameba/rule/lint/shadowed_exception.cr
@@ -33,7 +33,6 @@ module Ameba::Rule::Lint
   # Lint/ShadowedException:
   #   Enabled: true
   # ```
-  #
   struct ShadowedException < Base
     properties do
       description "Disallows rescued exception that get shadowed"
diff --git a/src/ameba/rule/lint/shadowing_local_outer_var.cr b/src/ameba/rule/lint/shadowing_local_outer_var.cr
index 846cc4840..dbfc4da05 100644
--- a/src/ameba/rule/lint/shadowing_local_outer_var.cr
+++ b/src/ameba/rule/lint/shadowing_local_outer_var.cr
@@ -30,7 +30,6 @@ module Ameba::Rule::Lint
   # Lint/ShadowingOuterLocalVar:
   #   Enabled: true
   # ```
-  #
   struct ShadowingOuterLocalVar < Base
     properties do
       description "Disallows the usage of the same name as outer local variables" \
diff --git a/src/ameba/rule/lint/shared_var_in_fiber.cr b/src/ameba/rule/lint/shared_var_in_fiber.cr
index 8011fa036..56cc465ba 100644
--- a/src/ameba/rule/lint/shared_var_in_fiber.cr
+++ b/src/ameba/rule/lint/shared_var_in_fiber.cr
@@ -49,7 +49,6 @@ module Ameba::Rule::Lint
   # Lint/SharedVarInFiber:
   #   Enabled: true
   # ```
-  #
   struct SharedVarInFiber < Base
     properties do
       description "Disallows shared variables in fibers."
@@ -77,7 +76,7 @@ module Ameba::Rule::Lint
       declared_in = variable.assignments.first?.try &.branch
 
       variable.assignments
-        .reject { |assign| assign.scope.spawn_block? }
+        .reject(&.scope.spawn_block?)
         .any? do |assign|
           assign.branch.try(&.in_loop?) && assign.branch != declared_in
         end
diff --git a/src/ameba/rule/lint/syntax.cr b/src/ameba/rule/lint/syntax.cr
index 8d135401e..6c4efa48f 100644
--- a/src/ameba/rule/lint/syntax.cr
+++ b/src/ameba/rule/lint/syntax.cr
@@ -18,7 +18,6 @@ module Ameba::Rule::Lint
   # rescue e : Exception
   # end
   # ```
-  #
   struct Syntax < Base
     properties do
       description "Reports invalid Crystal syntax"
diff --git a/src/ameba/rule/lint/unneeded_disable_directive.cr b/src/ameba/rule/lint/unneeded_disable_directive.cr
index 6128fbeba..7016f7699 100644
--- a/src/ameba/rule/lint/unneeded_disable_directive.cr
+++ b/src/ameba/rule/lint/unneeded_disable_directive.cr
@@ -24,7 +24,6 @@ module Ameba::Rule::Lint
   # Lint/UnneededDisableDirective
   #   Enabled: true
   # ```
-  #
   struct UnneededDisableDirective < Base
     properties do
       description "Reports unneeded disable directives in comments"
@@ -47,11 +46,12 @@ module Ameba::Rule::Lint
       return unless directive[:action] == "disable"
 
       directive[:rules].reject do |rule_name|
+        next if rule_name == self.name
         source.issues.any? do |issue|
           issue.rule.name == rule_name &&
             issue.disabled? &&
             issue_at_location?(source, issue, location)
-        end && rule_name != self.name
+        end
       end
     end
 
diff --git a/src/ameba/rule/lint/unreachable_code.cr b/src/ameba/rule/lint/unreachable_code.cr
index ded09bf57..69f3731f2 100644
--- a/src/ameba/rule/lint/unreachable_code.cr
+++ b/src/ameba/rule/lint/unreachable_code.cr
@@ -41,7 +41,6 @@ module Ameba::Rule::Lint
   # Lint/UnreachableCode:
   #   Enabled: true
   # ```
-  #
   struct UnreachableCode < Base
     include AST::Util
 
diff --git a/src/ameba/rule/lint/unused_argument.cr b/src/ameba/rule/lint/unused_argument.cr
index 6abadca80..9615ec4cc 100644
--- a/src/ameba/rule/lint/unused_argument.cr
+++ b/src/ameba/rule/lint/unused_argument.cr
@@ -24,7 +24,6 @@ module Ameba::Rule::Lint
   #   IgnoreBlocks: false
   #   IgnoreProcs: false
   # ```
-  #
   struct UnusedArgument < Base
     properties do
       description "Disallows unused arguments"
diff --git a/src/ameba/rule/lint/useless_assign.cr b/src/ameba/rule/lint/useless_assign.cr
index bff181889..23f69d4f2 100644
--- a/src/ameba/rule/lint/useless_assign.cr
+++ b/src/ameba/rule/lint/useless_assign.cr
@@ -25,7 +25,6 @@ module Ameba::Rule::Lint
   # Lint/UselessAssign:
   #   Enabled: true
   # ```
-  #
   struct UselessAssign < Base
     properties do
       description "Disallows useless variable assignments"
diff --git a/src/ameba/rule/lint/useless_condition_in_when.cr b/src/ameba/rule/lint/useless_condition_in_when.cr
index 4b2fb36cf..f9f40ca65 100644
--- a/src/ameba/rule/lint/useless_condition_in_when.cr
+++ b/src/ameba/rule/lint/useless_condition_in_when.cr
@@ -30,7 +30,6 @@ module Ameba::Rule::Lint
   # Lint/UselessConditionInWhen:
   #   Enabled: true
   # ```
-  #
   struct UselessConditionInWhen < Base
     properties do
       description "Disallows useless conditions in when"
@@ -43,10 +42,7 @@ module Ameba::Rule::Lint
     # simple implementation in future.
     protected def check_node(source, when_node, cond)
       cond_s = cond.to_s
-      return if when_node
-                  .conds
-                  .map(&.to_s)
-                  .none? { |c| c == cond_s }
+      return if when_node.conds.none?(&.to_s.==(cond_s))
 
       issue_for cond, MSG
     end
diff --git a/src/ameba/rule/metrics/cyclomatic_complexity.cr b/src/ameba/rule/metrics/cyclomatic_complexity.cr
index fb2e2fe22..167ebfe77 100644
--- a/src/ameba/rule/metrics/cyclomatic_complexity.cr
+++ b/src/ameba/rule/metrics/cyclomatic_complexity.cr
@@ -8,7 +8,6 @@ module Ameba::Rule::Metrics
   #   Enabled: true
   #   MaxComplexity: 10
   # ```
-  #
   struct CyclomaticComplexity < Base
     properties do
       description "Disallows methods with a cyclomatic complexity higher than `MaxComplexity`"
@@ -21,17 +20,18 @@ module Ameba::Rule::Metrics
       complexity = AST::CountingVisitor.new(node).count
 
       if complexity > max_complexity && (location = node.name_location)
-        issue_for(
-          location,
-          def_name_end_location(node),
-          MSG % {complexity, max_complexity}
-        )
+        issue_for location, def_name_end_location(node), MSG % {
+          complexity, max_complexity,
+        }
       end
     end
 
     private def def_name_end_location(node)
       return unless location = node.name_location
-      line_number, column_number = location.line_number, location.column_number
+
+      line_number, column_number =
+        location.line_number, location.column_number
+
       Crystal::Location.new(location.filename, line_number, column_number + node.name.size)
     end
   end
diff --git a/src/ameba/rule/performance/any_after_filter.cr b/src/ameba/rule/performance/any_after_filter.cr
index 5e4ae0772..b8aa3f342 100644
--- a/src/ameba/rule/performance/any_after_filter.cr
+++ b/src/ameba/rule/performance/any_after_filter.cr
@@ -24,10 +24,9 @@ module Ameba::Rule::Performance
   #     - select
   #     - reject
   # ```
-  #
   struct AnyAfterFilter < Base
     ANY_NAME = "any?"
-    MSG      = "Use `#{ANY_NAME} {...}` instead of `%s {...}.#{ANY_NAME}`"
+    MSG      = "Use `any? {...}` instead of `%s {...}.any?`"
 
     properties do
       filter_names : Array(String) = %w(select reject)
@@ -36,9 +35,10 @@ module Ameba::Rule::Performance
 
     def test(source, node : Crystal::Call)
       return unless node.name == ANY_NAME && (obj = node.obj)
+      return unless obj.is_a?(Crystal::Call)
+      return if obj.block.nil? || !node.block.nil?
 
-      if node.block.nil? && obj.is_a?(Crystal::Call) &&
-         filter_names.includes?(obj.name) && !obj.block.nil?
+      if filter_names.includes?(obj.name)
         issue_for obj.name_location, node.name_end_location, MSG % obj.name
       end
     end
diff --git a/src/ameba/rule/performance/first_last_after_filter.cr b/src/ameba/rule/performance/first_last_after_filter.cr
index a35994230..78f3302a5 100644
--- a/src/ameba/rule/performance/first_last_after_filter.cr
+++ b/src/ameba/rule/performance/first_last_after_filter.cr
@@ -23,7 +23,6 @@ module Ameba::Rule::Performance
   #   FilterNames:
   #     - select
   # ```
-  #
   struct FirstLastAfterFilter < Base
     CALL_NAMES  = %w(first last first? last?)
     MSG         = "Use `find {...}` instead of `%s {...}.%s`"
@@ -45,10 +44,10 @@ module Ameba::Rule::Performance
 
     def test(source, node : Crystal::Call)
       return unless CALL_NAMES.includes?(node.name) && (obj = node.obj)
-      return if node.args.any?
+      return unless obj.is_a?(Crystal::Call)
+      return if obj.block.nil? || !node.block.nil? || node.args.any?
 
-      if node.block.nil? && obj.is_a?(Crystal::Call) &&
-         filter_names.includes?(obj.name) && !obj.block.nil?
+      if filter_names.includes?(obj.name)
         message = node.name.includes?(CALL_NAMES.first) ? MSG : MSG_REVERSE
         issue_for obj.name_location, node.name_end_location, message % {obj.name, node.name}
       end
diff --git a/src/ameba/rule/performance/size_after_filter.cr b/src/ameba/rule/performance/size_after_filter.cr
index 1fe26359b..6a2814326 100644
--- a/src/ameba/rule/performance/size_after_filter.cr
+++ b/src/ameba/rule/performance/size_after_filter.cr
@@ -30,10 +30,9 @@ module Ameba::Rule::Performance
   #     - select
   #     - reject
   # ```
-  #
   struct SizeAfterFilter < Base
     SIZE_NAME = "size"
-    MSG       = "Use `count {...}` instead of `%s {...}.#{SIZE_NAME}`."
+    MSG       = "Use `count {...}` instead of `%s {...}.size`."
 
     properties do
       filter_names : Array(String) = %w(select reject)
@@ -51,9 +50,10 @@ module Ameba::Rule::Performance
 
     def test(source, node : Crystal::Call)
       return unless node.name == SIZE_NAME && (obj = node.obj)
+      return unless obj.is_a?(Crystal::Call)
+      return if obj.block.nil?
 
-      if obj.is_a?(Crystal::Call) &&
-         filter_names.includes?(obj.name) && !obj.block.nil?
+      if filter_names.includes?(obj.name)
         issue_for obj.name_location, node.name_end_location, MSG % obj.name
       end
     end
diff --git a/src/ameba/rule/style/constant_names.cr b/src/ameba/rule/style/constant_names.cr
index 3628006e7..fdd7caada 100644
--- a/src/ameba/rule/style/constant_names.cr
+++ b/src/ameba/rule/style/constant_names.cr
@@ -21,7 +21,6 @@ module Ameba::Rule::Style
   # Style/ConstantNames:
   #   Enabled: true
   # ```
-  #
   struct ConstantNames < Base
     properties do
       description "Enforces constant names to be in screaming case"
@@ -34,7 +33,7 @@ module Ameba::Rule::Style
         name = target.names.first
         expected = name.upcase
 
-        return if expected == name || name.camelcase == name
+        return if name.in?(expected, name.camelcase)
 
         issue_for target, MSG % {expected, name}
       end
diff --git a/src/ameba/rule/style/is_a_nil.cr b/src/ameba/rule/style/is_a_nil.cr
index 18653bbc2..cbf4aced3 100644
--- a/src/ameba/rule/style/is_a_nil.cr
+++ b/src/ameba/rule/style/is_a_nil.cr
@@ -19,7 +19,6 @@ module Ameba::Rule::Style
   # Style/IsANil:
   #   Enabled: true
   # ```
-  #
   struct IsANil < Base
     properties do
       description "Disallows calls to `is_a?(Nil)` in favor of `nil?`"
@@ -32,7 +31,9 @@ module Ameba::Rule::Style
       return if node.nil_check?
 
       const = node.const
-      issue_for const, MSG if const.is_a?(Crystal::Path) && const.names == PATH_NIL_NAMES
+      return unless const.is_a?(Crystal::Path) && const.names == PATH_NIL_NAMES
+
+      issue_for const, MSG
     end
   end
 end
diff --git a/src/ameba/rule/style/large_numbers.cr b/src/ameba/rule/style/large_numbers.cr
index a9a2b33db..caba735f9 100644
--- a/src/ameba/rule/style/large_numbers.cr
+++ b/src/ameba/rule/style/large_numbers.cr
@@ -26,7 +26,6 @@ module Ameba::Rule::Style
   #   Enabled: true
   #   IntMinDigits: 5 # i.e. integers higher than 9999
   # ```
-  #
   struct LargeNumbers < Base
     properties do
       description "Disallows usage of large numbers without underscore"
@@ -53,7 +52,7 @@ module Ameba::Rule::Style
     end
 
     private def allowed?(_sign, value, fraction, _suffix)
-      return true if !fraction.nil? && fraction.size > 3
+      return true if fraction && fraction.size > 3
 
       digits = value.chars.select &.to_s.=~ /[0-9]/
       digits.size >= int_min_digits
@@ -71,7 +70,7 @@ module Ameba::Rule::Style
         value.chars.reject(&.== '_').each_slice(by) do |slice|
           slices << (yield slice).join
         end
-      end.join("_")
+      end.join('_')
     end
 
     private def parse_number(value)
diff --git a/src/ameba/rule/style/method_names.cr b/src/ameba/rule/style/method_names.cr
index 905de3735..c53a0f9af 100644
--- a/src/ameba/rule/style/method_names.cr
+++ b/src/ameba/rule/style/method_names.cr
@@ -37,7 +37,6 @@ module Ameba::Rule::Style
   # Style/MethodNames:
   #   Enabled: true
   # ```
-  #
   struct MethodNames < Base
     properties do
       description "Enforces method names to be in underscored case"
@@ -51,7 +50,7 @@ module Ameba::Rule::Style
       line_number = node.location.try &.line_number
       column_number = node.name_location.try &.column_number
 
-      return if line_number.nil? || column_number.nil?
+      return unless line_number && column_number
 
       issue_for(
         {line_number, column_number},
diff --git a/src/ameba/rule/style/negated_conditions_in_unless.cr b/src/ameba/rule/style/negated_conditions_in_unless.cr
index 8781b36a9..7225c5df6 100644
--- a/src/ameba/rule/style/negated_conditions_in_unless.cr
+++ b/src/ameba/rule/style/negated_conditions_in_unless.cr
@@ -26,7 +26,6 @@ module Ameba::Rule::Style
   # Style/NegatedConditionsInUnless:
   #   Enabled: true
   # ```
-  #
   struct NegatedConditionsInUnless < Base
     properties do
       description "Disallows negated conditions in unless"
@@ -35,8 +34,7 @@ module Ameba::Rule::Style
     MSG = "Avoid negated conditions in unless blocks"
 
     def test(source, node : Crystal::Unless)
-      return unless negated_condition? node.cond
-      issue_for node, MSG
+      issue_for node, MSG if negated_condition?(node.cond)
     end
 
     private def negated_condition?(node)
diff --git a/src/ameba/rule/style/predicate_name.cr b/src/ameba/rule/style/predicate_name.cr
index b23d938c3..a7db3ef65 100644
--- a/src/ameba/rule/style/predicate_name.cr
+++ b/src/ameba/rule/style/predicate_name.cr
@@ -28,7 +28,6 @@ module Ameba::Rule::Style
   # Style/PredicateName:
   #   Enabled: true
   # ```
-  #
   struct PredicateName < Base
     properties do
       description "Disallows tautological predicate names"
diff --git a/src/ameba/rule/style/redundant_begin.cr b/src/ameba/rule/style/redundant_begin.cr
index 1318bb4b2..db6902d8e 100644
--- a/src/ameba/rule/style/redundant_begin.cr
+++ b/src/ameba/rule/style/redundant_begin.cr
@@ -55,7 +55,6 @@ module Ameba::Rule::Style
   # Style/RedundantBegin:
   #   Enabled: true
   # ```
-  #
   struct RedundantBegin < Base
     include AST::Util
     properties do
@@ -65,9 +64,7 @@ module Ameba::Rule::Style
     MSG = "Redundant `begin` block detected"
 
     def test(source, node : Crystal::Def)
-      return unless redundant_begin?(source, node)
-
-      issue_for node, MSG
+      issue_for node, MSG if redundant_begin?(source, node)
     end
 
     private def redundant_begin?(source, node)
diff --git a/src/ameba/rule/style/type_names.cr b/src/ameba/rule/style/type_names.cr
index 2daa28f84..8cc8bb0d3 100644
--- a/src/ameba/rule/style/type_names.cr
+++ b/src/ameba/rule/style/type_names.cr
@@ -51,7 +51,6 @@ module Ameba::Rule::Style
   # Style/TypeNames:
   #   Enabled: true
   # ```
-  #
   struct TypeNames < Base
     properties do
       description "Enforces type names in camelcase manner"
@@ -62,7 +61,7 @@ module Ameba::Rule::Style
     private def check_node(source, node)
       name = node.name.to_s
       expected = name.camelcase
-      return if expected == name
+      return if name == expected
 
       issue_for node, MSG % {expected, name}
     end
diff --git a/src/ameba/rule/style/unless_else.cr b/src/ameba/rule/style/unless_else.cr
index 55909cdc7..3583c79c3 100644
--- a/src/ameba/rule/style/unless_else.cr
+++ b/src/ameba/rule/style/unless_else.cr
@@ -42,7 +42,6 @@ module Ameba::Rule::Style
   # Style/UnlessElse:
   #   Enabled: true
   # ```
-  #
   struct UnlessElse < Base
     properties do
       description "Disallows the use of an `else` block with the `unless`"
@@ -51,8 +50,7 @@ module Ameba::Rule::Style
     MSG = "Favour if over unless with else"
 
     def test(source, node : Crystal::Unless)
-      return if node.else.nop?
-      issue_for node, MSG
+      issue_for node, MSG unless node.else.nop?
     end
   end
 end
diff --git a/src/ameba/rule/style/variable_names.cr b/src/ameba/rule/style/variable_names.cr
index 108c54d0c..3d0efa34f 100644
--- a/src/ameba/rule/style/variable_names.cr
+++ b/src/ameba/rule/style/variable_names.cr
@@ -22,7 +22,6 @@ module Ameba::Rule::Style
   # Style/VariableNames:
   #   Enabled: true
   # ```
-  #
   struct VariableNames < Base
     properties do
       description "Enforces variable names to be in underscored case"
diff --git a/src/ameba/rule/style/while_true.cr b/src/ameba/rule/style/while_true.cr
index f57289e0a..06e9f1481 100644
--- a/src/ameba/rule/style/while_true.cr
+++ b/src/ameba/rule/style/while_true.cr
@@ -25,7 +25,6 @@ module Ameba::Rule::Style
   # Style/WhileTrue:
   #   Enabled: true
   # ```
-  #
   struct WhileTrue < Base
     properties do
       description "Disallows while statements with a true literal as condition"
@@ -34,8 +33,7 @@ module Ameba::Rule::Style
     MSG = "While statement using true literal as condition"
 
     def test(source, node : Crystal::While)
-      return unless node.cond.true_literal?
-      issue_for node, MSG
+      issue_for node, MSG if node.cond.true_literal?
     end
   end
 end

From 06852c490b7707abafbf28b56e7efe38543e8bb0 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 17 Jan 2021 13:25:50 +0100
Subject: [PATCH 06/37] Followup to #185

---
 src/ameba/ast/variabling/assignment.cr                |  2 +-
 src/ameba/ast/variabling/variable.cr                  |  4 ++--
 src/ameba/config.cr                                   |  2 +-
 src/ameba/formatter/todo_formatter.cr                 |  2 +-
 src/ameba/rule/lint/literal_in_condition.cr           |  3 +--
 src/ameba/rule/lint/percent_array.cr                  |  7 +++----
 src/ameba/rule/lint/rand_zero.cr                      |  2 +-
 src/ameba/rule/lint/redundant_string_coercion.cr      |  4 +++-
 src/ameba/rule/lint/shadowed_exception.cr             |  7 +++----
 src/ameba/rule/metrics/cyclomatic_complexity.cr       |  5 ++---
 src/ameba/rule/performance/any_after_filter.cr        |  8 +++-----
 src/ameba/rule/performance/first_last_after_filter.cr | 11 +++++------
 src/ameba/rule/performance/size_after_filter.cr       |  8 +++-----
 src/ameba/rule/style/constant_names.cr                |  2 +-
 src/ameba/rule/style/is_a_nil.cr                      |  5 +++--
 src/ameba/rule/style/negated_conditions_in_unless.cr  |  2 +-
 16 files changed, 34 insertions(+), 40 deletions(-)

diff --git a/src/ameba/ast/variabling/assignment.cr b/src/ameba/ast/variabling/assignment.cr
index 6908572a2..626e847f3 100644
--- a/src/ameba/ast/variabling/assignment.cr
+++ b/src/ameba/ast/variabling/assignment.cr
@@ -49,7 +49,7 @@ module Ameba::AST
     # a ||= 1
     # ```
     def op_assign?
-      node.is_a? Crystal::OpAssign
+      node.is_a?(Crystal::OpAssign)
     end
 
     # Returns true if this assignment is in a branch, false if not.
diff --git a/src/ameba/ast/variabling/variable.cr b/src/ameba/ast/variabling/variable.cr
index 1a7eab42a..526b417f1 100644
--- a/src/ameba/ast/variabling/variable.cr
+++ b/src/ameba/ast/variabling/variable.cr
@@ -91,8 +91,8 @@ module Ameba::AST
         next if consumed_branches.includes?(assignment.branch)
         assignment.referenced = true
 
-        break unless assignment.branch
-        consumed_branches << assignment.branch.not_nil!
+        break unless branch = assignment.branch
+        consumed_branches << branch
       end
     end
 
diff --git a/src/ameba/config.cr b/src/ameba/config.cr
index 5bf0261ee..c3f7b3390 100644
--- a/src/ameba/config.cr
+++ b/src/ameba/config.cr
@@ -270,7 +270,7 @@ class Ameba::Config
         include YAML::Serializable::Strict
 
         def self.new(config = nil)
-          if (raw = config.try &.raw).is_a? Hash
+          if (raw = config.try &.raw).is_a?(Hash)
             yaml = raw[rule_name]?.try &.to_yaml
           end
           from_yaml yaml || "{}"
diff --git a/src/ameba/formatter/todo_formatter.cr b/src/ameba/formatter/todo_formatter.cr
index 88584d1d6..473144074 100644
--- a/src/ameba/formatter/todo_formatter.cr
+++ b/src/ameba/formatter/todo_formatter.cr
@@ -41,7 +41,7 @@ module Ameba::Formatter
     private def rule_issues_map(issues)
       Hash(Rule::Base, Array(Issue)).new.tap do |h|
         issues.each do |issue|
-          next if issue.disabled? || issue.rule.is_a? Rule::Lint::Syntax
+          next if issue.disabled? || issue.rule.is_a?(Rule::Lint::Syntax)
           (h[issue.rule] ||= Array(Issue).new) << issue
         end
       end
diff --git a/src/ameba/rule/lint/literal_in_condition.cr b/src/ameba/rule/lint/literal_in_condition.cr
index 154785169..642350d6f 100644
--- a/src/ameba/rule/lint/literal_in_condition.cr
+++ b/src/ameba/rule/lint/literal_in_condition.cr
@@ -30,8 +30,7 @@ module Ameba::Rule::Lint
     MSG = "Literal value found in conditional"
 
     def check_node(source, node)
-      return unless literal?(node.cond)
-      issue_for node, MSG
+      issue_for node, MSG if literal?(node.cond)
     end
 
     def test(source, node : Crystal::If)
diff --git a/src/ameba/rule/lint/percent_array.cr b/src/ameba/rule/lint/percent_array.cr
index b8bb1b547..c8ea02a30 100644
--- a/src/ameba/rule/lint/percent_array.cr
+++ b/src/ameba/rule/lint/percent_array.cr
@@ -26,8 +26,8 @@ module Ameba::Rule::Lint
   struct PercentArrays < Base
     properties do
       description "Disallows some unwanted symbols in percent array literals"
-      string_array_unwanted_symbols ",\""
-      symbol_array_unwanted_symbols ",:"
+      string_array_unwanted_symbols %(,")
+      symbol_array_unwanted_symbols %(,:)
     end
 
     MSG = "Symbols `%s` may be unwanted in %s array literals"
@@ -62,8 +62,7 @@ module Ameba::Rule::Lint
     end
 
     private def check_array_entry(entry, symbols, literal)
-      return unless entry =~ /[#{symbols}]/
-      MSG % {symbols, literal}
+      MSG % {symbols, literal} if entry =~ /[#{symbols}]/
     end
   end
 end
diff --git a/src/ameba/rule/lint/rand_zero.cr b/src/ameba/rule/lint/rand_zero.cr
index efd8ab7b6..ad1843caf 100644
--- a/src/ameba/rule/lint/rand_zero.cr
+++ b/src/ameba/rule/lint/rand_zero.cr
@@ -33,7 +33,7 @@ module Ameba::Rule::Lint
       return unless node.name == "rand" &&
                     node.args.size == 1 &&
                     (arg = node.args.first) &&
-                    (arg.is_a? Crystal::NumberLiteral) &&
+                    arg.is_a?(Crystal::NumberLiteral) &&
                     (value = arg.value) &&
                     value.in?("0", "1")
 
diff --git a/src/ameba/rule/lint/redundant_string_coercion.cr b/src/ameba/rule/lint/redundant_string_coercion.cr
index 4e85de492..f451e9eac 100644
--- a/src/ameba/rule/lint/redundant_string_coercion.cr
+++ b/src/ameba/rule/lint/redundant_string_coercion.cr
@@ -30,7 +30,9 @@ module Ameba::Rule::Lint
     MSG = "Redundant use of `Object#to_s` in interpolation"
 
     def test(source, node : Crystal::StringInterpolation)
-      string_coercion_nodes(node).each { |n| issue_for n.name_location, n.end_location, MSG }
+      string_coercion_nodes(node).each do |n|
+        issue_for n.name_location, n.end_location, MSG
+      end
     end
 
     private def string_coercion_nodes(node)
diff --git a/src/ameba/rule/lint/shadowed_exception.cr b/src/ameba/rule/lint/shadowed_exception.cr
index a937f8bb5..84f2f4356 100644
--- a/src/ameba/rule/lint/shadowed_exception.cr
+++ b/src/ameba/rule/lint/shadowed_exception.cr
@@ -41,11 +41,10 @@ module Ameba::Rule::Lint
     MSG = "Exception handler has shadowed exceptions: %s"
 
     def test(source, node : Crystal::ExceptionHandler)
-      return unless excs = node.rescues
+      return unless excs = node.rescues.try &.map(&.types)
+      return if (excs = shadowed excs).empty?
 
-      if (excs = shadowed excs.map(&.types)).any?
-        issue_for node, MSG % excs.join(", ")
-      end
+      issue_for node, MSG % excs.join(", ")
     end
 
     private def shadowed(exceptions, exception_found = false)
diff --git a/src/ameba/rule/metrics/cyclomatic_complexity.cr b/src/ameba/rule/metrics/cyclomatic_complexity.cr
index 167ebfe77..9ce2bce4f 100644
--- a/src/ameba/rule/metrics/cyclomatic_complexity.cr
+++ b/src/ameba/rule/metrics/cyclomatic_complexity.cr
@@ -20,9 +20,8 @@ module Ameba::Rule::Metrics
       complexity = AST::CountingVisitor.new(node).count
 
       if complexity > max_complexity && (location = node.name_location)
-        issue_for location, def_name_end_location(node), MSG % {
-          complexity, max_complexity,
-        }
+        issue_for location, def_name_end_location(node),
+          MSG % {complexity, max_complexity}
       end
     end
 
diff --git a/src/ameba/rule/performance/any_after_filter.cr b/src/ameba/rule/performance/any_after_filter.cr
index b8aa3f342..c6dbc2b72 100644
--- a/src/ameba/rule/performance/any_after_filter.cr
+++ b/src/ameba/rule/performance/any_after_filter.cr
@@ -35,12 +35,10 @@ module Ameba::Rule::Performance
 
     def test(source, node : Crystal::Call)
       return unless node.name == ANY_NAME && (obj = node.obj)
-      return unless obj.is_a?(Crystal::Call)
-      return if obj.block.nil? || !node.block.nil?
+      return unless obj.is_a?(Crystal::Call) && obj.block && node.block.nil?
+      return unless filter_names.includes?(obj.name)
 
-      if filter_names.includes?(obj.name)
-        issue_for obj.name_location, node.name_end_location, MSG % obj.name
-      end
+      issue_for obj.name_location, node.name_end_location, MSG % obj.name
     end
   end
 end
diff --git a/src/ameba/rule/performance/first_last_after_filter.cr b/src/ameba/rule/performance/first_last_after_filter.cr
index 78f3302a5..ced0a1e3a 100644
--- a/src/ameba/rule/performance/first_last_after_filter.cr
+++ b/src/ameba/rule/performance/first_last_after_filter.cr
@@ -44,13 +44,12 @@ module Ameba::Rule::Performance
 
     def test(source, node : Crystal::Call)
       return unless CALL_NAMES.includes?(node.name) && (obj = node.obj)
-      return unless obj.is_a?(Crystal::Call)
-      return if obj.block.nil? || !node.block.nil? || node.args.any?
+      return unless obj.is_a?(Crystal::Call) && obj.block
+      return if !node.block.nil? || node.args.any?
+      return unless filter_names.includes?(obj.name)
 
-      if filter_names.includes?(obj.name)
-        message = node.name.includes?(CALL_NAMES.first) ? MSG : MSG_REVERSE
-        issue_for obj.name_location, node.name_end_location, message % {obj.name, node.name}
-      end
+      message = node.name.includes?(CALL_NAMES.first) ? MSG : MSG_REVERSE
+      issue_for obj.name_location, node.name_end_location, message % {obj.name, node.name}
     end
   end
 end
diff --git a/src/ameba/rule/performance/size_after_filter.cr b/src/ameba/rule/performance/size_after_filter.cr
index 6a2814326..0339f9989 100644
--- a/src/ameba/rule/performance/size_after_filter.cr
+++ b/src/ameba/rule/performance/size_after_filter.cr
@@ -50,12 +50,10 @@ module Ameba::Rule::Performance
 
     def test(source, node : Crystal::Call)
       return unless node.name == SIZE_NAME && (obj = node.obj)
-      return unless obj.is_a?(Crystal::Call)
-      return if obj.block.nil?
+      return unless obj.is_a?(Crystal::Call) && obj.block
+      return unless filter_names.includes?(obj.name)
 
-      if filter_names.includes?(obj.name)
-        issue_for obj.name_location, node.name_end_location, MSG % obj.name
-      end
+      issue_for obj.name_location, node.name_end_location, MSG % obj.name
     end
   end
 end
diff --git a/src/ameba/rule/style/constant_names.cr b/src/ameba/rule/style/constant_names.cr
index fdd7caada..180ed8be1 100644
--- a/src/ameba/rule/style/constant_names.cr
+++ b/src/ameba/rule/style/constant_names.cr
@@ -29,7 +29,7 @@ module Ameba::Rule::Style
     MSG = "Constant name should be screaming-cased: %s, not %s"
 
     def test(source, node : Crystal::Assign)
-      if (target = node.target).is_a? Crystal::Path
+      if (target = node.target).is_a?(Crystal::Path)
         name = target.names.first
         expected = name.upcase
 
diff --git a/src/ameba/rule/style/is_a_nil.cr b/src/ameba/rule/style/is_a_nil.cr
index cbf4aced3..4848cd2f9 100644
--- a/src/ameba/rule/style/is_a_nil.cr
+++ b/src/ameba/rule/style/is_a_nil.cr
@@ -4,7 +4,7 @@ module Ameba::Rule::Style
   # This is considered bad:
   #
   # ```
-  # var.is_a? Nil
+  # var.is_a?(Nil)
   # ```
   #
   # And needs to be written as:
@@ -31,7 +31,8 @@ module Ameba::Rule::Style
       return if node.nil_check?
 
       const = node.const
-      return unless const.is_a?(Crystal::Path) && const.names == PATH_NIL_NAMES
+      return unless const.is_a?(Crystal::Path)
+      return unless const.names == PATH_NIL_NAMES
 
       issue_for const, MSG
     end
diff --git a/src/ameba/rule/style/negated_conditions_in_unless.cr b/src/ameba/rule/style/negated_conditions_in_unless.cr
index 7225c5df6..2780e228c 100644
--- a/src/ameba/rule/style/negated_conditions_in_unless.cr
+++ b/src/ameba/rule/style/negated_conditions_in_unless.cr
@@ -42,7 +42,7 @@ module Ameba::Rule::Style
       when Crystal::BinaryOp
         negated_condition?(node.left) || negated_condition?(node.right)
       when Crystal::Expressions
-        node.expressions.any? { |e| negated_condition? e }
+        node.expressions.any? { |e| negated_condition?(e) }
       when Crystal::Not
         true
       else

From a892cd43b076a9d1332c4c3262867621fa616d53 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 17 Jan 2021 16:29:11 +0100
Subject: [PATCH 07/37] Add Performance/JoinAfterMap rule

---
 .../rule/performance/join_after_map_spec.cr   | 58 +++++++++++++++++++
 src/ameba/rule/performance/join_after_map.cr  | 48 +++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100644 spec/ameba/rule/performance/join_after_map_spec.cr
 create mode 100644 src/ameba/rule/performance/join_after_map.cr

diff --git a/spec/ameba/rule/performance/join_after_map_spec.cr b/spec/ameba/rule/performance/join_after_map_spec.cr
new file mode 100644
index 000000000..46f5d2501
--- /dev/null
+++ b/spec/ameba/rule/performance/join_after_map_spec.cr
@@ -0,0 +1,58 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Performance
+  subject = JoinAfterMap.new
+
+  describe JoinAfterMap do
+    it "passes if there is no potential performance improvements" do
+      source = Source.new %(
+        (1..3).join(&.to_s)
+        (1..3).join('.', &.to_s)
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there is map followed by join without a block" do
+      source = Source.new %(
+        (1..3).map(&.to_s).join
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    it "reports if there is map followed by join without a block (with argument)" do
+      source = Source.new %(
+        (1..3).map(&.to_s).join('.')
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    it "reports if there is map followed by join with a block" do
+      source = Source.new %(
+        (1..3).map(&.to_s).join(&.itself)
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    context "macro" do
+      it "doesn't report in macro scope" do
+        source = Source.new %(
+          {{ [1, 2, 3].map(&.to_s).join }}
+        )
+        subject.catch(source).should be_valid
+      end
+    end
+
+    it "reports rule, pos and message" do
+      s = Source.new %(
+        (1..3).map(&.to_s).join
+      ), "source.cr"
+      subject.catch(s).should_not be_valid
+      issue = s.issues.first
+
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:1:8"
+      issue.end_location.to_s.should eq "source.cr:1:24"
+      issue.message.should eq "Use `join(separator) {...}` instead of `map {...}.join(separator)`"
+    end
+  end
+end
diff --git a/src/ameba/rule/performance/join_after_map.cr b/src/ameba/rule/performance/join_after_map.cr
new file mode 100644
index 000000000..5b374b670
--- /dev/null
+++ b/src/ameba/rule/performance/join_after_map.cr
@@ -0,0 +1,48 @@
+module Ameba::Rule::Performance
+  # This rule is used to identify usage of `join` calls that follow `map`.
+  #
+  # For example, this is considered inefficient:
+  #
+  # ```
+  # (1..3).map(&.to_s).join('.')
+  # ```
+  #
+  # And can be written as this:
+  #
+  # ```
+  # (1..3).join('.', &.to_s)
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Performance/JoinAfterMap
+  #   Enabled: true
+  # ```
+  struct JoinAfterMap < Base
+    MAP_NAME  = "map"
+    JOIN_NAME = "join"
+    MSG       = "Use `join(separator) {...}` instead of `map {...}.join(separator)`"
+
+    properties do
+      description "Identifies usage of `join` calls that follow `map`."
+    end
+
+    def test(source)
+      AST::NodeVisitor.new self, source, skip: [
+        Crystal::Macro,
+        Crystal::MacroExpression,
+        Crystal::MacroIf,
+        Crystal::MacroFor,
+      ]
+    end
+
+    def test(source, node : Crystal::Call)
+      return unless node.name == JOIN_NAME && (obj = node.obj)
+      return unless obj.is_a?(Crystal::Call) && obj.block
+      return unless obj.name == MAP_NAME
+
+      issue_for obj.name_location, node.name_end_location, MSG
+    end
+  end
+end

From 5e58a60ade0bb708f3086f405309b728c3f9deda Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 17 Jan 2021 17:39:32 +0100
Subject: [PATCH 08/37] Move constant definitions after `properties` call

---
 src/ameba/rule/performance/any_after_filter.cr        | 6 +++---
 src/ameba/rule/performance/first_last_after_filter.cr | 8 ++++----
 src/ameba/rule/performance/join_after_map.cr          | 8 ++++----
 src/ameba/rule/performance/size_after_filter.cr       | 6 +++---
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/ameba/rule/performance/any_after_filter.cr b/src/ameba/rule/performance/any_after_filter.cr
index c6dbc2b72..da9662eef 100644
--- a/src/ameba/rule/performance/any_after_filter.cr
+++ b/src/ameba/rule/performance/any_after_filter.cr
@@ -25,14 +25,14 @@ module Ameba::Rule::Performance
   #     - reject
   # ```
   struct AnyAfterFilter < Base
-    ANY_NAME = "any?"
-    MSG      = "Use `any? {...}` instead of `%s {...}.any?`"
-
     properties do
       filter_names : Array(String) = %w(select reject)
       description "Identifies usage of `any?` calls that follow filters."
     end
 
+    ANY_NAME = "any?"
+    MSG      = "Use `any? {...}` instead of `%s {...}.any?`"
+
     def test(source, node : Crystal::Call)
       return unless node.name == ANY_NAME && (obj = node.obj)
       return unless obj.is_a?(Crystal::Call) && obj.block && node.block.nil?
diff --git a/src/ameba/rule/performance/first_last_after_filter.cr b/src/ameba/rule/performance/first_last_after_filter.cr
index ced0a1e3a..4b251ad8b 100644
--- a/src/ameba/rule/performance/first_last_after_filter.cr
+++ b/src/ameba/rule/performance/first_last_after_filter.cr
@@ -24,15 +24,15 @@ module Ameba::Rule::Performance
   #     - select
   # ```
   struct FirstLastAfterFilter < Base
-    CALL_NAMES  = %w(first last first? last?)
-    MSG         = "Use `find {...}` instead of `%s {...}.%s`"
-    MSG_REVERSE = "Use `reverse_each.find {...}` instead of `%s {...}.%s`"
-
     properties do
       filter_names : Array(String) = %w(select)
       description "Identifies usage of `first/last/first?/last?` calls that follow filters."
     end
 
+    CALL_NAMES  = %w(first last first? last?)
+    MSG         = "Use `find {...}` instead of `%s {...}.%s`"
+    MSG_REVERSE = "Use `reverse_each.find {...}` instead of `%s {...}.%s`"
+
     def test(source)
       AST::NodeVisitor.new self, source, skip: [
         Crystal::Macro,
diff --git a/src/ameba/rule/performance/join_after_map.cr b/src/ameba/rule/performance/join_after_map.cr
index 5b374b670..3cd742631 100644
--- a/src/ameba/rule/performance/join_after_map.cr
+++ b/src/ameba/rule/performance/join_after_map.cr
@@ -20,14 +20,14 @@ module Ameba::Rule::Performance
   #   Enabled: true
   # ```
   struct JoinAfterMap < Base
-    MAP_NAME  = "map"
-    JOIN_NAME = "join"
-    MSG       = "Use `join(separator) {...}` instead of `map {...}.join(separator)`"
-
     properties do
       description "Identifies usage of `join` calls that follow `map`."
     end
 
+    MAP_NAME  = "map"
+    JOIN_NAME = "join"
+    MSG       = "Use `join(separator) {...}` instead of `map {...}.join(separator)`"
+
     def test(source)
       AST::NodeVisitor.new self, source, skip: [
         Crystal::Macro,
diff --git a/src/ameba/rule/performance/size_after_filter.cr b/src/ameba/rule/performance/size_after_filter.cr
index 0339f9989..e825a8f78 100644
--- a/src/ameba/rule/performance/size_after_filter.cr
+++ b/src/ameba/rule/performance/size_after_filter.cr
@@ -31,14 +31,14 @@ module Ameba::Rule::Performance
   #     - reject
   # ```
   struct SizeAfterFilter < Base
-    SIZE_NAME = "size"
-    MSG       = "Use `count {...}` instead of `%s {...}.size`."
-
     properties do
       filter_names : Array(String) = %w(select reject)
       description "Identifies usage of `size` calls that follow filter"
     end
 
+    SIZE_NAME = "size"
+    MSG       = "Use `count {...}` instead of `%s {...}.size`."
+
     def test(source)
       AST::NodeVisitor.new self, source, skip: [
         Crystal::Macro,

From fd4b2f309cc01b628d20513b2c28ad72029291a8 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 17 Jan 2021 17:49:45 +0100
Subject: [PATCH 09/37] =?UTF-8?q?Don=E2=80=99t=20allocate=20the=20array=20?=
 =?UTF-8?q?on=20every=20call?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/ameba/rule/lint/comparison_to_boolean.cr | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/ameba/rule/lint/comparison_to_boolean.cr b/src/ameba/rule/lint/comparison_to_boolean.cr
index 649d61a56..474cbc86f 100644
--- a/src/ameba/rule/lint/comparison_to_boolean.cr
+++ b/src/ameba/rule/lint/comparison_to_boolean.cr
@@ -25,10 +25,11 @@ module Ameba::Rule::Lint
       description "Disallows comparison to booleans"
     end
 
-    MSG = "Comparison to a boolean is pointless"
+    MSG      = "Comparison to a boolean is pointless"
+    OP_NAMES = %w(== != ===)
 
     def test(source, node : Crystal::Call)
-      comparison = %w(== != ===).includes?(node.name)
+      comparison = node.name.in?(OP_NAMES)
       to_boolean = node.args.first?.try &.is_a?(Crystal::BoolLiteral) ||
                    node.obj.is_a?(Crystal::BoolLiteral)
 

From af5d825015e9256c674734550ff766e7f348b8e7 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 17 Jan 2021 18:12:10 +0100
Subject: [PATCH 10/37] Followup to #185

---
 src/ameba/ast/variabling/variable.cr                        | 4 ++--
 src/ameba/ast/visitors/flow_expression_visitor.cr           | 1 -
 src/ameba/ast/visitors/node_visitor.cr                      | 4 ++--
 .../ast/visitors/redundant_control_expression_visitor.cr    | 2 --
 src/ameba/ast/visitors/scope_visitor.cr                     | 2 --
 src/ameba/formatter/dot_formatter.cr                        | 4 ++--
 src/ameba/inline_comments.cr                                | 2 +-
 src/ameba/rule/base.cr                                      | 4 ++--
 src/ameba/rule/layout/trailing_blank_lines.cr               | 6 +++---
 src/ameba/rule/lint/comparison_to_boolean.cr                | 2 +-
 src/ameba/rule/lint/empty_expression.cr                     | 2 +-
 src/ameba/rule/lint/percent_array.cr                        | 1 +
 src/ameba/rule/lint/shadowed_exception.cr                   | 2 +-
 src/ameba/rule/performance/any_after_filter.cr              | 4 ++--
 src/ameba/rule/performance/first_last_after_filter.cr       | 6 +++---
 src/ameba/rule/performance/size_after_filter.cr             | 4 ++--
 src/ameba/rule/style/large_numbers.cr                       | 6 +++---
 src/ameba/rule/style/predicate_name.cr                      | 2 +-
 src/ameba/rule/style/redundant_begin.cr                     | 3 +++
 src/ameba/rule/style/redundant_next.cr                      | 1 +
 src/ameba/rule/style/redundant_return.cr                    | 1 +
 21 files changed, 32 insertions(+), 31 deletions(-)

diff --git a/src/ameba/ast/variabling/variable.cr b/src/ameba/ast/variabling/variable.cr
index 526b417f1..aa9257ac6 100644
--- a/src/ameba/ast/variabling/variable.cr
+++ b/src/ameba/ast/variabling/variable.cr
@@ -175,7 +175,7 @@ module Ameba::AST
       end
 
       def references?(node : Crystal::Var)
-        @macro_literals.any? { |literal| literal.value.includes? node.name }
+        @macro_literals.any?(&.value.includes?(node.name))
       end
 
       def visit(node : Crystal::ASTNode)
@@ -190,7 +190,7 @@ module Ameba::AST
     private def update_assign_reference!
       if @assign_before_reference.nil? &&
          references.size <= assignments.size &&
-         assignments.none? { |ass| ass.op_assign? }
+         assignments.none?(&.op_assign?)
         @assign_before_reference = assignments.find { |ass| !ass.in_branch? }.try &.node
       end
     end
diff --git a/src/ameba/ast/visitors/flow_expression_visitor.cr b/src/ameba/ast/visitors/flow_expression_visitor.cr
index f75e0d647..745927050 100644
--- a/src/ameba/ast/visitors/flow_expression_visitor.cr
+++ b/src/ameba/ast/visitors/flow_expression_visitor.cr
@@ -18,7 +18,6 @@ module Ameba::AST
       if flow_expression?(node, in_loop?)
         @rule.test @source, node, FlowExpression.new(node, in_loop?)
       end
-
       true
     end
 
diff --git a/src/ameba/ast/visitors/node_visitor.cr b/src/ameba/ast/visitors/node_visitor.cr
index 47bb343da..100c2bb49 100644
--- a/src/ameba/ast/visitors/node_visitor.cr
+++ b/src/ameba/ast/visitors/node_visitor.cr
@@ -40,7 +40,7 @@ module Ameba::AST
     @skip : Array(Crystal::ASTNode.class)?
 
     def initialize(@rule, @source, skip = nil)
-      @skip = skip.try &.map { |el| el.as(Crystal::ASTNode.class) }
+      @skip = skip.try &.map(&.as(Crystal::ASTNode.class))
       super @rule, @source
     end
 
@@ -54,7 +54,7 @@ module Ameba::AST
     {% end %}
 
     def visit(node)
-      return true unless (skip = @skip)
+      return true unless skip = @skip
       !skip.includes?(node.class)
     end
   end
diff --git a/src/ameba/ast/visitors/redundant_control_expression_visitor.cr b/src/ameba/ast/visitors/redundant_control_expression_visitor.cr
index a1ef1c3df..100f7f21d 100644
--- a/src/ameba/ast/visitors/redundant_control_expression_visitor.cr
+++ b/src/ameba/ast/visitors/redundant_control_expression_visitor.cr
@@ -28,8 +28,6 @@ module Ameba::AST
       when Crystal::Case                then traverse_case node
       when Crystal::BinaryOp            then traverse_binary_op node
       when Crystal::ExceptionHandler    then traverse_exception_handler node
-      else
-        # ok
       end
     end
 
diff --git a/src/ameba/ast/visitors/scope_visitor.cr b/src/ameba/ast/visitors/scope_visitor.cr
index 084e83aea..619278800 100644
--- a/src/ameba/ast/visitors/scope_visitor.cr
+++ b/src/ameba/ast/visitors/scope_visitor.cr
@@ -7,7 +7,6 @@ module Ameba::AST
     RECORD_NODE_NAME = "record"
 
     @scope_queue = [] of Scope
-
     @current_scope : Scope
 
     def initialize(@rule, @source)
@@ -169,7 +168,6 @@ module Ameba::AST
             variable.reference(variable.node, @current_scope).explicit = false
           end
         end
-
         true
       when @current_scope.top_level? && record_macro?(node)
         false
diff --git a/src/ameba/formatter/dot_formatter.cr b/src/ameba/formatter/dot_formatter.cr
index 54fe53ac9..d0f43f7a2 100644
--- a/src/ameba/formatter/dot_formatter.cr
+++ b/src/ameba/formatter/dot_formatter.cr
@@ -89,11 +89,11 @@ module Ameba::Formatter
 
     private def final_message(sources, failed_sources)
       total = sources.size
-      failures = failed_sources.map { |f| f.issues.size }.sum
+      failures = failed_sources.sum(&.issues.size)
       color = failures == 0 ? :green : :red
       s = failures != 1 ? "s" : ""
 
-      "#{total} inspected, #{failures} failure#{s}.\n".colorize color
+      "#{total} inspected, #{failures} failure#{s}.\n".colorize(color)
     end
   end
 end
diff --git a/src/ameba/inline_comments.cr b/src/ameba/inline_comments.cr
index 7d1ec14d9..ae90083cb 100644
--- a/src/ameba/inline_comments.cr
+++ b/src/ameba/inline_comments.cr
@@ -38,7 +38,7 @@ module Ameba
     # ```
     #
     def location_disabled?(location, rule)
-      return false if Rule::SPECIAL.includes?(rule.name)
+      return false if rule.name.in?(Rule::SPECIAL)
       return false unless line_number = location.try &.line_number.try &.- 1
       return false unless line = lines[line_number]?
 
diff --git a/src/ameba/rule/base.cr b/src/ameba/rule/base.cr
index de4c363ff..3292b9952 100644
--- a/src/ameba/rule/base.cr
+++ b/src/ameba/rule/base.cr
@@ -107,11 +107,11 @@ module Ameba::Rule
     # ```
     #
     def special?
-      SPECIAL.includes? name
+      name.in?(SPECIAL)
     end
 
     def ==(other)
-      name == other.try &.name
+      name == other.try(&.name)
     end
 
     def hash
diff --git a/src/ameba/rule/layout/trailing_blank_lines.cr b/src/ameba/rule/layout/trailing_blank_lines.cr
index bf2db9d67..7858687fc 100644
--- a/src/ameba/rule/layout/trailing_blank_lines.cr
+++ b/src/ameba/rule/layout/trailing_blank_lines.cr
@@ -23,9 +23,9 @@ module Ameba::Rule::Layout
       source_lines_size = source_lines.size
       return if source_lines_size == 1 && last_source_line.empty?
 
-      last_line_not_empty = !last_source_line.empty?
-      if source_lines_size >= 1 && (source_lines.last(2).join.strip.empty? || last_line_not_empty)
-        issue_for({source_lines_size - 1, 1}, last_line_not_empty ? MSG_FINAL_NEWLINE : MSG)
+      last_line_empty = last_source_line.empty?
+      if source_lines_size >= 1 && (source_lines.last(2).join.blank? || !last_line_empty)
+        issue_for({source_lines_size - 1, 1}, last_line_empty ? MSG : MSG_FINAL_NEWLINE)
       end
     end
   end
diff --git a/src/ameba/rule/lint/comparison_to_boolean.cr b/src/ameba/rule/lint/comparison_to_boolean.cr
index 474cbc86f..6ea68b88d 100644
--- a/src/ameba/rule/lint/comparison_to_boolean.cr
+++ b/src/ameba/rule/lint/comparison_to_boolean.cr
@@ -30,7 +30,7 @@ module Ameba::Rule::Lint
 
     def test(source, node : Crystal::Call)
       comparison = node.name.in?(OP_NAMES)
-      to_boolean = node.args.first?.try &.is_a?(Crystal::BoolLiteral) ||
+      to_boolean = node.args.first?.try(&.is_a?(Crystal::BoolLiteral)) ||
                    node.obj.is_a?(Crystal::BoolLiteral)
 
       issue_for node, MSG if comparison && to_boolean
diff --git a/src/ameba/rule/lint/empty_expression.cr b/src/ameba/rule/lint/empty_expression.cr
index e3fae35ac..52e5b266d 100644
--- a/src/ameba/rule/lint/empty_expression.cr
+++ b/src/ameba/rule/lint/empty_expression.cr
@@ -31,8 +31,8 @@ module Ameba::Rule::Lint
     include AST::Util
 
     properties do
-      description "Disallows empty expressions"
       enabled false
+      description "Disallows empty expressions"
     end
 
     MSG      = "Avoid empty expression %s"
diff --git a/src/ameba/rule/lint/percent_array.cr b/src/ameba/rule/lint/percent_array.cr
index c8ea02a30..ec0bafcfe 100644
--- a/src/ameba/rule/lint/percent_array.cr
+++ b/src/ameba/rule/lint/percent_array.cr
@@ -26,6 +26,7 @@ module Ameba::Rule::Lint
   struct PercentArrays < Base
     properties do
       description "Disallows some unwanted symbols in percent array literals"
+
       string_array_unwanted_symbols %(,")
       symbol_array_unwanted_symbols %(,:)
     end
diff --git a/src/ameba/rule/lint/shadowed_exception.cr b/src/ameba/rule/lint/shadowed_exception.cr
index 84f2f4356..54a620085 100644
--- a/src/ameba/rule/lint/shadowed_exception.cr
+++ b/src/ameba/rule/lint/shadowed_exception.cr
@@ -51,7 +51,7 @@ module Ameba::Rule::Lint
       previous_exceptions = [] of String
 
       exceptions.reduce([] of String) do |shadowed, excs|
-        excs = excs ? excs.map(&.to_s) : ["Exception"]
+        excs = excs.try(&.map(&.to_s)) || %w[Exception]
 
         if exception_found
           shadowed.concat excs
diff --git a/src/ameba/rule/performance/any_after_filter.cr b/src/ameba/rule/performance/any_after_filter.cr
index da9662eef..ae1e1c83f 100644
--- a/src/ameba/rule/performance/any_after_filter.cr
+++ b/src/ameba/rule/performance/any_after_filter.cr
@@ -26,8 +26,8 @@ module Ameba::Rule::Performance
   # ```
   struct AnyAfterFilter < Base
     properties do
-      filter_names : Array(String) = %w(select reject)
       description "Identifies usage of `any?` calls that follow filters."
+      filter_names : Array(String) = %w(select reject)
     end
 
     ANY_NAME = "any?"
@@ -36,7 +36,7 @@ module Ameba::Rule::Performance
     def test(source, node : Crystal::Call)
       return unless node.name == ANY_NAME && (obj = node.obj)
       return unless obj.is_a?(Crystal::Call) && obj.block && node.block.nil?
-      return unless filter_names.includes?(obj.name)
+      return unless obj.name.in?(filter_names)
 
       issue_for obj.name_location, node.name_end_location, MSG % obj.name
     end
diff --git a/src/ameba/rule/performance/first_last_after_filter.cr b/src/ameba/rule/performance/first_last_after_filter.cr
index 4b251ad8b..79efe463d 100644
--- a/src/ameba/rule/performance/first_last_after_filter.cr
+++ b/src/ameba/rule/performance/first_last_after_filter.cr
@@ -25,8 +25,8 @@ module Ameba::Rule::Performance
   # ```
   struct FirstLastAfterFilter < Base
     properties do
-      filter_names : Array(String) = %w(select)
       description "Identifies usage of `first/last/first?/last?` calls that follow filters."
+      filter_names : Array(String) = %w(select)
     end
 
     CALL_NAMES  = %w(first last first? last?)
@@ -43,10 +43,10 @@ module Ameba::Rule::Performance
     end
 
     def test(source, node : Crystal::Call)
-      return unless CALL_NAMES.includes?(node.name) && (obj = node.obj)
+      return unless node.name.in?(CALL_NAMES) && (obj = node.obj)
       return unless obj.is_a?(Crystal::Call) && obj.block
       return if !node.block.nil? || node.args.any?
-      return unless filter_names.includes?(obj.name)
+      return unless obj.name.in?(filter_names)
 
       message = node.name.includes?(CALL_NAMES.first) ? MSG : MSG_REVERSE
       issue_for obj.name_location, node.name_end_location, message % {obj.name, node.name}
diff --git a/src/ameba/rule/performance/size_after_filter.cr b/src/ameba/rule/performance/size_after_filter.cr
index e825a8f78..0a9238e37 100644
--- a/src/ameba/rule/performance/size_after_filter.cr
+++ b/src/ameba/rule/performance/size_after_filter.cr
@@ -32,8 +32,8 @@ module Ameba::Rule::Performance
   # ```
   struct SizeAfterFilter < Base
     properties do
-      filter_names : Array(String) = %w(select reject)
       description "Identifies usage of `size` calls that follow filter"
+      filter_names : Array(String) = %w(select reject)
     end
 
     SIZE_NAME = "size"
@@ -51,7 +51,7 @@ module Ameba::Rule::Performance
     def test(source, node : Crystal::Call)
       return unless node.name == SIZE_NAME && (obj = node.obj)
       return unless obj.is_a?(Crystal::Call) && obj.block
-      return unless filter_names.includes?(obj.name)
+      return unless obj.name.in?(filter_names)
 
       issue_for obj.name_location, node.name_end_location, MSG % obj.name
     end
diff --git a/src/ameba/rule/style/large_numbers.cr b/src/ameba/rule/style/large_numbers.cr
index caba735f9..02ad38879 100644
--- a/src/ameba/rule/style/large_numbers.cr
+++ b/src/ameba/rule/style/large_numbers.cr
@@ -28,9 +28,9 @@ module Ameba::Rule::Style
   # ```
   struct LargeNumbers < Base
     properties do
+      enabled false
       description "Disallows usage of large numbers without underscore"
       int_min_digits 5
-      enabled false
     end
 
     MSG = "Large numbers should be written with underscores: %s"
@@ -82,7 +82,7 @@ module Ameba::Rule::Style
     end
 
     private def parse_sign(value)
-      if "+-".includes?(value[0])
+      if value[0].in?('+', '-')
         sign = value[0]
         value = value[1..-1]
       end
@@ -90,7 +90,7 @@ module Ameba::Rule::Style
     end
 
     private def parse_suffix(value)
-      if pos = (value =~ /e/ || value =~ /_?(i|u|f)/)
+      if pos = (value =~ /(e|_?(i|u|f))/)
         suffix = value[pos..-1]
         value = value[0..pos - 1]
       end
diff --git a/src/ameba/rule/style/predicate_name.cr b/src/ameba/rule/style/predicate_name.cr
index a7db3ef65..e453f5ad5 100644
--- a/src/ameba/rule/style/predicate_name.cr
+++ b/src/ameba/rule/style/predicate_name.cr
@@ -30,8 +30,8 @@ module Ameba::Rule::Style
   # ```
   struct PredicateName < Base
     properties do
-      description "Disallows tautological predicate names"
       enabled false
+      description "Disallows tautological predicate names"
     end
 
     MSG = "Favour method name '%s?' over '%s'"
diff --git a/src/ameba/rule/style/redundant_begin.cr b/src/ameba/rule/style/redundant_begin.cr
index db6902d8e..cb6e56525 100644
--- a/src/ameba/rule/style/redundant_begin.cr
+++ b/src/ameba/rule/style/redundant_begin.cr
@@ -57,6 +57,7 @@ module Ameba::Rule::Style
   # ```
   struct RedundantBegin < Base
     include AST::Util
+
     properties do
       description "Disallows redundant begin blocks"
     end
@@ -102,6 +103,7 @@ module Ameba::Rule::Style
     private def def_redundant_begin?(code)
       lexer = Crystal::Lexer.new code
       in_body = in_argument_list = false
+
       loop do
         token = lexer.next_token
 
@@ -117,6 +119,7 @@ module Ameba::Rule::Style
         when :NEWLINE
           in_body = true unless in_argument_list
         when :SPACE
+          # ignore
         else
           return false if in_body
         end
diff --git a/src/ameba/rule/style/redundant_next.cr b/src/ameba/rule/style/redundant_next.cr
index fdf62d435..15920a60a 100644
--- a/src/ameba/rule/style/redundant_next.cr
+++ b/src/ameba/rule/style/redundant_next.cr
@@ -99,6 +99,7 @@ module Ameba::Rule::Style
   struct RedundantNext < Base
     properties do
       description "Reports redundant next expressions"
+
       allow_multi_next true
       allow_empty_next true
     end
diff --git a/src/ameba/rule/style/redundant_return.cr b/src/ameba/rule/style/redundant_return.cr
index be226bbbd..3c900283e 100644
--- a/src/ameba/rule/style/redundant_return.cr
+++ b/src/ameba/rule/style/redundant_return.cr
@@ -96,6 +96,7 @@ module Ameba::Rule::Style
   struct RedundantReturn < Base
     properties do
       description "Reports redundant return expressions"
+
       allow_multi_return true
       allow_empty_return true
     end

From 928a260d5187410234bffd66742cefbf4f45b958 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 17 Jan 2021 18:24:49 +0100
Subject: [PATCH 11/37] Remove extraneous blank lines

---
 src/ameba/ast/branch.cr                  | 1 -
 src/ameba/ast/variabling/assignment.cr   | 2 --
 src/ameba/ast/variabling/variable.cr     | 3 ---
 src/ameba/ast/visitors/base_visitor.cr   | 1 -
 src/ameba/formatter/explain_formatter.cr | 1 -
 src/ameba/glob_utils.cr                  | 2 --
 src/ameba/inline_comments.cr             | 2 --
 src/ameba/rule/base.cr                   | 5 -----
 src/ameba/runner.cr                      | 4 ----
 src/ameba/severity.cr                    | 1 -
 src/ameba/source.cr                      | 1 -
 src/ameba/tokenizer.cr                   | 3 ---
 12 files changed, 26 deletions(-)

diff --git a/src/ameba/ast/branch.cr b/src/ameba/ast/branch.cr
index dcca21aa8..647ebafd5 100644
--- a/src/ameba/ast/branch.cr
+++ b/src/ameba/ast/branch.cr
@@ -44,7 +44,6 @@ module Ameba::AST
     #   end
     # end
     # ```
-    #
     def in_loop?
       @parent.loop?
     end
diff --git a/src/ameba/ast/variabling/assignment.cr b/src/ameba/ast/variabling/assignment.cr
index 626e847f3..e8bf04365 100644
--- a/src/ameba/ast/variabling/assignment.cr
+++ b/src/ameba/ast/variabling/assignment.cr
@@ -28,7 +28,6 @@ module Ameba::AST
     # ```
     # Assignment.new(node, variable, scope)
     # ```
-    #
     def initialize(@node, @variable, @scope)
       if scope = @variable.scope
         @branch = Branch.of(@node, scope)
@@ -95,7 +94,6 @@ module Ameba::AST
     #   puts(b)
     # end
     # ```
-    #
     def transformed?
       return false unless (assign = node).is_a?(Crystal::Assign)
       return false unless (value = assign.value).is_a?(Crystal::Call)
diff --git a/src/ameba/ast/variabling/variable.cr b/src/ameba/ast/variabling/variable.cr
index aa9257ac6..ea741e820 100644
--- a/src/ameba/ast/variabling/variable.cr
+++ b/src/ameba/ast/variabling/variable.cr
@@ -27,7 +27,6 @@ module Ameba::AST
     # ```
     # Variable.new(node, scope)
     # ```
-    #
     def initialize(@node, @scope)
     end
 
@@ -45,7 +44,6 @@ module Ameba::AST
     # variable.assign(node2)
     # variable.assignment.size # => 2
     # ```
-    #
     def assign(node, scope)
       assignments << Assignment.new(node, self, scope)
 
@@ -69,7 +67,6 @@ module Ameba::AST
     # variable = Variable.new(node, scope)
     # variable.reference(var_node, some_scope)
     # ```
-    #
     def reference(node : Crystal::Var, scope : Scope)
       Reference.new(node, scope).tap do |reference|
         references << reference
diff --git a/src/ameba/ast/visitors/base_visitor.cr b/src/ameba/ast/visitors/base_visitor.cr
index 20a2ef5af..297bbe5db 100644
--- a/src/ameba/ast/visitors/base_visitor.cr
+++ b/src/ameba/ast/visitors/base_visitor.cr
@@ -15,7 +15,6 @@ module Ameba::AST
     # ```
     # visitor = Ameba::AST::NodeVisitor.new(rule, source)
     # ```
-    #
     def initialize(@rule, @source)
       @source.ast.accept self
     end
diff --git a/src/ameba/formatter/explain_formatter.cr b/src/ameba/formatter/explain_formatter.cr
index 87fb15b6d..4724b087d 100644
--- a/src/ameba/formatter/explain_formatter.cr
+++ b/src/ameba/formatter/explain_formatter.cr
@@ -20,7 +20,6 @@ module Ameba::Formatter
     # ExplainFormatter.new output,
     #   {file: path, line: line_number, column: column_number}
     # ```
-    #
     def initialize(@output, loc)
       @location = Crystal::Location.new(loc[:file], loc[:line], loc[:column])
     end
diff --git a/src/ameba/glob_utils.cr b/src/ameba/glob_utils.cr
index b014bf389..a4a035495 100644
--- a/src/ameba/glob_utils.cr
+++ b/src/ameba/glob_utils.cr
@@ -7,7 +7,6 @@ module Ameba
     # ```
     # find_files_by_globs(["**/*.cr", "!lib"])
     # ```
-    #
     def find_files_by_globs(globs)
       rejected = rejected_globs(globs)
       selected = globs - rejected
@@ -20,7 +19,6 @@ module Ameba
     # ```
     # expand(["spec/*.cr", "src"]) # => all files in src folder + first level specs
     # ```
-    #
     def expand(globs)
       globs.flat_map do |glob|
         glob += "/**/*.cr" if File.directory?(glob)
diff --git a/src/ameba/inline_comments.cr b/src/ameba/inline_comments.cr
index ae90083cb..65f70a248 100644
--- a/src/ameba/inline_comments.cr
+++ b/src/ameba/inline_comments.cr
@@ -36,7 +36,6 @@ module Ameba
     #   Time.epoch(1483859302)
     # end
     # ```
-    #
     def location_disabled?(location, rule)
       return false if rule.name.in?(Rule::SPECIAL)
       return false unless line_number = location.try &.line_number.try &.- 1
@@ -65,7 +64,6 @@ module Ameba
     # line = "# # ameba:disable Rule1, Rule2"
     # parse_inline_directive(line) # => nil
     # ```
-    #
     def parse_inline_directive(line)
       if directive = COMMENT_DIRECTIVE_REGEX.match(line)
         return if commented_out?(line.gsub(directive[0], ""))
diff --git a/src/ameba/rule/base.cr b/src/ameba/rule/base.cr
index 3292b9952..e499452f5 100644
--- a/src/ameba/rule/base.cr
+++ b/src/ameba/rule/base.cr
@@ -50,7 +50,6 @@ module Ameba::Rule
     # source = MyRule.new.catch(source)
     # source.valid?
     # ```
-    #
     def catch(source : Source)
       source.tap { |s| test s }
     end
@@ -65,7 +64,6 @@ module Ameba::Rule
     #
     # MyRule.new.name # => "MyRule"
     # ```
-    #
     def name
       {{@type}}.rule_name
     end
@@ -79,7 +77,6 @@ module Ameba::Rule
     #
     # MyGroup::MyRule.new.group # => "MyGroup"
     # ```
-    #
     def group
       {{@type}}.group_name
     end
@@ -91,7 +88,6 @@ module Ameba::Rule
     # ```
     # my_rule.excluded?(source) # => true or false
     # ```
-    #
     def excluded?(source)
       excluded.try &.any? do |path|
         source.matches_path?(path) ||
@@ -105,7 +101,6 @@ module Ameba::Rule
     # ```
     # my_rule.special? # => true or false
     # ```
-    #
     def special?
       name.in?(SPECIAL)
     end
diff --git a/src/ameba/runner.cr b/src/ameba/runner.cr
index e742dab2c..9e6d29657 100644
--- a/src/ameba/runner.cr
+++ b/src/ameba/runner.cr
@@ -38,7 +38,6 @@ module Ameba
     #
     # Ameba::Runner.new config
     # ```
-    #
     def initialize(config : Config)
       @sources = config.sources
       @formatter = config.formatter
@@ -64,7 +63,6 @@ module Ameba
     # runner = Ameba::Runner.new config
     # runner.run # => returns runner again
     # ```
-    #
     def run
       @formatter.started @sources
       channels = @sources.map { Channel(Exception?).new }
@@ -112,7 +110,6 @@ module Ameba
     # runner.run
     # runner.explain({file: file, line: l, column: c})
     # ```
-    #
     def explain(location, output = STDOUT)
       Formatter::ExplainFormatter.new(output, location).finished @sources
     end
@@ -125,7 +122,6 @@ module Ameba
     # runner.run
     # runner.success? # => true or false
     # ```
-    #
     def success?
       @sources.all? do |source|
         source.issues
diff --git a/src/ameba/severity.cr b/src/ameba/severity.cr
index 3b0e4327c..6444a79db 100644
--- a/src/ameba/severity.cr
+++ b/src/ameba/severity.cr
@@ -23,7 +23,6 @@ module Ameba
     # Severity.parse("convention") # => Severity::Convention
     # Severity.parse("foo-bar")    # => Exception: Incorrect severity name
     # ```
-    #
     def self.parse(name : String)
       super name
     rescue ArgumentError
diff --git a/src/ameba/source.cr b/src/ameba/source.cr
index 70d38627a..2e3f2af4f 100644
--- a/src/ameba/source.cr
+++ b/src/ameba/source.cr
@@ -19,7 +19,6 @@ module Ameba
     # path = "./src/source.cr"
     # Ameba::Source.new File.read(path), path
     # ```
-    #
     def initialize(@code, @path = "")
     end
 
diff --git a/src/ameba/tokenizer.cr b/src/ameba/tokenizer.cr
index e79d12cb4..5703a95ab 100644
--- a/src/ameba/tokenizer.cr
+++ b/src/ameba/tokenizer.cr
@@ -18,7 +18,6 @@ module Ameba
     # source = Ameba::Source.new code, path
     # Ameba::Tokenizer.new(source)
     # ```
-    #
     def initialize(source)
       @lexer = Crystal::Lexer.new source.code
       @lexer.count_whitespace = true
@@ -33,7 +32,6 @@ module Ameba
     # lexer = Crystal::Lexer.new(code)
     # Ameba::Tokenizer.new(lexer)
     # ```
-    #
     def initialize(@lexer : Crystal::Lexer)
     end
 
@@ -44,7 +42,6 @@ module Ameba
     #   puts token
     # end
     # ```
-    #
     def run(&block : Crystal::Token -> _)
       run_normal_state @lexer, &block
       true

From 6898aa8976d4bd9e2172876835d1f0621402326e Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 17 Jan 2021 21:31:53 +0100
Subject: [PATCH 12/37] Fix issue #187 (#189)

* Avoid using `tap` with structs

* Remove extraneous blank lines

* Readability
---
 src/ameba.cr           |  2 --
 src/ameba/ast/util.cr  |  1 -
 src/ameba/cli/cmd.cr   | 10 ++++++++--
 src/ameba/config.cr    |  5 -----
 src/ameba/rule/base.cr |  9 +++++----
 5 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/src/ameba.cr b/src/ameba.cr
index 4649b00c1..f16c62e60 100644
--- a/src/ameba.cr
+++ b/src/ameba.cr
@@ -20,7 +20,6 @@ require "./ameba/formatter/*"
 #
 # Ameba.run config
 # ```
-#
 module Ameba
   extend self
 
@@ -35,7 +34,6 @@ module Ameba
   # Ameba.run
   # Ameba.run config
   # ```
-  #
   def run(config = Config.load)
     Runner.new(config).run
   end
diff --git a/src/ameba/ast/util.cr b/src/ameba/ast/util.cr
index 28f55dd0a..0690e31b1 100644
--- a/src/ameba/ast/util.cr
+++ b/src/ameba/ast/util.cr
@@ -97,7 +97,6 @@ module Ameba::AST::Util
   # ```
   #
   # That's because not all branches return(i.e. `else` is missing).
-  #
   def flow_expression?(node, in_loop = false)
     return true if flow_command? node, in_loop
 
diff --git a/src/ameba/cli/cmd.cr b/src/ameba/cli/cmd.cr
index d32543c45..25d01e76b 100644
--- a/src/ameba/cli/cmd.cr
+++ b/src/ameba/cli/cmd.cr
@@ -121,10 +121,16 @@ module Ameba::Cli
   private def configure_rules(config, opts)
     case
     when only = opts.only
-      config.rules.map! &.tap(&.enabled = false)
+      config.rules.map! do |rule|
+        rule.enabled = false
+        rule
+      end
       config.update_rules(only, enabled: true)
     when opts.all?
-      config.rules.map! &.tap(&.enabled = true)
+      config.rules.map! do |rule|
+        rule.enabled = true
+        rule
+      end
     end
     config.update_rules(opts.except, enabled: false)
   end
diff --git a/src/ameba/config.cr b/src/ameba/config.cr
index c3f7b3390..7661f640a 100644
--- a/src/ameba/config.cr
+++ b/src/ameba/config.cr
@@ -75,7 +75,6 @@ class Ameba::Config
   # ```
   # config = Ameba::Config.load
   # ```
-  #
   def self.load(path = PATH, colors = true)
     Colorize.enabled = colors
     content = File.exists?(path) ? File.read path : "{}"
@@ -97,7 +96,6 @@ class Ameba::Config
   # config.excluded = ["spec"]
   # config.sources # => list of sources pointing to files found by the wildcards
   # ```
-  #
   def sources
     (find_files_by_globs(globs) - find_files_by_globs(excluded))
       .map { |path| Source.new File.read(path), path }
@@ -122,7 +120,6 @@ class Ameba::Config
   # config = Ameba::Config.load
   # config.formatter = :progress
   # ```
-  #
   def formatter=(name : String | Symbol)
     if f = AVAILABLE_FORMATTERS[name]?
       @formatter = f.new
@@ -137,7 +134,6 @@ class Ameba::Config
   # config = Ameba::Config.load
   # config.update_rule "MyRuleName", enabled: false
   # ```
-  #
   def update_rule(name, enabled = true, excluded = nil)
     index = @rules.index { |rule| rule.name == name }
     raise ArgumentError.new("Rule `#{name}` does not exist") unless index
@@ -160,7 +156,6 @@ class Ameba::Config
   # ```
   # config.update_rules %w(Group1 Group2), enabled: true
   # ```
-  #
   def update_rules(names, **args)
     names.try &.each do |name|
       if group = @rule_groups[name]?
diff --git a/src/ameba/rule/base.cr b/src/ameba/rule/base.cr
index e499452f5..ea31a2ca9 100644
--- a/src/ameba/rule/base.cr
+++ b/src/ameba/rule/base.cr
@@ -26,7 +26,6 @@ module Ameba::Rule
   # Enforces rules to implement an abstract `#test` method which
   # is designed to test the source passed in. If source has issues
   # that are tested by this rule, it should add an issue.
-  #
   abstract struct Base
     include Config::RuleConfig
 
@@ -51,7 +50,7 @@ module Ameba::Rule
     # source.valid?
     # ```
     def catch(source : Source)
-      source.tap { |s| test s }
+      source.tap { test source }
     end
 
     # Returns a name of this rule, which is basically a class name.
@@ -151,8 +150,11 @@ module Ameba::Rule
     # ```
     def self.parsed_doc
       source = File.read(path_to_source_file)
-      nodes = Crystal::Parser.new(source).tap(&.wants_doc = true).parse
+      nodes = Crystal::Parser.new(source)
+        .tap(&.wants_doc = true)
+        .parse
       type_name = rule_name.split('/').last?
+
       DocFinder.new(nodes, type_name).doc
     end
 
@@ -185,7 +187,6 @@ module Ameba::Rule
   # ```
   # Ameba::Rule.rules # => [Rule1, Rule2, ....]
   # ```
-  #
   def self.rules
     Base.subclasses
   end

From e9ec91654c2c5f0ad4a1d11bae61032f9f069bea Mon Sep 17 00:00:00 2001
From: Vitalii Elenhaupt <velenhaupt@gmail.com>
Date: Sun, 17 Jan 2021 17:41:34 +0200
Subject: [PATCH 13/37] New Rule: Lint/DuplicatedRequire

closes https://github.com/crystal-ameba/ameba/issues/176
---
 .../visitors/top_level_nodes_visitor_spec.cr  | 17 +++++++
 .../rule/lint/duplicated_require_spec.cr      | 48 +++++++++++++++++++
 .../ast/visitors/top_level_nodes_visitor.cr   | 28 +++++++++++
 src/ameba/rule/lint/duplicated_require.cr     | 31 ++++++++++++
 4 files changed, 124 insertions(+)
 create mode 100644 spec/ameba/ast/visitors/top_level_nodes_visitor_spec.cr
 create mode 100644 spec/ameba/rule/lint/duplicated_require_spec.cr
 create mode 100644 src/ameba/ast/visitors/top_level_nodes_visitor.cr
 create mode 100644 src/ameba/rule/lint/duplicated_require.cr

diff --git a/spec/ameba/ast/visitors/top_level_nodes_visitor_spec.cr b/spec/ameba/ast/visitors/top_level_nodes_visitor_spec.cr
new file mode 100644
index 000000000..0575ff001
--- /dev/null
+++ b/spec/ameba/ast/visitors/top_level_nodes_visitor_spec.cr
@@ -0,0 +1,17 @@
+require "../../../spec_helper"
+
+module Ameba::AST
+  describe TopLevelNodesVisitor do
+    describe "#require_nodes" do
+      it "returns require node" do
+        source = Source.new %(
+          require "foo"
+          def bar; end
+        )
+        visitor = TopLevelNodesVisitor.new(source.ast)
+        visitor.require_nodes.size.should eq 1
+        visitor.require_nodes.first.to_s.should eq %q(require "foo")
+      end
+    end
+  end
+end
diff --git a/spec/ameba/rule/lint/duplicated_require_spec.cr b/spec/ameba/rule/lint/duplicated_require_spec.cr
new file mode 100644
index 000000000..94122d0e7
--- /dev/null
+++ b/spec/ameba/rule/lint/duplicated_require_spec.cr
@@ -0,0 +1,48 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Lint
+  subject = DuplicatedRequire.new
+
+  describe DuplicatedRequire do
+    it "passes if there are no duplicated requires" do
+      source = Source.new %(
+        require "math"
+        require "big"
+        require "big/big_decimal"
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there are a duplicated requires" do
+      source = Source.new %(
+        require "big"
+        require "math"
+        require "big"
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    it "reports rule, pos and message" do
+      source = Source.new %(
+        require "./thing"
+        require "./thing"
+        require "./another_thing"
+        require "./another_thing"
+      ), "source.cr"
+
+      subject.catch(source).should_not be_valid
+
+      issue = source.issues.first
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:2:1"
+      issue.end_location.to_s.should eq ""
+      issue.message.should eq "Duplicated require of `./thing`"
+
+      issue = source.issues.last
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:4:1"
+      issue.end_location.to_s.should eq ""
+      issue.message.should eq "Duplicated require of `./another_thing`"
+    end
+  end
+end
diff --git a/src/ameba/ast/visitors/top_level_nodes_visitor.cr b/src/ameba/ast/visitors/top_level_nodes_visitor.cr
new file mode 100644
index 000000000..6e606cae8
--- /dev/null
+++ b/src/ameba/ast/visitors/top_level_nodes_visitor.cr
@@ -0,0 +1,28 @@
+module Ameba::AST
+  # AST Visitor that visits certain nodes at a top level, which
+  # can characterize the source (i.e. require statements, modules etc.)
+  class TopLevelNodesVisitor < Crystal::Visitor
+    getter require_nodes = [] of Crystal::Require
+
+    # Creates a new instance of visitor
+    def initialize(@scope : Crystal::ASTNode)
+      @scope.accept(self)
+    end
+
+    # :nodoc:
+    def visit(node : Crystal::Require)
+      require_nodes << node
+    end
+
+    # If a top level node is Crystal::Expressions traverse the children.
+    def visit(node : Crystal::Expressions)
+      true
+    end
+
+    # A general visit method for rest of the nodes.
+    # Returns false meaning all child nodes will not be traversed.
+    def visit(node : Crystal::ASTNode)
+      false
+    end
+  end
+end
diff --git a/src/ameba/rule/lint/duplicated_require.cr b/src/ameba/rule/lint/duplicated_require.cr
new file mode 100644
index 000000000..a8b95068e
--- /dev/null
+++ b/src/ameba/rule/lint/duplicated_require.cr
@@ -0,0 +1,31 @@
+module Ameba::Rule::Lint
+  # A rule that reports duplicated require statements.
+  #
+  # ```
+  # require "./thing"
+  # require "./stuff"
+  # require "./thing" # duplicated require
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Lint/DuplicatedRequire:
+  #   Enabled: true
+  # ```
+  struct DuplicatedRequire < Base
+    properties do
+      description "Reports duplicated require statements"
+    end
+
+    MSG = "Duplicated require of `%s`"
+
+    def test(source)
+      nodes = AST::TopLevelNodesVisitor.new(source.ast).require_nodes
+      nodes.each_with_object([] of String) do |node, processed_require_strings|
+        issue_for(node, MSG % node.string) if processed_require_strings.includes?(node.string)
+        processed_require_strings << node.string
+      end
+    end
+  end
+end

From d2fa75280f00f9459b6bd32e402b28a99c0f1ad0 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Mon, 18 Jan 2021 16:42:50 +0100
Subject: [PATCH 14/37] Extend JoinAfterMap to check also calls to
 `sum/product` and rename it to MapInsteadOfBlock (#190)

---
 ...p_spec.cr => map_instead_of_block_spec.cr} |  9 ++++----
 ...n_after_map.cr => map_instead_of_block.cr} | 22 +++++++++++--------
 2 files changed, 18 insertions(+), 13 deletions(-)
 rename spec/ameba/rule/performance/{join_after_map_spec.cr => map_instead_of_block_spec.cr} (87%)
 rename src/ameba/rule/performance/{join_after_map.cr => map_instead_of_block.cr} (54%)

diff --git a/spec/ameba/rule/performance/join_after_map_spec.cr b/spec/ameba/rule/performance/map_instead_of_block_spec.cr
similarity index 87%
rename from spec/ameba/rule/performance/join_after_map_spec.cr
rename to spec/ameba/rule/performance/map_instead_of_block_spec.cr
index 46f5d2501..6a8c468a7 100644
--- a/spec/ameba/rule/performance/join_after_map_spec.cr
+++ b/spec/ameba/rule/performance/map_instead_of_block_spec.cr
@@ -1,13 +1,14 @@
 require "../../../spec_helper"
 
 module Ameba::Rule::Performance
-  subject = JoinAfterMap.new
+  subject = MapInsteadOfBlock.new
 
-  describe JoinAfterMap do
+  describe MapInsteadOfBlock do
     it "passes if there is no potential performance improvements" do
       source = Source.new %(
         (1..3).join(&.to_s)
-        (1..3).join('.', &.to_s)
+        (1..3).sum(&.*(2))
+        (1..3).product(&.*(2))
       )
       subject.catch(source).should be_valid
     end
@@ -52,7 +53,7 @@ module Ameba::Rule::Performance
       issue.rule.should_not be_nil
       issue.location.to_s.should eq "source.cr:1:8"
       issue.end_location.to_s.should eq "source.cr:1:24"
-      issue.message.should eq "Use `join(separator) {...}` instead of `map {...}.join(separator)`"
+      issue.message.should eq "Use `join {...}` instead of `map {...}.join`"
     end
   end
 end
diff --git a/src/ameba/rule/performance/join_after_map.cr b/src/ameba/rule/performance/map_instead_of_block.cr
similarity index 54%
rename from src/ameba/rule/performance/join_after_map.cr
rename to src/ameba/rule/performance/map_instead_of_block.cr
index 3cd742631..334eda2f9 100644
--- a/src/ameba/rule/performance/join_after_map.cr
+++ b/src/ameba/rule/performance/map_instead_of_block.cr
@@ -1,32 +1,35 @@
 module Ameba::Rule::Performance
-  # This rule is used to identify usage of `join` calls that follow `map`.
+  # This rule is used to identify usage of `join/sum/product` calls
+  # that follow `map`.
   #
   # For example, this is considered inefficient:
   #
   # ```
   # (1..3).map(&.to_s).join('.')
+  # (1..3).map(&.*(2)).sum
   # ```
   #
   # And can be written as this:
   #
   # ```
   # (1..3).join('.', &.to_s)
+  # (1..3).sum(&.*(2))
   # ```
   #
   # YAML configuration example:
   #
   # ```
-  # Performance/JoinAfterMap
+  # Performance/MapInsteadOfBlock
   #   Enabled: true
   # ```
-  struct JoinAfterMap < Base
+  struct MapInsteadOfBlock < Base
     properties do
-      description "Identifies usage of `join` calls that follow `map`."
+      description "Identifies usage of `join/sum/product` calls that follow `map`."
     end
 
-    MAP_NAME  = "map"
-    JOIN_NAME = "join"
-    MSG       = "Use `join(separator) {...}` instead of `map {...}.join(separator)`"
+    CALL_NAMES = %w(join sum product)
+    MAP_NAME   = "map"
+    MSG        = "Use `%s {...}` instead of `map {...}.%s`"
 
     def test(source)
       AST::NodeVisitor.new self, source, skip: [
@@ -38,11 +41,12 @@ module Ameba::Rule::Performance
     end
 
     def test(source, node : Crystal::Call)
-      return unless node.name == JOIN_NAME && (obj = node.obj)
+      return unless node.name.in?(CALL_NAMES) && (obj = node.obj)
       return unless obj.is_a?(Crystal::Call) && obj.block
       return unless obj.name == MAP_NAME
 
-      issue_for obj.name_location, node.name_end_location, MSG
+      issue_for obj.name_location, node.name_end_location,
+        MSG % {node.name, node.name}
     end
   end
 end

From b7286dc6738d1790fe655254429b63933e11557f Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Mon, 18 Jan 2021 18:04:12 +0100
Subject: [PATCH 15/37] Add Performance/CompactAfterMap rule

---
 .../performance/compact_after_map_spec.cr     | 50 +++++++++++++++++++
 .../rule/performance/compact_after_map.cr     | 48 ++++++++++++++++++
 2 files changed, 98 insertions(+)
 create mode 100644 spec/ameba/rule/performance/compact_after_map_spec.cr
 create mode 100644 src/ameba/rule/performance/compact_after_map.cr

diff --git a/spec/ameba/rule/performance/compact_after_map_spec.cr b/spec/ameba/rule/performance/compact_after_map_spec.cr
new file mode 100644
index 000000000..ad34c79d1
--- /dev/null
+++ b/spec/ameba/rule/performance/compact_after_map_spec.cr
@@ -0,0 +1,50 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Performance
+  subject = CompactAfterMap.new
+
+  describe CompactAfterMap do
+    it "passes if there is no potential performance improvements" do
+      source = Source.new %(
+        (1..3).compact_map(&.itself)
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "passes if there is map followed by a bang call" do
+      source = Source.new %(
+        (1..3).map(&.itself).compact!
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there is map followed by compact call" do
+      source = Source.new %(
+        (1..3).map(&.itself).compact
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    context "macro" do
+      it "doesn't report in macro scope" do
+        source = Source.new %(
+          {{ [1, 2, 3].map(&.to_s).compact }}
+        )
+        subject.catch(source).should be_valid
+      end
+    end
+
+    it "reports rule, pos and message" do
+      s = Source.new %(
+        (1..3).map(&.itself).compact
+      ), "source.cr"
+      subject.catch(s).should_not be_valid
+      issue = s.issues.first
+
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:1:8"
+      issue.end_location.to_s.should eq "source.cr:1:29"
+      issue.message.should eq "Use `compact_map {...}` instead of `map {...}.compact`"
+    end
+  end
+end
diff --git a/src/ameba/rule/performance/compact_after_map.cr b/src/ameba/rule/performance/compact_after_map.cr
new file mode 100644
index 000000000..f45c32060
--- /dev/null
+++ b/src/ameba/rule/performance/compact_after_map.cr
@@ -0,0 +1,48 @@
+module Ameba::Rule::Performance
+  # This rule is used to identify usage of `compact` calls that follow `map`.
+  #
+  # For example, this is considered inefficient:
+  #
+  # ```
+  # %w[Alice Bob].map(&.match(/^A./)).compact
+  # ```
+  #
+  # And can be written as this:
+  #
+  # ```
+  # %w[Alice Bob].compact_map(&.match(/^A./))
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Performance/CompactAfterMap
+  #   Enabled: true
+  # ```
+  struct CompactAfterMap < Base
+    properties do
+      description "Identifies usage of `compact` calls that follow `map`."
+    end
+
+    COMPACT_NAME = "compact"
+    MAP_NAME     = "map"
+    MSG          = "Use `compact_map {...}` instead of `map {...}.compact`"
+
+    def test(source)
+      AST::NodeVisitor.new self, source, skip: [
+        Crystal::Macro,
+        Crystal::MacroExpression,
+        Crystal::MacroIf,
+        Crystal::MacroFor,
+      ]
+    end
+
+    def test(source, node : Crystal::Call)
+      return unless node.name == COMPACT_NAME && (obj = node.obj)
+      return unless obj.is_a?(Crystal::Call) && obj.block
+      return unless obj.name == MAP_NAME
+
+      issue_for obj.name_location, node.name_end_location, MSG
+    end
+  end
+end

From 23b4b4c4f035f4d3408d0bccc577dfc371a9328e Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Mon, 18 Jan 2021 18:04:54 +0100
Subject: [PATCH 16/37] Add Performance/FlattenAfterMap rule

---
 .../performance/flatten_after_map_spec.cr     | 43 +++++++++++++++++
 .../rule/performance/flatten_after_map.cr     | 48 +++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 spec/ameba/rule/performance/flatten_after_map_spec.cr
 create mode 100644 src/ameba/rule/performance/flatten_after_map.cr

diff --git a/spec/ameba/rule/performance/flatten_after_map_spec.cr b/spec/ameba/rule/performance/flatten_after_map_spec.cr
new file mode 100644
index 000000000..71666c316
--- /dev/null
+++ b/spec/ameba/rule/performance/flatten_after_map_spec.cr
@@ -0,0 +1,43 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Performance
+  subject = FlattenAfterMap.new
+
+  describe FlattenAfterMap do
+    it "passes if there is no potential performance improvements" do
+      source = Source.new %(
+        %w[Alice Bob].flat_map(&.chars)
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there is map followed by flatten call" do
+      source = Source.new %(
+        %w[Alice Bob].map(&.chars).flatten
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    context "macro" do
+      it "doesn't report in macro scope" do
+        source = Source.new %(
+          {{ %w[Alice Bob].map(&.chars).flatten }}
+        )
+        subject.catch(source).should be_valid
+      end
+    end
+
+    it "reports rule, pos and message" do
+      s = Source.new %(
+        %w[Alice Bob].map(&.chars).flatten
+      ), "source.cr"
+      subject.catch(s).should_not be_valid
+      issue = s.issues.first
+
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:1:15"
+      issue.end_location.to_s.should eq "source.cr:1:35"
+      issue.message.should eq "Use `flat_map {...}` instead of `map {...}.flatten`"
+    end
+  end
+end
diff --git a/src/ameba/rule/performance/flatten_after_map.cr b/src/ameba/rule/performance/flatten_after_map.cr
new file mode 100644
index 000000000..c89b77032
--- /dev/null
+++ b/src/ameba/rule/performance/flatten_after_map.cr
@@ -0,0 +1,48 @@
+module Ameba::Rule::Performance
+  # This rule is used to identify usage of `flatten` calls that follow `map`.
+  #
+  # For example, this is considered inefficient:
+  #
+  # ```
+  # %w[Alice Bob].map(&.chars).flatten
+  # ```
+  #
+  # And can be written as this:
+  #
+  # ```
+  # %w[Alice Bob].flat_map(&.chars)
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Performance/FlattenAfterMap
+  #   Enabled: true
+  # ```
+  struct FlattenAfterMap < Base
+    properties do
+      description "Identifies usage of `flatten` calls that follow `map`."
+    end
+
+    FLATTEN_NAME = "flatten"
+    MAP_NAME     = "map"
+    MSG          = "Use `flat_map {...}` instead of `map {...}.flatten`"
+
+    def test(source)
+      AST::NodeVisitor.new self, source, skip: [
+        Crystal::Macro,
+        Crystal::MacroExpression,
+        Crystal::MacroIf,
+        Crystal::MacroFor,
+      ]
+    end
+
+    def test(source, node : Crystal::Call)
+      return unless node.name == FLATTEN_NAME && (obj = node.obj)
+      return unless obj.is_a?(Crystal::Call) && obj.block
+      return unless obj.name == MAP_NAME
+
+      issue_for obj.name_location, node.name_end_location, MSG
+    end
+  end
+end

From ad8f570a047b37577095e924317f67ee6425478a Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Mon, 18 Jan 2021 16:45:35 +0100
Subject: [PATCH 17/37] Change Rule to class

---
 spec/spec_helper.cr                           | 14 ++++++------
 src/ameba/cli/cmd.cr                          | 10 ++-------
 src/ameba/config.cr                           | 22 ++++++++++---------
 src/ameba/rule/base.cr                        | 10 ++++-----
 src/ameba/rule/layout/line_length.cr          |  2 +-
 src/ameba/rule/layout/trailing_blank_lines.cr |  2 +-
 src/ameba/rule/layout/trailing_whitespace.cr  |  2 +-
 src/ameba/rule/lint/bad_directive.cr          |  2 +-
 src/ameba/rule/lint/comparison_to_boolean.cr  |  2 +-
 src/ameba/rule/lint/debugger_statement.cr     |  2 +-
 src/ameba/rule/lint/duplicated_require.cr     |  2 +-
 src/ameba/rule/lint/empty_ensure.cr           |  2 +-
 src/ameba/rule/lint/empty_expression.cr       |  2 +-
 src/ameba/rule/lint/empty_loop.cr             |  2 +-
 src/ameba/rule/lint/hash_duplicated_key.cr    |  2 +-
 src/ameba/rule/lint/literal_in_condition.cr   |  2 +-
 .../rule/lint/literal_in_interpolation.cr     |  2 +-
 src/ameba/rule/lint/percent_array.cr          |  2 +-
 src/ameba/rule/lint/rand_zero.cr              |  2 +-
 .../rule/lint/redundant_string_coercion.cr    |  2 +-
 src/ameba/rule/lint/redundant_with_index.cr   |  2 +-
 src/ameba/rule/lint/redundant_with_object.cr  |  2 +-
 src/ameba/rule/lint/shadowed_argument.cr      |  2 +-
 src/ameba/rule/lint/shadowed_exception.cr     |  2 +-
 .../rule/lint/shadowing_local_outer_var.cr    |  2 +-
 src/ameba/rule/lint/shared_var_in_fiber.cr    |  2 +-
 src/ameba/rule/lint/syntax.cr                 |  2 +-
 .../rule/lint/unneeded_disable_directive.cr   |  2 +-
 src/ameba/rule/lint/unreachable_code.cr       |  2 +-
 src/ameba/rule/lint/unused_argument.cr        |  2 +-
 src/ameba/rule/lint/useless_assign.cr         |  2 +-
 .../rule/lint/useless_condition_in_when.cr    |  2 +-
 .../rule/metrics/cyclomatic_complexity.cr     |  2 +-
 .../rule/performance/any_after_filter.cr      |  2 +-
 .../rule/performance/compact_after_map.cr     |  2 +-
 .../performance/first_last_after_filter.cr    |  2 +-
 .../rule/performance/flatten_after_map.cr     |  2 +-
 .../rule/performance/map_instead_of_block.cr  |  2 +-
 .../rule/performance/size_after_filter.cr     |  2 +-
 src/ameba/rule/style/constant_names.cr        |  2 +-
 src/ameba/rule/style/is_a_nil.cr              |  2 +-
 src/ameba/rule/style/large_numbers.cr         |  2 +-
 src/ameba/rule/style/method_names.cr          |  2 +-
 .../style/negated_conditions_in_unless.cr     |  2 +-
 src/ameba/rule/style/predicate_name.cr        |  2 +-
 src/ameba/rule/style/redundant_begin.cr       |  2 +-
 src/ameba/rule/style/redundant_next.cr        |  2 +-
 src/ameba/rule/style/redundant_return.cr      |  2 +-
 src/ameba/rule/style/type_names.cr            |  2 +-
 src/ameba/rule/style/unless_else.cr           |  2 +-
 src/ameba/rule/style/variable_names.cr        |  2 +-
 src/ameba/rule/style/while_true.cr            |  2 +-
 52 files changed, 74 insertions(+), 78 deletions(-)

diff --git a/spec/spec_helper.cr b/spec/spec_helper.cr
index a1739becc..3f106efbb 100644
--- a/spec/spec_helper.cr
+++ b/spec/spec_helper.cr
@@ -3,7 +3,7 @@ require "../src/ameba"
 
 module Ameba
   # Dummy Rule which does nothing.
-  struct DummyRule < Rule::Base
+  class DummyRule < Rule::Base
     properties do
       description : String = "Dummy rule that does nothing."
     end
@@ -35,7 +35,7 @@ module Ameba
     end
   end
 
-  struct NamedRule < Rule::Base
+  class NamedRule < Rule::Base
     properties do
       description "A rule with a custom name."
     end
@@ -45,7 +45,7 @@ module Ameba
     end
   end
 
-  struct ErrorRule < Rule::Base
+  class ErrorRule < Rule::Base
     properties do
       description "Always adds an error at 1:1"
     end
@@ -55,7 +55,7 @@ module Ameba
     end
   end
 
-  struct ScopeRule < Rule::Base
+  class ScopeRule < Rule::Base
     @[YAML::Field(ignore: true)]
     getter scopes = [] of AST::Scope
 
@@ -68,7 +68,7 @@ module Ameba
     end
   end
 
-  struct FlowExpressionRule < Rule::Base
+  class FlowExpressionRule < Rule::Base
     @[YAML::Field(ignore: true)]
     getter expressions = [] of AST::FlowExpression
 
@@ -81,7 +81,7 @@ module Ameba
     end
   end
 
-  struct RedundantControlExpressionRule < Rule::Base
+  class RedundantControlExpressionRule < Rule::Base
     @[YAML::Field(ignore: true)]
     getter nodes = [] of Crystal::ASTNode
 
@@ -95,7 +95,7 @@ module Ameba
   end
 
   # A rule that always raises an error
-  struct RaiseRule < Rule::Base
+  class RaiseRule < Rule::Base
     property should_raise = false
 
     properties do
diff --git a/src/ameba/cli/cmd.cr b/src/ameba/cli/cmd.cr
index 25d01e76b..3f80899eb 100644
--- a/src/ameba/cli/cmd.cr
+++ b/src/ameba/cli/cmd.cr
@@ -121,16 +121,10 @@ module Ameba::Cli
   private def configure_rules(config, opts)
     case
     when only = opts.only
-      config.rules.map! do |rule|
-        rule.enabled = false
-        rule
-      end
+      config.rules.each(&.enabled = false)
       config.update_rules(only, enabled: true)
     when opts.all?
-      config.rules.map! do |rule|
-        rule.enabled = true
-        rule
-      end
+      config.rules.each(&.enabled = true)
     end
     config.update_rules(opts.except, enabled: false)
   end
diff --git a/src/ameba/config.cr b/src/ameba/config.cr
index 7661f640a..381f87255 100644
--- a/src/ameba/config.cr
+++ b/src/ameba/config.cr
@@ -135,13 +135,12 @@ class Ameba::Config
   # config.update_rule "MyRuleName", enabled: false
   # ```
   def update_rule(name, enabled = true, excluded = nil)
-    index = @rules.index { |rule| rule.name == name }
-    raise ArgumentError.new("Rule `#{name}` does not exist") unless index
+    rule = @rules.find(&.name.==(name))
+    raise ArgumentError.new("Rule `#{name}` does not exist") unless rule
 
-    rule = @rules[index]
-    rule.enabled = enabled
-    rule.excluded = excluded
-    @rules[index] = rule
+    rule
+      .tap(&.enabled = enabled)
+      .tap(&.excluded = excluded)
   end
 
   # Updates rules properties.
@@ -156,12 +155,15 @@ class Ameba::Config
   # ```
   # config.update_rules %w(Group1 Group2), enabled: true
   # ```
-  def update_rules(names, **args)
+  def update_rules(names, enabled = true, excluded = nil)
     names.try &.each do |name|
-      if group = @rule_groups[name]?
-        group.each { |rule| update_rule(rule.name, **args) }
+      if rules = @rule_groups[name]?
+        rules.each do |rule|
+          rule.enabled = enabled
+          rule.excluded = excluded
+        end
       else
-        update_rule name, **args
+        update_rule name, enabled, excluded
       end
     end
   end
diff --git a/src/ameba/rule/base.cr b/src/ameba/rule/base.cr
index ea31a2ca9..414c469ab 100644
--- a/src/ameba/rule/base.cr
+++ b/src/ameba/rule/base.cr
@@ -10,7 +10,7 @@ module Ameba::Rule
   # inherits from this struct:
   #
   # ```
-  # struct MyRule < Ameba::Rule::Base
+  # class MyRule < Ameba::Rule::Base
   #   def test(source)
   #     if invalid?(source)
   #       issue_for line, column, "Something wrong."
@@ -26,7 +26,7 @@ module Ameba::Rule
   # Enforces rules to implement an abstract `#test` method which
   # is designed to test the source passed in. If source has issues
   # that are tested by this rule, it should add an issue.
-  abstract struct Base
+  abstract class Base
     include Config::RuleConfig
 
     # This method is designed to test the source passed in. If source has issues
@@ -56,7 +56,7 @@ module Ameba::Rule
     # Returns a name of this rule, which is basically a class name.
     #
     # ```
-    # struct MyRule < Ameba::Rule::Base
+    # class MyRule < Ameba::Rule::Base
     #   def test(source)
     #   end
     # end
@@ -70,7 +70,7 @@ module Ameba::Rule
     # Returns a group this rule belong to.
     #
     # ```
-    # struct MyGroup::MyRule < Ameba::Rule::Base
+    # class MyGroup::MyRule < Ameba::Rule::Base
     #   # ...
     # end
     #
@@ -140,7 +140,7 @@ module Ameba::Rule
     # module Ameba
     #   # This is a test rule.
     #   # Does nothing.
-    #   struct MyRule < Ameba::Rule::Base
+    #   class MyRule < Ameba::Rule::Base
     #     def test(source)
     #     end
     #   end
diff --git a/src/ameba/rule/layout/line_length.cr b/src/ameba/rule/layout/line_length.cr
index df8430701..41eb76fa4 100644
--- a/src/ameba/rule/layout/line_length.cr
+++ b/src/ameba/rule/layout/line_length.cr
@@ -8,7 +8,7 @@ module Ameba::Rule::Layout
   #   Enabled: true
   #   MaxLength: 100
   # ```
-  struct LineLength < Base
+  class LineLength < Base
     properties do
       enabled false
       description "Disallows lines longer than `MaxLength` number of symbols"
diff --git a/src/ameba/rule/layout/trailing_blank_lines.cr b/src/ameba/rule/layout/trailing_blank_lines.cr
index 7858687fc..a133ebb8c 100644
--- a/src/ameba/rule/layout/trailing_blank_lines.cr
+++ b/src/ameba/rule/layout/trailing_blank_lines.cr
@@ -7,7 +7,7 @@ module Ameba::Rule::Layout
   # Layout/TrailingBlankLines:
   #   Enabled: true
   # ```
-  struct TrailingBlankLines < Base
+  class TrailingBlankLines < Base
     properties do
       description "Disallows trailing blank lines"
     end
diff --git a/src/ameba/rule/layout/trailing_whitespace.cr b/src/ameba/rule/layout/trailing_whitespace.cr
index 77456c1a7..a80a56ec1 100644
--- a/src/ameba/rule/layout/trailing_whitespace.cr
+++ b/src/ameba/rule/layout/trailing_whitespace.cr
@@ -7,7 +7,7 @@ module Ameba::Rule::Layout
   # Layout/TrailingWhitespace:
   #   Enabled: true
   # ```
-  struct TrailingWhitespace < Base
+  class TrailingWhitespace < Base
     properties do
       description "Disallows trailing whitespaces"
     end
diff --git a/src/ameba/rule/lint/bad_directive.cr b/src/ameba/rule/lint/bad_directive.cr
index 1fcfd896a..3d70c2d50 100644
--- a/src/ameba/rule/lint/bad_directive.cr
+++ b/src/ameba/rule/lint/bad_directive.cr
@@ -17,7 +17,7 @@ module Ameba::Rule::Lint
   # Lint/BadDirective:
   #   Enabled: true
   # ```
-  struct BadDirective < Base
+  class BadDirective < Base
     properties do
       description "Reports bad comment directives"
     end
diff --git a/src/ameba/rule/lint/comparison_to_boolean.cr b/src/ameba/rule/lint/comparison_to_boolean.cr
index 6ea68b88d..d95d68d70 100644
--- a/src/ameba/rule/lint/comparison_to_boolean.cr
+++ b/src/ameba/rule/lint/comparison_to_boolean.cr
@@ -19,7 +19,7 @@ module Ameba::Rule::Lint
   # Lint/ComparisonToBoolean:
   #   Enabled: true
   # ```
-  struct ComparisonToBoolean < Base
+  class ComparisonToBoolean < Base
     properties do
       enabled false
       description "Disallows comparison to booleans"
diff --git a/src/ameba/rule/lint/debugger_statement.cr b/src/ameba/rule/lint/debugger_statement.cr
index b5131384c..da478cbb4 100644
--- a/src/ameba/rule/lint/debugger_statement.cr
+++ b/src/ameba/rule/lint/debugger_statement.cr
@@ -10,7 +10,7 @@ module Ameba::Rule::Lint
   # Lint/DebuggerStatement:
   #   Enabled: true
   # ```
-  struct DebuggerStatement < Base
+  class DebuggerStatement < Base
     properties do
       description "Disallows calls to debugger"
     end
diff --git a/src/ameba/rule/lint/duplicated_require.cr b/src/ameba/rule/lint/duplicated_require.cr
index a8b95068e..0e33dbb03 100644
--- a/src/ameba/rule/lint/duplicated_require.cr
+++ b/src/ameba/rule/lint/duplicated_require.cr
@@ -13,7 +13,7 @@ module Ameba::Rule::Lint
   # Lint/DuplicatedRequire:
   #   Enabled: true
   # ```
-  struct DuplicatedRequire < Base
+  class DuplicatedRequire < Base
     properties do
       description "Reports duplicated require statements"
     end
diff --git a/src/ameba/rule/lint/empty_ensure.cr b/src/ameba/rule/lint/empty_ensure.cr
index 94deeb369..e363f824b 100644
--- a/src/ameba/rule/lint/empty_ensure.cr
+++ b/src/ameba/rule/lint/empty_ensure.cr
@@ -38,7 +38,7 @@ module Ameba::Rule::Lint
   # Lint/EmptyEnsure
   #   Enabled: true
   # ```
-  struct EmptyEnsure < Base
+  class EmptyEnsure < Base
     properties do
       description "Disallows empty ensure statement"
     end
diff --git a/src/ameba/rule/lint/empty_expression.cr b/src/ameba/rule/lint/empty_expression.cr
index 52e5b266d..89ca5fdcf 100644
--- a/src/ameba/rule/lint/empty_expression.cr
+++ b/src/ameba/rule/lint/empty_expression.cr
@@ -27,7 +27,7 @@ module Ameba::Rule::Lint
   # Lint/EmptyExpression:
   #   Enabled: true
   # ```
-  struct EmptyExpression < Base
+  class EmptyExpression < Base
     include AST::Util
 
     properties do
diff --git a/src/ameba/rule/lint/empty_loop.cr b/src/ameba/rule/lint/empty_loop.cr
index 19eafd2fe..b58e23664 100644
--- a/src/ameba/rule/lint/empty_loop.cr
+++ b/src/ameba/rule/lint/empty_loop.cr
@@ -37,7 +37,7 @@ module Ameba::Rule::Lint
   # Lint/EmptyLoop:
   #   Enabled: true
   # ```
-  struct EmptyLoop < Base
+  class EmptyLoop < Base
     include AST::Util
 
     properties do
diff --git a/src/ameba/rule/lint/hash_duplicated_key.cr b/src/ameba/rule/lint/hash_duplicated_key.cr
index 6a581b4f5..c8ffcb4e6 100644
--- a/src/ameba/rule/lint/hash_duplicated_key.cr
+++ b/src/ameba/rule/lint/hash_duplicated_key.cr
@@ -19,7 +19,7 @@ module Ameba::Rule::Lint
   # Lint/HashDuplicatedKey:
   #   Enabled: true
   # ```
-  struct HashDuplicatedKey < Base
+  class HashDuplicatedKey < Base
     properties do
       description "Disallows duplicated keys in hash literals"
     end
diff --git a/src/ameba/rule/lint/literal_in_condition.cr b/src/ameba/rule/lint/literal_in_condition.cr
index 642350d6f..fc3ce23a2 100644
--- a/src/ameba/rule/lint/literal_in_condition.cr
+++ b/src/ameba/rule/lint/literal_in_condition.cr
@@ -19,7 +19,7 @@ module Ameba::Rule::Lint
   # Lint/LiteralInCondition:
   #   Enabled: true
   # ```
-  struct LiteralInCondition < Base
+  class LiteralInCondition < Base
     include AST::Util
 
     properties do
diff --git a/src/ameba/rule/lint/literal_in_interpolation.cr b/src/ameba/rule/lint/literal_in_interpolation.cr
index 6c96c1c87..a8683d128 100644
--- a/src/ameba/rule/lint/literal_in_interpolation.cr
+++ b/src/ameba/rule/lint/literal_in_interpolation.cr
@@ -15,7 +15,7 @@ module Ameba::Rule::Lint
   # Lint/LiteralInInterpolation
   #   Enabled: true
   # ```
-  struct LiteralInInterpolation < Base
+  class LiteralInInterpolation < Base
     include AST::Util
 
     properties do
diff --git a/src/ameba/rule/lint/percent_array.cr b/src/ameba/rule/lint/percent_array.cr
index ec0bafcfe..3109fa151 100644
--- a/src/ameba/rule/lint/percent_array.cr
+++ b/src/ameba/rule/lint/percent_array.cr
@@ -23,7 +23,7 @@ module Ameba::Rule::Lint
   #   StringArrayUnwantedSymbols: ',"'
   #   SymbolArrayUnwantedSymbols: ',:'
   # ```
-  struct PercentArrays < Base
+  class PercentArrays < Base
     properties do
       description "Disallows some unwanted symbols in percent array literals"
 
diff --git a/src/ameba/rule/lint/rand_zero.cr b/src/ameba/rule/lint/rand_zero.cr
index ad1843caf..565450bf0 100644
--- a/src/ameba/rule/lint/rand_zero.cr
+++ b/src/ameba/rule/lint/rand_zero.cr
@@ -22,7 +22,7 @@ module Ameba::Rule::Lint
   # Lint/RandZero:
   #   Enabled: true
   # ```
-  struct RandZero < Base
+  class RandZero < Base
     properties do
       description "Disallows rand zero calls"
     end
diff --git a/src/ameba/rule/lint/redundant_string_coercion.cr b/src/ameba/rule/lint/redundant_string_coercion.cr
index f451e9eac..0273e6d9b 100644
--- a/src/ameba/rule/lint/redundant_string_coercion.cr
+++ b/src/ameba/rule/lint/redundant_string_coercion.cr
@@ -20,7 +20,7 @@ module Ameba::Rule::Lint
   # Lint/RedundantStringCoersion
   #   Enabled: true
   # ```
-  struct RedundantStringCoercion < Base
+  class RedundantStringCoercion < Base
     include AST::Util
 
     properties do
diff --git a/src/ameba/rule/lint/redundant_with_index.cr b/src/ameba/rule/lint/redundant_with_index.cr
index 35d3ffc91..6f6229861 100644
--- a/src/ameba/rule/lint/redundant_with_index.cr
+++ b/src/ameba/rule/lint/redundant_with_index.cr
@@ -26,7 +26,7 @@ module Ameba::Rule::Lint
   # Lint/RedundantWithIndex:
   #   Enabled: true
   # ```
-  struct RedundantWithIndex < Base
+  class RedundantWithIndex < Base
     properties do
       description "Disallows redundant `with_index` calls"
     end
diff --git a/src/ameba/rule/lint/redundant_with_object.cr b/src/ameba/rule/lint/redundant_with_object.cr
index 585e63849..9acf0bf8d 100644
--- a/src/ameba/rule/lint/redundant_with_object.cr
+++ b/src/ameba/rule/lint/redundant_with_object.cr
@@ -27,7 +27,7 @@ module Ameba::Rule::Lint
   # Lint/RedundantWithObject:
   #   Enabled: true
   # ```
-  struct RedundantWithObject < Base
+  class RedundantWithObject < Base
     properties do
       description "Disallows redundant `with_object` calls"
     end
diff --git a/src/ameba/rule/lint/shadowed_argument.cr b/src/ameba/rule/lint/shadowed_argument.cr
index 444c24e45..c21c1daed 100644
--- a/src/ameba/rule/lint/shadowed_argument.cr
+++ b/src/ameba/rule/lint/shadowed_argument.cr
@@ -35,7 +35,7 @@ module Ameba::Rule::Lint
   # Lint/ShadowedArgument:
   #   Enabled: true
   # ```
-  struct ShadowedArgument < Base
+  class ShadowedArgument < Base
     properties do
       description "Disallows shadowed arguments"
     end
diff --git a/src/ameba/rule/lint/shadowed_exception.cr b/src/ameba/rule/lint/shadowed_exception.cr
index 54a620085..6e10de9d3 100644
--- a/src/ameba/rule/lint/shadowed_exception.cr
+++ b/src/ameba/rule/lint/shadowed_exception.cr
@@ -33,7 +33,7 @@ module Ameba::Rule::Lint
   # Lint/ShadowedException:
   #   Enabled: true
   # ```
-  struct ShadowedException < Base
+  class ShadowedException < Base
     properties do
       description "Disallows rescued exception that get shadowed"
     end
diff --git a/src/ameba/rule/lint/shadowing_local_outer_var.cr b/src/ameba/rule/lint/shadowing_local_outer_var.cr
index dbfc4da05..8f70a2858 100644
--- a/src/ameba/rule/lint/shadowing_local_outer_var.cr
+++ b/src/ameba/rule/lint/shadowing_local_outer_var.cr
@@ -30,7 +30,7 @@ module Ameba::Rule::Lint
   # Lint/ShadowingOuterLocalVar:
   #   Enabled: true
   # ```
-  struct ShadowingOuterLocalVar < Base
+  class ShadowingOuterLocalVar < Base
     properties do
       description "Disallows the usage of the same name as outer local variables" \
                   " for block or proc arguments."
diff --git a/src/ameba/rule/lint/shared_var_in_fiber.cr b/src/ameba/rule/lint/shared_var_in_fiber.cr
index 56cc465ba..2e57c7125 100644
--- a/src/ameba/rule/lint/shared_var_in_fiber.cr
+++ b/src/ameba/rule/lint/shared_var_in_fiber.cr
@@ -49,7 +49,7 @@ module Ameba::Rule::Lint
   # Lint/SharedVarInFiber:
   #   Enabled: true
   # ```
-  struct SharedVarInFiber < Base
+  class SharedVarInFiber < Base
     properties do
       description "Disallows shared variables in fibers."
     end
diff --git a/src/ameba/rule/lint/syntax.cr b/src/ameba/rule/lint/syntax.cr
index 6c4efa48f..6fbaddda2 100644
--- a/src/ameba/rule/lint/syntax.cr
+++ b/src/ameba/rule/lint/syntax.cr
@@ -18,7 +18,7 @@ module Ameba::Rule::Lint
   # rescue e : Exception
   # end
   # ```
-  struct Syntax < Base
+  class Syntax < Base
     properties do
       description "Reports invalid Crystal syntax"
       severity Ameba::Severity::Error
diff --git a/src/ameba/rule/lint/unneeded_disable_directive.cr b/src/ameba/rule/lint/unneeded_disable_directive.cr
index 7016f7699..d6d8fc2c2 100644
--- a/src/ameba/rule/lint/unneeded_disable_directive.cr
+++ b/src/ameba/rule/lint/unneeded_disable_directive.cr
@@ -24,7 +24,7 @@ module Ameba::Rule::Lint
   # Lint/UnneededDisableDirective
   #   Enabled: true
   # ```
-  struct UnneededDisableDirective < Base
+  class UnneededDisableDirective < Base
     properties do
       description "Reports unneeded disable directives in comments"
     end
diff --git a/src/ameba/rule/lint/unreachable_code.cr b/src/ameba/rule/lint/unreachable_code.cr
index 69f3731f2..dc7e34647 100644
--- a/src/ameba/rule/lint/unreachable_code.cr
+++ b/src/ameba/rule/lint/unreachable_code.cr
@@ -41,7 +41,7 @@ module Ameba::Rule::Lint
   # Lint/UnreachableCode:
   #   Enabled: true
   # ```
-  struct UnreachableCode < Base
+  class UnreachableCode < Base
     include AST::Util
 
     properties do
diff --git a/src/ameba/rule/lint/unused_argument.cr b/src/ameba/rule/lint/unused_argument.cr
index 9615ec4cc..16d860492 100644
--- a/src/ameba/rule/lint/unused_argument.cr
+++ b/src/ameba/rule/lint/unused_argument.cr
@@ -24,7 +24,7 @@ module Ameba::Rule::Lint
   #   IgnoreBlocks: false
   #   IgnoreProcs: false
   # ```
-  struct UnusedArgument < Base
+  class UnusedArgument < Base
     properties do
       description "Disallows unused arguments"
 
diff --git a/src/ameba/rule/lint/useless_assign.cr b/src/ameba/rule/lint/useless_assign.cr
index 23f69d4f2..5b06763cd 100644
--- a/src/ameba/rule/lint/useless_assign.cr
+++ b/src/ameba/rule/lint/useless_assign.cr
@@ -25,7 +25,7 @@ module Ameba::Rule::Lint
   # Lint/UselessAssign:
   #   Enabled: true
   # ```
-  struct UselessAssign < Base
+  class UselessAssign < Base
     properties do
       description "Disallows useless variable assignments"
     end
diff --git a/src/ameba/rule/lint/useless_condition_in_when.cr b/src/ameba/rule/lint/useless_condition_in_when.cr
index f9f40ca65..7cf7784dd 100644
--- a/src/ameba/rule/lint/useless_condition_in_when.cr
+++ b/src/ameba/rule/lint/useless_condition_in_when.cr
@@ -30,7 +30,7 @@ module Ameba::Rule::Lint
   # Lint/UselessConditionInWhen:
   #   Enabled: true
   # ```
-  struct UselessConditionInWhen < Base
+  class UselessConditionInWhen < Base
     properties do
       description "Disallows useless conditions in when"
     end
diff --git a/src/ameba/rule/metrics/cyclomatic_complexity.cr b/src/ameba/rule/metrics/cyclomatic_complexity.cr
index 9ce2bce4f..1047df670 100644
--- a/src/ameba/rule/metrics/cyclomatic_complexity.cr
+++ b/src/ameba/rule/metrics/cyclomatic_complexity.cr
@@ -8,7 +8,7 @@ module Ameba::Rule::Metrics
   #   Enabled: true
   #   MaxComplexity: 10
   # ```
-  struct CyclomaticComplexity < Base
+  class CyclomaticComplexity < Base
     properties do
       description "Disallows methods with a cyclomatic complexity higher than `MaxComplexity`"
       max_complexity 10
diff --git a/src/ameba/rule/performance/any_after_filter.cr b/src/ameba/rule/performance/any_after_filter.cr
index ae1e1c83f..bdc9c1e7f 100644
--- a/src/ameba/rule/performance/any_after_filter.cr
+++ b/src/ameba/rule/performance/any_after_filter.cr
@@ -24,7 +24,7 @@ module Ameba::Rule::Performance
   #     - select
   #     - reject
   # ```
-  struct AnyAfterFilter < Base
+  class AnyAfterFilter < Base
     properties do
       description "Identifies usage of `any?` calls that follow filters."
       filter_names : Array(String) = %w(select reject)
diff --git a/src/ameba/rule/performance/compact_after_map.cr b/src/ameba/rule/performance/compact_after_map.cr
index f45c32060..77f542cf2 100644
--- a/src/ameba/rule/performance/compact_after_map.cr
+++ b/src/ameba/rule/performance/compact_after_map.cr
@@ -19,7 +19,7 @@ module Ameba::Rule::Performance
   # Performance/CompactAfterMap
   #   Enabled: true
   # ```
-  struct CompactAfterMap < Base
+  class CompactAfterMap < Base
     properties do
       description "Identifies usage of `compact` calls that follow `map`."
     end
diff --git a/src/ameba/rule/performance/first_last_after_filter.cr b/src/ameba/rule/performance/first_last_after_filter.cr
index 79efe463d..4333bd6d5 100644
--- a/src/ameba/rule/performance/first_last_after_filter.cr
+++ b/src/ameba/rule/performance/first_last_after_filter.cr
@@ -23,7 +23,7 @@ module Ameba::Rule::Performance
   #   FilterNames:
   #     - select
   # ```
-  struct FirstLastAfterFilter < Base
+  class FirstLastAfterFilter < Base
     properties do
       description "Identifies usage of `first/last/first?/last?` calls that follow filters."
       filter_names : Array(String) = %w(select)
diff --git a/src/ameba/rule/performance/flatten_after_map.cr b/src/ameba/rule/performance/flatten_after_map.cr
index c89b77032..631c656d0 100644
--- a/src/ameba/rule/performance/flatten_after_map.cr
+++ b/src/ameba/rule/performance/flatten_after_map.cr
@@ -19,7 +19,7 @@ module Ameba::Rule::Performance
   # Performance/FlattenAfterMap
   #   Enabled: true
   # ```
-  struct FlattenAfterMap < Base
+  class FlattenAfterMap < Base
     properties do
       description "Identifies usage of `flatten` calls that follow `map`."
     end
diff --git a/src/ameba/rule/performance/map_instead_of_block.cr b/src/ameba/rule/performance/map_instead_of_block.cr
index 334eda2f9..5e8036173 100644
--- a/src/ameba/rule/performance/map_instead_of_block.cr
+++ b/src/ameba/rule/performance/map_instead_of_block.cr
@@ -22,7 +22,7 @@ module Ameba::Rule::Performance
   # Performance/MapInsteadOfBlock
   #   Enabled: true
   # ```
-  struct MapInsteadOfBlock < Base
+  class MapInsteadOfBlock < Base
     properties do
       description "Identifies usage of `join/sum/product` calls that follow `map`."
     end
diff --git a/src/ameba/rule/performance/size_after_filter.cr b/src/ameba/rule/performance/size_after_filter.cr
index 0a9238e37..f7a2fbbb3 100644
--- a/src/ameba/rule/performance/size_after_filter.cr
+++ b/src/ameba/rule/performance/size_after_filter.cr
@@ -30,7 +30,7 @@ module Ameba::Rule::Performance
   #     - select
   #     - reject
   # ```
-  struct SizeAfterFilter < Base
+  class SizeAfterFilter < Base
     properties do
       description "Identifies usage of `size` calls that follow filter"
       filter_names : Array(String) = %w(select reject)
diff --git a/src/ameba/rule/style/constant_names.cr b/src/ameba/rule/style/constant_names.cr
index 180ed8be1..e5182efb7 100644
--- a/src/ameba/rule/style/constant_names.cr
+++ b/src/ameba/rule/style/constant_names.cr
@@ -21,7 +21,7 @@ module Ameba::Rule::Style
   # Style/ConstantNames:
   #   Enabled: true
   # ```
-  struct ConstantNames < Base
+  class ConstantNames < Base
     properties do
       description "Enforces constant names to be in screaming case"
     end
diff --git a/src/ameba/rule/style/is_a_nil.cr b/src/ameba/rule/style/is_a_nil.cr
index 4848cd2f9..72568b3a4 100644
--- a/src/ameba/rule/style/is_a_nil.cr
+++ b/src/ameba/rule/style/is_a_nil.cr
@@ -19,7 +19,7 @@ module Ameba::Rule::Style
   # Style/IsANil:
   #   Enabled: true
   # ```
-  struct IsANil < Base
+  class IsANil < Base
     properties do
       description "Disallows calls to `is_a?(Nil)` in favor of `nil?`"
     end
diff --git a/src/ameba/rule/style/large_numbers.cr b/src/ameba/rule/style/large_numbers.cr
index 02ad38879..e36c4c0fa 100644
--- a/src/ameba/rule/style/large_numbers.cr
+++ b/src/ameba/rule/style/large_numbers.cr
@@ -26,7 +26,7 @@ module Ameba::Rule::Style
   #   Enabled: true
   #   IntMinDigits: 5 # i.e. integers higher than 9999
   # ```
-  struct LargeNumbers < Base
+  class LargeNumbers < Base
     properties do
       enabled false
       description "Disallows usage of large numbers without underscore"
diff --git a/src/ameba/rule/style/method_names.cr b/src/ameba/rule/style/method_names.cr
index c53a0f9af..112ffbd7f 100644
--- a/src/ameba/rule/style/method_names.cr
+++ b/src/ameba/rule/style/method_names.cr
@@ -37,7 +37,7 @@ module Ameba::Rule::Style
   # Style/MethodNames:
   #   Enabled: true
   # ```
-  struct MethodNames < Base
+  class MethodNames < Base
     properties do
       description "Enforces method names to be in underscored case"
     end
diff --git a/src/ameba/rule/style/negated_conditions_in_unless.cr b/src/ameba/rule/style/negated_conditions_in_unless.cr
index 2780e228c..653a574be 100644
--- a/src/ameba/rule/style/negated_conditions_in_unless.cr
+++ b/src/ameba/rule/style/negated_conditions_in_unless.cr
@@ -26,7 +26,7 @@ module Ameba::Rule::Style
   # Style/NegatedConditionsInUnless:
   #   Enabled: true
   # ```
-  struct NegatedConditionsInUnless < Base
+  class NegatedConditionsInUnless < Base
     properties do
       description "Disallows negated conditions in unless"
     end
diff --git a/src/ameba/rule/style/predicate_name.cr b/src/ameba/rule/style/predicate_name.cr
index e453f5ad5..24afebc1b 100644
--- a/src/ameba/rule/style/predicate_name.cr
+++ b/src/ameba/rule/style/predicate_name.cr
@@ -28,7 +28,7 @@ module Ameba::Rule::Style
   # Style/PredicateName:
   #   Enabled: true
   # ```
-  struct PredicateName < Base
+  class PredicateName < Base
     properties do
       enabled false
       description "Disallows tautological predicate names"
diff --git a/src/ameba/rule/style/redundant_begin.cr b/src/ameba/rule/style/redundant_begin.cr
index cb6e56525..3f3009f4b 100644
--- a/src/ameba/rule/style/redundant_begin.cr
+++ b/src/ameba/rule/style/redundant_begin.cr
@@ -55,7 +55,7 @@ module Ameba::Rule::Style
   # Style/RedundantBegin:
   #   Enabled: true
   # ```
-  struct RedundantBegin < Base
+  class RedundantBegin < Base
     include AST::Util
 
     properties do
diff --git a/src/ameba/rule/style/redundant_next.cr b/src/ameba/rule/style/redundant_next.cr
index 15920a60a..5decb7404 100644
--- a/src/ameba/rule/style/redundant_next.cr
+++ b/src/ameba/rule/style/redundant_next.cr
@@ -96,7 +96,7 @@ module Ameba::Rule::Style
   #   AllowMultiNext: true
   #   AllowEmptyNext: true
   # ```
-  struct RedundantNext < Base
+  class RedundantNext < Base
     properties do
       description "Reports redundant next expressions"
 
diff --git a/src/ameba/rule/style/redundant_return.cr b/src/ameba/rule/style/redundant_return.cr
index 3c900283e..e8ec7dc95 100644
--- a/src/ameba/rule/style/redundant_return.cr
+++ b/src/ameba/rule/style/redundant_return.cr
@@ -93,7 +93,7 @@ module Ameba::Rule::Style
   #   AllowMutliReturn: true
   #   AllowEmptyReturn: true
   # ```
-  struct RedundantReturn < Base
+  class RedundantReturn < Base
     properties do
       description "Reports redundant return expressions"
 
diff --git a/src/ameba/rule/style/type_names.cr b/src/ameba/rule/style/type_names.cr
index 8cc8bb0d3..c05699874 100644
--- a/src/ameba/rule/style/type_names.cr
+++ b/src/ameba/rule/style/type_names.cr
@@ -51,7 +51,7 @@ module Ameba::Rule::Style
   # Style/TypeNames:
   #   Enabled: true
   # ```
-  struct TypeNames < Base
+  class TypeNames < Base
     properties do
       description "Enforces type names in camelcase manner"
     end
diff --git a/src/ameba/rule/style/unless_else.cr b/src/ameba/rule/style/unless_else.cr
index 3583c79c3..cdb4b966c 100644
--- a/src/ameba/rule/style/unless_else.cr
+++ b/src/ameba/rule/style/unless_else.cr
@@ -42,7 +42,7 @@ module Ameba::Rule::Style
   # Style/UnlessElse:
   #   Enabled: true
   # ```
-  struct UnlessElse < Base
+  class UnlessElse < Base
     properties do
       description "Disallows the use of an `else` block with the `unless`"
     end
diff --git a/src/ameba/rule/style/variable_names.cr b/src/ameba/rule/style/variable_names.cr
index 3d0efa34f..e8b999c15 100644
--- a/src/ameba/rule/style/variable_names.cr
+++ b/src/ameba/rule/style/variable_names.cr
@@ -22,7 +22,7 @@ module Ameba::Rule::Style
   # Style/VariableNames:
   #   Enabled: true
   # ```
-  struct VariableNames < Base
+  class VariableNames < Base
     properties do
       description "Enforces variable names to be in underscored case"
     end
diff --git a/src/ameba/rule/style/while_true.cr b/src/ameba/rule/style/while_true.cr
index 06e9f1481..4026c2170 100644
--- a/src/ameba/rule/style/while_true.cr
+++ b/src/ameba/rule/style/while_true.cr
@@ -25,7 +25,7 @@ module Ameba::Rule::Style
   # Style/WhileTrue:
   #   Enabled: true
   # ```
-  struct WhileTrue < Base
+  class WhileTrue < Base
     properties do
       description "Disallows while statements with a true literal as condition"
     end

From d3b952f58a73574c7f45604eb4ace773193475e3 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Wed, 20 Jan 2021 03:17:00 +0100
Subject: [PATCH 18/37] Add Performance/ChainedCallsWithNoBang rule

---
 .../chained_calls_with_no_bang_spec.cr        | 69 +++++++++++++++++
 .../performance/chained_calls_with_no_bang.cr | 76 +++++++++++++++++++
 2 files changed, 145 insertions(+)
 create mode 100644 spec/ameba/rule/performance/chained_calls_with_no_bang_spec.cr
 create mode 100644 src/ameba/rule/performance/chained_calls_with_no_bang.cr

diff --git a/spec/ameba/rule/performance/chained_calls_with_no_bang_spec.cr b/spec/ameba/rule/performance/chained_calls_with_no_bang_spec.cr
new file mode 100644
index 000000000..4259b8661
--- /dev/null
+++ b/spec/ameba/rule/performance/chained_calls_with_no_bang_spec.cr
@@ -0,0 +1,69 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Performance
+  subject = ChainedCallsWithNoBang.new
+
+  describe ChainedCallsWithNoBang do
+    it "passes if there is no potential performance improvements" do
+      source = Source.new %(
+        (1..3).select { |e| e > 1 }.sort!
+        (1..3).select { |e| e > 1 }.sort_by!(&.itself)
+        (1..3).select { |e| e > 1 }.uniq!
+        (1..3).select { |e| e > 1 }.shuffle!
+        (1..3).select { |e| e > 1 }.reverse!
+        (1..3).select { |e| e > 1 }.rotate!
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there is select followed by reverse" do
+      source = Source.new %(
+        [1, 2, 3].select { |e| e > 1 }.reverse
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    it "reports if there is select followed by reverse followed by other call" do
+      source = Source.new %(
+        [1, 2, 3].select { |e| e > 2 }.reverse.size
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    context "properties" do
+      it "allows to configure `call_names`" do
+        source = Source.new %(
+          [1, 2, 3].select { |e| e > 2 }.reverse
+        )
+        rule = ChainedCallsWithNoBang.new
+        rule.call_names = %w(uniq)
+        rule.catch(source).should be_valid
+      end
+    end
+
+    it "reports rule, pos and message" do
+      source = Source.new path: "source.cr", code: <<-CODE
+        [1, 2, 3].select { |e| e > 1 }.reverse
+        CODE
+
+      subject.catch(source).should_not be_valid
+      source.issues.size.should eq 1
+
+      issue = source.issues.first
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:1:32"
+      issue.end_location.to_s.should eq "source.cr:1:39"
+
+      issue.message.should eq "Use bang method variant `reverse!` after chained `select` call"
+    end
+
+    context "macro" do
+      it "doesn't report in macro scope" do
+        source = Source.new %(
+          {{ [1, 2, 3].select { |e| e > 2  }.reverse }}
+        )
+        subject.catch(source).should be_valid
+      end
+    end
+  end
+end
diff --git a/src/ameba/rule/performance/chained_calls_with_no_bang.cr b/src/ameba/rule/performance/chained_calls_with_no_bang.cr
new file mode 100644
index 000000000..8e145f7fe
--- /dev/null
+++ b/src/ameba/rule/performance/chained_calls_with_no_bang.cr
@@ -0,0 +1,76 @@
+module Ameba::Rule::Performance
+  # This rule is used to identify usage of chained calls not utilizing
+  # the bang method variants.
+  #
+  # For example, this is considered inefficient:
+  #
+  # ```
+  # names = %w[Alice Bob]
+  # chars = names
+  #   .flat_map(&.chars)
+  #   .uniq
+  #   .sort
+  # ```
+  #
+  # And can be written as this:
+  #
+  # ```
+  # names = %w[Alice Bob]
+  # chars = names
+  #   .flat_map(&.chars)
+  #   .uniq!
+  #   .sort!
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Performance/ChainedCallsWithNoBang
+  #   Enabled: true
+  #   CallNames:
+  #     - uniq
+  #     - sort
+  #     - sort_by
+  #     - shuffle
+  #     - reverse
+  #     - rotate
+  # ```
+  class ChainedCallsWithNoBang < Base
+    properties do
+      description "Identifies usage of chained calls not utilizing the bang method variants."
+
+      # All of those have bang method variants returning `self`
+      # and are not modifying the receiver type (like `compact` does),
+      # thus are safe to switch to the bang variant.
+      call_names : Array(String) = %w(uniq sort sort_by shuffle reverse rotate)
+    end
+
+    # All these methods are allocating a new object
+    ALLOCATING_METHOD_NAMES = %w(
+      keys values values_at map map_with_index flat_map compact_map
+      flatten compact select reject combinations permutations sample
+      transpose invert group_by chunks tally merge chars clone
+      captures named_captures
+    )
+
+    MSG = "Use bang method variant `%s!` after chained `%s` call"
+
+    def test(source)
+      AST::NodeVisitor.new self, source, skip: [
+        Crystal::Macro,
+        Crystal::MacroExpression,
+        Crystal::MacroIf,
+        Crystal::MacroFor,
+      ]
+    end
+
+    def test(source, node : Crystal::Call)
+      return unless (obj = node.obj).is_a?(Crystal::Call)
+      return unless node.name.in?(call_names)
+      return unless obj.name.in?(call_names) || obj.name.in?(ALLOCATING_METHOD_NAMES)
+
+      issue_for node.name_location, node.name_end_location,
+        MSG % {node.name, obj.name}
+    end
+  end
+end

From a219a732585d3bd1c6326b94398c3c9fee6985af Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Fri, 22 Jan 2021 12:20:50 +0100
Subject: [PATCH 19/37] Remove rotate from the list of call_names

In some cases it returns `self` and not a copy.
---
 src/ameba/rule/performance/chained_calls_with_no_bang.cr | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/ameba/rule/performance/chained_calls_with_no_bang.cr b/src/ameba/rule/performance/chained_calls_with_no_bang.cr
index 8e145f7fe..68328dfad 100644
--- a/src/ameba/rule/performance/chained_calls_with_no_bang.cr
+++ b/src/ameba/rule/performance/chained_calls_with_no_bang.cr
@@ -33,7 +33,6 @@ module Ameba::Rule::Performance
   #     - sort_by
   #     - shuffle
   #     - reverse
-  #     - rotate
   # ```
   class ChainedCallsWithNoBang < Base
     properties do
@@ -42,7 +41,7 @@ module Ameba::Rule::Performance
       # All of those have bang method variants returning `self`
       # and are not modifying the receiver type (like `compact` does),
       # thus are safe to switch to the bang variant.
-      call_names : Array(String) = %w(uniq sort sort_by shuffle reverse rotate)
+      call_names : Array(String) = %w(uniq sort sort_by shuffle reverse)
     end
 
     # All these methods are allocating a new object

From 8babeea80fccfb812023995688d538d5dbd5d4c3 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Fri, 22 Jan 2021 12:21:14 +0100
Subject: [PATCH 20/37] Add `repeated_combinations` and `repeated_permutations`

---
 src/ameba/rule/performance/chained_calls_with_no_bang.cr | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/ameba/rule/performance/chained_calls_with_no_bang.cr b/src/ameba/rule/performance/chained_calls_with_no_bang.cr
index 68328dfad..4e0169f6e 100644
--- a/src/ameba/rule/performance/chained_calls_with_no_bang.cr
+++ b/src/ameba/rule/performance/chained_calls_with_no_bang.cr
@@ -47,9 +47,9 @@ module Ameba::Rule::Performance
     # All these methods are allocating a new object
     ALLOCATING_METHOD_NAMES = %w(
       keys values values_at map map_with_index flat_map compact_map
-      flatten compact select reject combinations permutations sample
-      transpose invert group_by chunks tally merge chars clone
-      captures named_captures
+      flatten compact select reject sample group_by chunks tally merge
+      combinations repeated_combinations permutations repeated_permutations
+      transpose invert chars captures named_captures clone
     )
 
     MSG = "Use bang method variant `%s!` after chained `%s` call"

From 6acb8ad2ebd7e22f08571ff3367f122045279f9c Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Fri, 22 Jan 2021 17:24:45 +0100
Subject: [PATCH 21/37] ChainedCallsWithNoBang -> ChainedCallWithNoBang

---
 ...th_no_bang_spec.cr => chained_call_with_no_bang_spec.cr} | 6 +++---
 ...d_calls_with_no_bang.cr => chained_call_with_no_bang.cr} | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)
 rename spec/ameba/rule/performance/{chained_calls_with_no_bang_spec.cr => chained_call_with_no_bang_spec.cr} (94%)
 rename src/ameba/rule/performance/{chained_calls_with_no_bang.cr => chained_call_with_no_bang.cr} (96%)

diff --git a/spec/ameba/rule/performance/chained_calls_with_no_bang_spec.cr b/spec/ameba/rule/performance/chained_call_with_no_bang_spec.cr
similarity index 94%
rename from spec/ameba/rule/performance/chained_calls_with_no_bang_spec.cr
rename to spec/ameba/rule/performance/chained_call_with_no_bang_spec.cr
index 4259b8661..32504ce59 100644
--- a/spec/ameba/rule/performance/chained_calls_with_no_bang_spec.cr
+++ b/spec/ameba/rule/performance/chained_call_with_no_bang_spec.cr
@@ -1,9 +1,9 @@
 require "../../../spec_helper"
 
 module Ameba::Rule::Performance
-  subject = ChainedCallsWithNoBang.new
+  subject = ChainedCallWithNoBang.new
 
-  describe ChainedCallsWithNoBang do
+  describe ChainedCallWithNoBang do
     it "passes if there is no potential performance improvements" do
       source = Source.new %(
         (1..3).select { |e| e > 1 }.sort!
@@ -35,7 +35,7 @@ module Ameba::Rule::Performance
         source = Source.new %(
           [1, 2, 3].select { |e| e > 2 }.reverse
         )
-        rule = ChainedCallsWithNoBang.new
+        rule = ChainedCallWithNoBang.new
         rule.call_names = %w(uniq)
         rule.catch(source).should be_valid
       end
diff --git a/src/ameba/rule/performance/chained_calls_with_no_bang.cr b/src/ameba/rule/performance/chained_call_with_no_bang.cr
similarity index 96%
rename from src/ameba/rule/performance/chained_calls_with_no_bang.cr
rename to src/ameba/rule/performance/chained_call_with_no_bang.cr
index 4e0169f6e..d7f827ae5 100644
--- a/src/ameba/rule/performance/chained_calls_with_no_bang.cr
+++ b/src/ameba/rule/performance/chained_call_with_no_bang.cr
@@ -25,7 +25,7 @@ module Ameba::Rule::Performance
   # YAML configuration example:
   #
   # ```
-  # Performance/ChainedCallsWithNoBang
+  # Performance/ChainedCallWithNoBang
   #   Enabled: true
   #   CallNames:
   #     - uniq
@@ -34,7 +34,7 @@ module Ameba::Rule::Performance
   #     - shuffle
   #     - reverse
   # ```
-  class ChainedCallsWithNoBang < Base
+  class ChainedCallWithNoBang < Base
     properties do
       description "Identifies usage of chained calls not utilizing the bang method variants."
 

From ea98554191bfd5d64a8c52a4271d9af98f9b1160 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Tue, 26 Jan 2021 07:38:19 +0100
Subject: [PATCH 22/37] Add support for showing end location marker (#200)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* Add support for showing end location marker

* Cleanup Reportable method definitions

There’s no need for double splats, since they mess up method resolution, and obscure the actual - single (!) - argument - `status`, so… be gone

Also, all of the helpers return the constructed `Issue` like a behaving good methods.

* Refactor Util#affected_code

* Increase max length of trimmed lines to 120 characters

* Refactor Issue to use enum instead of a symbol for #status

* Optimize Reportable#valid?

* Add spec coverage for newly added Util methods

* Refactor DotFormatter a bit

Make text format moar in line with Crystal spec runner.

* Update README.md
---
 README.md                                  |  10 +-
 spec/ameba/formatter/dot_formatter_spec.cr |  10 +-
 spec/ameba/formatter/util_spec.cr          |  61 +++++++++++-
 spec/ameba/issue_spec.cr                   |  17 +++-
 src/ameba/formatter/dot_formatter.cr       |  23 ++---
 src/ameba/formatter/explain_formatter.cr   |  29 +++---
 src/ameba/formatter/util.cr                | 109 ++++++++++++++-------
 src/ameba/issue.cr                         |  25 +++--
 src/ameba/reportable.cr                    |  43 ++++----
 9 files changed, 226 insertions(+), 101 deletions(-)

diff --git a/README.md b/README.md
index b901259a1..fd5d184ea 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
   <p align="center">Code style linter for Crystal<p>
   <p align="center">
     <sup>
-      <i> (a single-celled animal that catches food and moves about by extending fingerlike projections of protoplasm) </i>
+      <i>(a single-celled animal that catches food and moves about by extending fingerlike projections of protoplasm)</i>
     </sup>
   </p>
   <p align="center">
@@ -35,7 +35,7 @@
 ## About
 
 Ameba is a static code analysis tool for the Crystal language.
-It enforces a consistent [Crystal code style](https://crystal-lang.org/docs/conventions/coding_style.html),
+It enforces a consistent [Crystal code style](https://crystal-lang.org/reference/conventions/coding_style.html),
 also catches code smells and wrong code constructions.
 
 See also [Roadmap](https://github.com/crystal-ameba/ameba/wiki).
@@ -46,7 +46,7 @@ Run `ameba` binary within your project directory to catch code issues:
 
 ```sh
 $ ameba
-Inspecting 107 files.
+Inspecting 107 files
 
 ...............F.....................F....................................................................
 
@@ -61,9 +61,7 @@ src/ameba/formatter/base_formatter.cr:12:7
          ^
 
 Finished in 542.64 milliseconds
-
-129 inspected, 2 failures.
-
+129 inspected, 2 failures
 ```
 
 ### Run in parallel
diff --git a/spec/ameba/formatter/dot_formatter_spec.cr b/spec/ameba/formatter/dot_formatter_spec.cr
index 444426228..3ba909838 100644
--- a/spec/ameba/formatter/dot_formatter_spec.cr
+++ b/spec/ameba/formatter/dot_formatter_spec.cr
@@ -8,7 +8,7 @@ module Ameba::Formatter
     describe "#started" do
       it "writes started message" do
         subject.started [Source.new ""]
-        output.to_s.should eq "Inspecting 1 file.\n\n"
+        output.to_s.should eq "Inspecting 1 file\n\n"
       end
     end
 
@@ -29,7 +29,7 @@ module Ameba::Formatter
     describe "#finished" do
       it "writes a final message" do
         subject.finished [Source.new ""]
-        output.to_s.should contain "1 inspected, 0 failures."
+        output.to_s.should contain "1 inspected, 0 failures"
       end
 
       it "writes the elapsed time" do
@@ -45,7 +45,7 @@ module Ameba::Formatter
           end
           subject.finished [s]
           log = output.to_s
-          log.should contain "1 inspected, 2 failures."
+          log.should contain "1 inspected, 2 failures"
           log.should contain "DummyRuleError"
           log.should contain "NamedRuleError"
         end
@@ -60,7 +60,7 @@ module Ameba::Formatter
           end
           subject.finished [s]
           log = output.to_s
-          log.should contain "> a = 22"
+          log.should contain "> \e[97ma = 22"
           log.should contain "      \e[33m^\e[0m"
         end
 
@@ -99,7 +99,7 @@ module Ameba::Formatter
           s.add_issue(DummyRule.new, location: {1, 1},
             message: "DummyRuleError", status: :disabled)
           subject.finished [s]
-          output.to_s.should contain "1 inspected, 0 failures."
+          output.to_s.should contain "1 inspected, 0 failures"
         end
       end
     end
diff --git a/spec/ameba/formatter/util_spec.cr b/spec/ameba/formatter/util_spec.cr
index 9a002baa7..9087228f5 100644
--- a/spec/ameba/formatter/util_spec.cr
+++ b/spec/ameba/formatter/util_spec.cr
@@ -8,6 +8,65 @@ module Ameba::Formatter
   subject = Subject.new
 
   describe Util do
+    describe "#deansify" do
+      it "returns given string without ANSI codes" do
+        str = String.build do |io|
+          io << "foo".colorize.green.underline
+          io << '-'
+          io << "bar".colorize.red.underline
+        end
+        subject.deansify("foo-bar").should eq "foo-bar"
+        subject.deansify(str).should eq "foo-bar"
+      end
+    end
+
+    describe "#trim" do
+      it "trims string longer than :max_length" do
+        subject.trim(("+" * 300), 1).should eq "+"
+        subject.trim(("+" * 300), 3).should eq "+++"
+        subject.trim(("+" * 300), 5).should eq "+ ..."
+        subject.trim(("+" * 300), 7).should eq "+++ ..."
+      end
+
+      it "leaves intact string shorter than :max_length" do
+        subject.trim(("+" * 3), 100).should eq "+++"
+      end
+
+      it "allows to use custom ellipsis" do
+        subject.trim(("+" * 300), 3, "…").should eq "++…"
+      end
+    end
+
+    describe "#context" do
+      it "returns correct pre/post context lines" do
+        source = Source.new <<-EOF
+          # pre:1
+            # pre:2
+              # pre:3
+                # pre:4
+                  # pre:5
+          a = 1
+                  # post:1
+                # post:2
+              # post:3
+            # post:4
+          # post:5
+          EOF
+
+        subject.context(source.lines, lineno: 6, context_lines: 3)
+          .should eq({<<-PRE.lines, <<-POST.lines
+                # pre:3
+                  # pre:4
+                    # pre:5
+            PRE
+                    # post:1
+                  # post:2
+                # post:3
+            POST
+          })
+      end
+    end
+
     describe "#affected_code" do
       it "returns nil if there is no such a line number" do
         source = Source.new %(
@@ -23,7 +82,7 @@ module Ameba::Formatter
         )
         location = Crystal::Location.new("filename", 1, 1)
         subject.deansify(subject.affected_code(source, location))
-          .should eq "> a = 1\n  ^"
+          .should eq "> a = 1\n  ^\n"
       end
 
       it "returns correct line if it is found" do
diff --git a/spec/ameba/issue_spec.cr b/spec/ameba/issue_spec.cr
index 652f52473..b6488552e 100644
--- a/spec/ameba/issue_spec.cr
+++ b/spec/ameba/issue_spec.cr
@@ -42,9 +42,22 @@ module Ameba
         location: nil,
         end_location: nil,
         message: "",
-        status: :enabled
+        status: :disabled
 
-      issue.status.should eq :enabled
+      issue.status.should eq Issue::Status::Disabled
+      issue.disabled?.should be_true
+      issue.enabled?.should be_false
+    end
+
+    it "sets status to :enabled by default" do
+      issue = Issue.new rule: DummyRule.new,
+        location: nil,
+        end_location: nil,
+        message: ""
+
+      issue.status.should eq Issue::Status::Enabled
+      issue.enabled?.should be_true
+      issue.disabled?.should be_false
     end
   end
 end
diff --git a/src/ameba/formatter/dot_formatter.cr b/src/ameba/formatter/dot_formatter.cr
index d0f43f7a2..121ea1cf3 100644
--- a/src/ameba/formatter/dot_formatter.cr
+++ b/src/ameba/formatter/dot_formatter.cr
@@ -6,14 +6,15 @@ module Ameba::Formatter
   class DotFormatter < BaseFormatter
     include Util
 
-    @started_at : Time?
+    @started_at : Time::Span?
     @mutex = Thread::Mutex.new
 
     # Reports a message when inspection is started.
     def started(sources)
-      @started_at = Time.utc # Time.monotonic
+      @started_at = Time.monotonic
 
-      output << started_message(sources.size)
+      output.puts started_message(sources.size)
+      output.puts
     end
 
     # Reports a result of the inspection of a corresponding source.
@@ -41,29 +42,29 @@ module Ameba::Formatter
             "#{issue.rule.name}: " \
             "#{issue.message}".colorize(:red)
 
-          if show_affected_code && (code = affected_code(source, location))
+          if show_affected_code && (code = affected_code(source, location, issue.end_location))
             output << code.colorize(:default)
           end
 
-          output << '\n'
+          output.puts
         end
       end
 
-      output << finished_in_message(@started_at, Time.utc) # Time.monotonic
-      output << final_message(sources, failed_sources)
+      output.puts finished_in_message(@started_at, Time.monotonic)
+      output.puts final_message(sources, failed_sources)
     end
 
     private def started_message(size)
       if size == 1
-        "Inspecting 1 file.\n\n".colorize(:default)
+        "Inspecting 1 file".colorize(:default)
       else
-        "Inspecting #{size} files.\n\n".colorize(:default)
+        "Inspecting #{size} files".colorize(:default)
       end
     end
 
     private def finished_in_message(started, finished)
       if started && finished
-        "Finished in #{to_human(finished - started)} \n\n".colorize(:default)
+        "Finished in #{to_human(finished - started)}".colorize(:default)
       end
     end
 
@@ -93,7 +94,7 @@ module Ameba::Formatter
       color = failures == 0 ? :green : :red
       s = failures != 1 ? "s" : ""
 
-      "#{total} inspected, #{failures} failure#{s}.\n".colorize(color)
+      "#{total} inspected, #{failures} failure#{s}".colorize(color)
     end
   end
 end
diff --git a/src/ameba/formatter/explain_formatter.cr b/src/ameba/formatter/explain_formatter.cr
index 4724b087d..f8fe87c15 100644
--- a/src/ameba/formatter/explain_formatter.cr
+++ b/src/ameba/formatter/explain_formatter.cr
@@ -20,35 +20,36 @@ module Ameba::Formatter
     # ExplainFormatter.new output,
     #   {file: path, line: line_number, column: column_number}
     # ```
-    def initialize(@output, loc)
-      @location = Crystal::Location.new(loc[:file], loc[:line], loc[:column])
+    def initialize(@output, location)
+      @location = Crystal::Location.new(location[:file], location[:line], location[:column])
     end
 
     # Reports the explainations at the *@location*.
     def finished(sources)
-      source = sources.find { |s| s.path == @location.filename }
-
+      source = sources.find(&.path.==(@location.filename))
       return unless source
 
-      source.issues.each do |issue|
-        if (location = issue.location) &&
-           location.line_number == @location.line_number &&
-           location.column_number == @location.column_number
-          explain(source, issue)
-        end
-      end
+      issue = source.issues.find(&.location.==(@location))
+      return unless issue
+
+      explain(source, issue)
     end
 
     private def explain(source, issue)
       rule = issue.rule
 
+      location, end_location =
+        issue.location, issue.end_location
+
+      return unless location
+
       output_title "ISSUE INFO"
       output_paragraph [
         issue.message.colorize(:red).to_s,
-        @location.to_s.colorize(:cyan).to_s,
+        location.to_s.colorize(:cyan).to_s,
       ]
 
-      if affected_code = affected_code(source, @location, context_lines: 3)
+      if affected_code = affected_code(source, location, end_location, context_lines: 3)
         output_title "AFFECTED CODE"
         output_paragraph affected_code
       end
@@ -68,7 +69,7 @@ module Ameba::Formatter
     end
 
     private def output_paragraph(paragraph : String)
-      output_paragraph(paragraph.split('\n'))
+      output_paragraph(paragraph.lines)
     end
 
     private def output_paragraph(paragraph : Array(String))
diff --git a/src/ameba/formatter/util.cr b/src/ameba/formatter/util.cr
index 822489f06..d6c411c86 100644
--- a/src/ameba/formatter/util.cr
+++ b/src/ameba/formatter/util.cr
@@ -4,70 +4,105 @@ module Ameba::Formatter
       message.try &.gsub(/\x1b[^m]*m/, "").presence
     end
 
-    def affected_code(source, location, context_lines = 0, max_length = 100, placeholder = " ...", prompt = "> ")
+    def trim(str, max_length = 120, ellipsis = " ...")
+      if (str.size - ellipsis.size) > max_length
+        str = str[0, max_length]
+        if str.size > ellipsis.size
+          str = str[0...-ellipsis.size] + ellipsis
+        end
+      end
+      str
+    end
+
+    def context(lines, lineno, context_lines = 3, remove_empty = true)
+      pre_context, post_context = %w[], %w[]
+
+      lines.each_with_index do |line, i|
+        case i + 1
+        when lineno - context_lines...lineno
+          pre_context << line
+        when lineno + 1..lineno + context_lines
+          post_context << line
+        end
+      end
+
+      if remove_empty
+        # remove empty lines at the beginning ...
+        while pre_context.first?.try(&.blank?)
+          pre_context.shift
+        end
+        # ... and the end
+        while post_context.last?.try(&.blank?)
+          post_context.pop
+        end
+      end
+
+      {pre_context, post_context}
+    end
+
+    def affected_code(source, location, end_location = nil, context_lines = 0, max_length = 120, ellipsis = " ...", prompt = "> ")
       lines = source.lines
       lineno, column =
         location.line_number, location.column_number
 
       return unless affected_line = lines[lineno - 1]?.presence
 
-      trim_line = Proc(String, String).new do |line|
-        if line.size > max_length
-          line = line[0, max_length - placeholder.size - 1] + placeholder
-        end
-        line
-      end
-
       if column < max_length
-        affected_line = trim_line.call(affected_line)
+        affected_line = trim(affected_line, max_length, ellipsis)
       end
 
       show_context = context_lines > 0
+
       if show_context
-        pre_context, post_context = %w[], %w[]
-
-        lines.each_with_index do |line, i|
-          case i + 1
-          when lineno - context_lines...lineno
-            pre_context << trim_line.call(line)
-          when lineno
-            #
-          when lineno + 1..lineno + context_lines
-            post_context << trim_line.call(line)
-          end
-        end
+        pre_context, post_context =
+          context(lines, lineno, context_lines)
 
-        # remove empty lines at the beginning/end
-        pre_context.shift? unless pre_context.first?.presence
-        post_context.pop? unless post_context.last?.presence
+        position = prompt.size + column
+        position -= 1
+      else
+        affected_line_size, affected_line =
+          affected_line.size, affected_line.lstrip
+
+        position = column - (affected_line_size - affected_line.size) + prompt.size
+        position -= 1
       end
 
       String.build do |str|
         if show_context
           pre_context.try &.each do |line|
+            line = trim(line, max_length, ellipsis)
             str << prompt
             str.puts(line.colorize(:dark_gray))
           end
+        end
+
+        str << prompt
+        str.puts(affected_line.colorize(:white))
+
+        str << (" " * position)
+        str << "^".colorize(:yellow)
 
-          str << prompt
-          str.puts(affected_line.colorize(:white))
+        if end_location
+          end_lineno = end_location.line_number
+          end_column = end_location.column_number
 
-          str << " " * (prompt.size + column - 1)
-          str.puts("^".colorize(:yellow))
+          if end_lineno == lineno && end_column > column
+            end_position = end_column - column
+            end_position -= 1
 
+            str << ("-" * end_position).colorize(:dark_gray)
+            str << "^".colorize(:yellow)
+          end
+        end
+
+        str.puts
+
+        if show_context
           post_context.try &.each do |line|
+            line = trim(line, max_length, ellipsis)
             str << prompt
             str.puts(line.colorize(:dark_gray))
           end
-        else
-          stripped = affected_line.lstrip
-          position = column - (affected_line.size - stripped.size) + prompt.size
-
-          str << prompt
-          str.puts(stripped)
-
-          str << " " * (position - 1)
-          str << "^".colorize(:yellow)
         end
       end
     end
diff --git a/src/ameba/issue.cr b/src/ameba/issue.cr
index 03e95165b..b913eac3b 100644
--- a/src/ameba/issue.cr
+++ b/src/ameba/issue.cr
@@ -1,22 +1,31 @@
 module Ameba
   # Represents an issue reported by Ameba.
-  record Issue,
+  struct Issue
+    enum Status
+      Enabled
+      Disabled
+    end
+
     # A rule that triggers this issue.
-    rule : Rule::Base,
+    getter rule : Rule::Base
 
     # Location of the issue.
-    location : Crystal::Location?,
+    getter location : Crystal::Location?
 
     # End location of the issue.
-    end_location : Crystal::Location?,
+    getter end_location : Crystal::Location?
 
     # Issue message.
-    message : String,
+    getter message : String
 
     # Issue status.
-    status : Symbol? do
-    def disabled?
-      status == :disabled
+    getter status : Status
+
+    delegate :enabled?, :disabled?,
+      to: status
+
+    def initialize(@rule, @location, @end_location, @message, status : Status? = nil)
+      @status = status || Status::Enabled
     end
 
     def syntax?
diff --git a/src/ameba/reportable.cr b/src/ameba/reportable.cr
index e31ef3a74..4632fa915 100644
--- a/src/ameba/reportable.cr
+++ b/src/ameba/reportable.cr
@@ -5,37 +5,46 @@ module Ameba
     getter issues = [] of Issue
 
     # Adds a new issue to the list of issues.
-    def add_issue(rule, location : Crystal::Location?, end_location : Crystal::Location?, message, status = nil)
-      status ||= :disabled if location_disabled?(location, rule)
-      issues << Issue.new rule, location, end_location, message, status
+    def add_issue(rule, location, end_location, message, status : Issue::Status? = nil) : Issue
+      status ||=
+        Issue::Status::Disabled if location_disabled?(location, rule)
+
+      Issue.new(rule, location, end_location, message, status).tap do |issue|
+        issues << issue
+      end
     end
 
-    # Adds a new issue for AST *node*.
-    def add_issue(rule, node : Crystal::ASTNode, message, **args)
-      add_issue rule, node.location, node.end_location, message, **args
+    # Adds a new issue for Crystal AST *node*.
+    def add_issue(rule, node : Crystal::ASTNode, message, status : Issue::Status? = nil) : Issue
+      add_issue rule, node.location, node.end_location, message, status
     end
 
     # Adds a new issue for Crystal *token*.
-    def add_issue(rule, token : Crystal::Token, message, **args)
-      add_issue rule, token.location, nil, message, **args
+    def add_issue(rule, token : Crystal::Token, message, status : Issue::Status? = nil) : Issue
+      add_issue rule, token.location, nil, message, status
     end
 
     # Adds a new issue for *location* defined by line and column numbers.
-    def add_issue(rule, location : Tuple(Int32, Int32), message, **args)
-      location = Crystal::Location.new path, *location
-      add_issue rule, location, nil, message, **args
+    def add_issue(rule, location : {Int32, Int32}, message, status : Issue::Status? = nil) : Issue
+      location =
+        Crystal::Location.new(path, *location)
+
+      add_issue rule, location, nil, message, status
     end
 
     # Adds a new issue for *location* and *end_location* defined by line and column numbers.
-    def add_issue(rule, location : Tuple(Int32, Int32), end_location : Tuple(Int32, Int32), message, **args)
-      location = Crystal::Location.new path, *location
-      end_location = Crystal::Location.new path, *end_location
-      add_issue rule, location, end_location, message, **args
+    def add_issue(rule, location : {Int32, Int32}, end_location : {Int32, Int32}, message, status : Issue::Status? = nil) : Issue
+      location =
+        Crystal::Location.new(path, *location)
+      end_location =
+        Crystal::Location.new(path, *end_location)
+
+      add_issue rule, location, end_location, message, status
     end
 
-    # Returns true if the list of not disabled issues is empty, false otherwise.
+    # Returns `true` if the list of not disabled issues is empty, `false` otherwise.
     def valid?
-      issues.reject(&.disabled?).empty?
+      issues.none?(&.enabled?)
     end
   end
 end

From 95d340c3ad9aa44b79a7ce3377718f2b25fc95db Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 24 Jan 2021 20:23:32 +0100
Subject: [PATCH 23/37] Add Style/IsAFilter rule

---
 spec/ameba/rule/style/is_a_filter_spec.cr | 64 ++++++++++++++++++++
 src/ameba/rule/style/is_a_filter.cr       | 74 +++++++++++++++++++++++
 2 files changed, 138 insertions(+)
 create mode 100644 spec/ameba/rule/style/is_a_filter_spec.cr
 create mode 100644 src/ameba/rule/style/is_a_filter.cr

diff --git a/spec/ameba/rule/style/is_a_filter_spec.cr b/spec/ameba/rule/style/is_a_filter_spec.cr
new file mode 100644
index 000000000..1a49c2d17
--- /dev/null
+++ b/spec/ameba/rule/style/is_a_filter_spec.cr
@@ -0,0 +1,64 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Style
+  subject = IsAFilter.new
+
+  describe IsAFilter do
+    it "passes if there is no potential performance improvements" do
+      source = Source.new %(
+        [1, 2, nil].select(Int32)
+        [1, 2, nil].reject(Nil)
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there is .is_a? call within select" do
+      source = Source.new %(
+        [1, 2, nil].select(&.is_a?(Int32))
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    it "reports if there is .nil? call within reject" do
+      source = Source.new %(
+        [1, 2, nil].reject(&.nil?)
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    context "properties" do
+      it "allows to configure filter_names" do
+        source = Source.new %(
+          [1, 2, nil].reject(&.nil?)
+        )
+        rule = IsAFilter.new
+        rule.filter_names = %w(select)
+        rule.catch(source).should be_valid
+      end
+    end
+
+    context "macro" do
+      it "reports in macro scope" do
+        source = Source.new %(
+          {{ [1, 2, nil].reject(&.nil?) }}
+        )
+        subject.catch(source).should_not be_valid
+      end
+    end
+
+    it "reports rule, pos and message" do
+      source = Source.new path: "source.cr", code: %(
+        [1, 2, nil].reject(&.nil?)
+      )
+      subject.catch(source).should_not be_valid
+      source.issues.size.should eq 1
+
+      issue = source.issues.first
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:1:13"
+      issue.end_location.to_s.should eq "source.cr:1:26"
+
+      issue.message.should eq "Use `reject(Nil)` instead of `reject {...}`"
+    end
+  end
+end
diff --git a/src/ameba/rule/style/is_a_filter.cr b/src/ameba/rule/style/is_a_filter.cr
new file mode 100644
index 000000000..fedeedeca
--- /dev/null
+++ b/src/ameba/rule/style/is_a_filter.cr
@@ -0,0 +1,74 @@
+module Ameba::Rule::Style
+  # This rule is used to identify usage of `is_a?/nil?` calls within filters.
+  #
+  # For example, this is considered invalid:
+  #
+  # ```
+  # matches = %w[Alice Bob].map(&.match(/^A./))
+  #
+  # matches.any?(&.is_a?(Regex::MatchData)) # => true
+  # matches.one?(&.nil?)                    # => true
+  #
+  # typeof(matches.reject(&.nil?))                    # => Array(Regex::MatchData | Nil)
+  # typeof(matches.select(&.is_a?(Regex::MatchData))) # => Array(Regex::MatchData | Nil)
+  # ```
+  #
+  # And it should be written as this:
+  #
+  # ```
+  # matches = %w[Alice Bob].map(&.match(/^A./))
+  #
+  # matches.any?(Regex::MatchData) # => true
+  # matches.one?(Nil)              # => true
+  #
+  # typeof(matches.reject(Nil))              # => Array(Regex::MatchData)
+  # typeof(matches.select(Regex::MatchData)) # => Array(Regex::MatchData)
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Style/IsAFilter:
+  #   Enabled: true
+  #   FilterNames:
+  #     - select
+  #     - reject
+  #     - any?
+  #     - all?
+  #     - none?
+  #     - one?
+  # ```
+  class IsAFilter < Base
+    properties do
+      description "Identifies usage of `is_a?/nil?` calls within filters."
+      filter_names : Array(String) = %w(select reject any? all? none? one?)
+    end
+
+    MSG = "Use `%s(%s)` instead of `%s {...}`"
+
+    def test(source, node : Crystal::Call)
+      return unless node.name.in?(filter_names)
+      return unless (block = node.block)
+      return unless (body = block.body).is_a?(Crystal::IsA)
+      return unless (path = body.const).is_a?(Crystal::Path)
+      return unless body.obj.is_a?(Crystal::Var)
+
+      name = path.names.join("::")
+      name = "::#{name}" if path.global? && !body.nil_check?
+
+      end_location = node.end_location
+      if !end_location || end_location.try(&.column_number.zero?)
+        if end_location = path.end_location
+          end_location = Crystal::Location.new(
+            end_location.filename,
+            end_location.line_number,
+            end_location.column_number + 1
+          )
+        end
+      end
+
+      issue_for node.name_location, end_location,
+        MSG % {node.name, name, node.name}
+    end
+  end
+end

From d71091a40c1d652cfc1ed22b37b539d0ff1e1065 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Fri, 22 Jan 2021 02:31:18 +0100
Subject: [PATCH 24/37] Add Performance/AnyInsteadOfEmpty rule

---
 .../performance/any_instead_of_empty_spec.cr  | 46 +++++++++++++++++++
 .../rule/performance/any_instead_of_empty.cr  | 44 ++++++++++++++++++
 2 files changed, 90 insertions(+)
 create mode 100644 spec/ameba/rule/performance/any_instead_of_empty_spec.cr
 create mode 100644 src/ameba/rule/performance/any_instead_of_empty.cr

diff --git a/spec/ameba/rule/performance/any_instead_of_empty_spec.cr b/spec/ameba/rule/performance/any_instead_of_empty_spec.cr
new file mode 100644
index 000000000..2a5f82276
--- /dev/null
+++ b/spec/ameba/rule/performance/any_instead_of_empty_spec.cr
@@ -0,0 +1,46 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Performance
+  subject = AnyInsteadOfEmpty.new
+
+  describe AnyInsteadOfEmpty do
+    it "passes if there is no potential performance improvements" do
+      source = Source.new %(
+        [1, 2, 3].any?(&.zero?)
+        [1, 2, 3].any?(String)
+        [1, 2, 3].any?(1..3)
+        [1, 2, 3].any? { |e| e > 1 }
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there is any? call without a block nor argument" do
+      source = Source.new %(
+        [1, 2, 3].any?
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    context "macro" do
+      it "reports in macro scope" do
+        source = Source.new %(
+          {{ [1, 2, 3].any? }}
+        )
+        subject.catch(source).should_not be_valid
+      end
+    end
+
+    it "reports rule, pos and message" do
+      source = Source.new path: "source.cr", code: %(
+        [1, 2, 3].any?
+      )
+      subject.catch(source).should_not be_valid
+      issue = source.issues.first
+
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:1:11"
+      issue.end_location.to_s.should eq "source.cr:1:15"
+      issue.message.should eq "Use `!{...}.empty?` instead of `{...}.any?`"
+    end
+  end
+end
diff --git a/src/ameba/rule/performance/any_instead_of_empty.cr b/src/ameba/rule/performance/any_instead_of_empty.cr
new file mode 100644
index 000000000..6dd7a2bad
--- /dev/null
+++ b/src/ameba/rule/performance/any_instead_of_empty.cr
@@ -0,0 +1,44 @@
+module Ameba::Rule::Performance
+  # This rule is used to identify usage of arg-less `Enumerable#any?` calls.
+  #
+  # Using `Enumerable#any?` instead of `Enumerable#empty?` might lead to an
+  # unexpected results (like `[nil, false].any? # => false`). In some cases
+  # it also might be less efficient, since it iterates until the block will
+  # return a _truthy_ value, instead of just checking if there's at least
+  # one value present.
+  #
+  # For example, this is considered invalid:
+  #
+  # ```
+  # [1, 2, 3].any?
+  # ```
+  #
+  # And it should be written as this:
+  #
+  # ```
+  # ![1, 2, 3].empty?
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Performance/AnyInsteadOfEmpty:
+  #   Enabled: true
+  # ```
+  class AnyInsteadOfEmpty < Base
+    properties do
+      description "Identifies usage of arg-less `any?` calls."
+    end
+
+    ANY_NAME = "any?"
+    MSG      = "Use `!{...}.empty?` instead of `{...}.any?`"
+
+    def test(source, node : Crystal::Call)
+      return unless node.name == ANY_NAME
+      return unless node.block.nil? && node.args.empty?
+      return unless node.obj
+
+      issue_for node.name_location, node.name_end_location, MSG
+    end
+  end
+end

From 7b3c814914052ed023832cdb464757607b7891cb Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Fri, 22 Jan 2021 02:37:11 +0100
Subject: [PATCH 25/37] Fix newly found issues

---
 spec/ameba/ast/scope_spec.cr                          | 2 +-
 spec/ameba/ast/variabling/variable_spec.cr            | 4 ++--
 src/ameba/ast/variabling/variable.cr                  | 2 +-
 src/ameba/ast/visitors/flow_expression_visitor.cr     | 2 +-
 src/ameba/cli/cmd.cr                                  | 2 +-
 src/ameba/rule/lint/unneeded_disable_directive.cr     | 2 +-
 src/ameba/rule/performance/first_last_after_filter.cr | 2 +-
 7 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/spec/ameba/ast/scope_spec.cr b/spec/ameba/ast/scope_spec.cr
index 72951b14d..00f3061cb 100644
--- a/spec/ameba/ast/scope_spec.cr
+++ b/spec/ameba/ast/scope_spec.cr
@@ -51,7 +51,7 @@ module Ameba::AST
     it "adds a new variable to the scope" do
       scope = Scope.new as_node("")
       scope.add_variable(Crystal::Var.new "foo")
-      scope.variables.any?.should be_true
+      scope.variables.empty?.should be_false
     end
   end
 
diff --git a/spec/ameba/ast/variabling/variable_spec.cr b/spec/ameba/ast/variabling/variable_spec.cr
index fc39ef0d1..66b1a1882 100644
--- a/spec/ameba/ast/variabling/variable_spec.cr
+++ b/spec/ameba/ast/variabling/variable_spec.cr
@@ -48,7 +48,7 @@ module Ameba::AST
       it "assigns the variable (creates a new assignment)" do
         variable = Variable.new(var_node, scope)
         variable.assign(assign_node, scope)
-        variable.assignments.any?.should be_true
+        variable.assignments.empty?.should be_false
       end
 
       it "can create multiple assignments" do
@@ -64,7 +64,7 @@ module Ameba::AST
         variable = Variable.new(var_node, scope)
         variable.assign(as_node("foo=1"), scope)
         variable.reference(var_node, scope)
-        variable.references.any?.should be_true
+        variable.references.empty?.should be_false
       end
 
       it "adds a reference to the scope" do
diff --git a/src/ameba/ast/variabling/variable.cr b/src/ameba/ast/variabling/variable.cr
index ea741e820..b3dab3056 100644
--- a/src/ameba/ast/variabling/variable.cr
+++ b/src/ameba/ast/variabling/variable.cr
@@ -58,7 +58,7 @@ module Ameba::AST
     # variable.referenced? # => true
     # ```
     def referenced?
-      references.any?
+      !references.empty?
     end
 
     # Creates a reference to this variable in some scope.
diff --git a/src/ameba/ast/visitors/flow_expression_visitor.cr b/src/ameba/ast/visitors/flow_expression_visitor.cr
index 745927050..69ec1e25f 100644
--- a/src/ameba/ast/visitors/flow_expression_visitor.cr
+++ b/src/ameba/ast/visitors/flow_expression_visitor.cr
@@ -60,7 +60,7 @@ module Ameba::AST
     end
 
     private def in_loop?
-      @loop_stack.any?
+      !@loop_stack.empty?
     end
   end
 end
diff --git a/src/ameba/cli/cmd.cr b/src/ameba/cli/cmd.cr
index 3f80899eb..821f2845c 100644
--- a/src/ameba/cli/cmd.cr
+++ b/src/ameba/cli/cmd.cr
@@ -61,7 +61,7 @@ module Ameba::Cli
         if f.size == 1 && f.first =~ /.+:\d+:\d+/
           configure_explain_opts(f.first, opts)
         else
-          opts.globs = f if f.any?
+          opts.globs = f unless f.empty?
         end
       end
 
diff --git a/src/ameba/rule/lint/unneeded_disable_directive.cr b/src/ameba/rule/lint/unneeded_disable_directive.cr
index d6d8fc2c2..4a55f4463 100644
--- a/src/ameba/rule/lint/unneeded_disable_directive.cr
+++ b/src/ameba/rule/lint/unneeded_disable_directive.cr
@@ -36,7 +36,7 @@ module Ameba::Rule::Lint
         next unless token.type == :COMMENT
         next unless directive = source.parse_inline_directive(token.value.to_s)
         next unless names = unneeded_disables(source, directive, token.location)
-        next unless names.any?
+        next if names.empty?
 
         issue_for token, MSG % names.join(", ")
       end
diff --git a/src/ameba/rule/performance/first_last_after_filter.cr b/src/ameba/rule/performance/first_last_after_filter.cr
index 4333bd6d5..f33680276 100644
--- a/src/ameba/rule/performance/first_last_after_filter.cr
+++ b/src/ameba/rule/performance/first_last_after_filter.cr
@@ -45,7 +45,7 @@ module Ameba::Rule::Performance
     def test(source, node : Crystal::Call)
       return unless node.name.in?(CALL_NAMES) && (obj = node.obj)
       return unless obj.is_a?(Crystal::Call) && obj.block
-      return if !node.block.nil? || node.args.any?
+      return unless node.block.nil? && node.args.empty?
       return unless obj.name.in?(filter_names)
 
       message = node.name.includes?(CALL_NAMES.first) ? MSG : MSG_REVERSE

From ecad80a96b069b4354b8b5ede02011bad4edc859 Mon Sep 17 00:00:00 2001
From: Vitalii Elenhaupt <velenhaupt@gmail.com>
Date: Wed, 3 Feb 2021 09:49:00 +0200
Subject: [PATCH 26/37] NewRule: SpecFocus

closes #172
---
 spec/ameba/rule/lint/spec_focus_spec.cr | 127 ++++++++++++++++++++++++
 src/ameba/rule/lint/spec_focus.cr       |  70 +++++++++++++
 2 files changed, 197 insertions(+)
 create mode 100644 spec/ameba/rule/lint/spec_focus_spec.cr
 create mode 100644 src/ameba/rule/lint/spec_focus.cr

diff --git a/spec/ameba/rule/lint/spec_focus_spec.cr b/spec/ameba/rule/lint/spec_focus_spec.cr
new file mode 100644
index 000000000..328d6f066
--- /dev/null
+++ b/spec/ameba/rule/lint/spec_focus_spec.cr
@@ -0,0 +1,127 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Lint
+  describe SpecFocus do
+    subject = SpecFocus.new
+
+    it "does not report if spec is not focused" do
+      s = Source.new %(
+        context "context" {}
+        describe "describe" {}
+        it "it" {}
+        pending "pending" {}
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should be_valid
+    end
+
+    it "reports if there is a focused context" do
+      s = Source.new %(
+        context "context", focus: true do
+        end
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports if there is a focused describe block" do
+      s = Source.new %(
+        describe "describe", focus: true do
+        end
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports if there is a focused it block" do
+      s = Source.new %(
+        it "it", focus: true do
+        end
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports if there is a focused pending block" do
+      s = Source.new %(
+        pending "pending", focus: true do
+        end
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports if there is a spec item with `focus: false`" do
+      s = Source.new %(
+        it "it", focus: false do
+        end
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should_not be_valid
+    end
+
+    it "does not report if there is non spec block with :focus" do
+      s = Source.new %(
+        some_method "foo", focus: true do
+        end
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should be_valid
+    end
+
+    it "does not report if there is a tagged item with :focus" do
+      s = Source.new %(
+        it "foo", tags: "focus" do
+        end
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should be_valid
+    end
+
+    it "does not report if there are focused spec items without blocks" do
+      s = Source.new %(
+        describe "foo", focus: true
+        context "foo", focus: true
+        it "foo", focus: true
+        pending "foo", focus: true
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should be_valid
+    end
+
+    it "does not report if there are focused items out of spec file" do
+      s = Source.new %(
+        describe "foo", focus: true {}
+        context "foo", focus: true {}
+        it "foo", focus: true {}
+        pending "foo", focus: true {}
+      )
+
+      subject.catch(s).should be_valid
+    end
+
+    it "reports rule, pos and message" do
+      s = Source.new %(
+        it "foo", focus: true do
+          it "bar", focus: true {}
+        end
+      ), path: "source_spec.cr"
+
+      subject.catch(s).should_not be_valid
+
+      s.issues.size.should eq(2)
+
+      first, second = s.issues
+
+      first.rule.should_not be_nil
+      first.location.to_s.should eq "source_spec.cr:1:11"
+      first.end_location.to_s.should eq ""
+      first.message.should eq "Focused spec item detected"
+
+      second.rule.should_not be_nil
+      second.location.to_s.should eq "source_spec.cr:2:13"
+      second.end_location.to_s.should eq ""
+      second.message.should eq "Focused spec item detected"
+    end
+  end
+end
diff --git a/src/ameba/rule/lint/spec_focus.cr b/src/ameba/rule/lint/spec_focus.cr
new file mode 100644
index 000000000..6407fa11e
--- /dev/null
+++ b/src/ameba/rule/lint/spec_focus.cr
@@ -0,0 +1,70 @@
+module Ameba::Rule::Lint
+  # Checks if specs are focused.
+  #
+  # In specs `focus: true` is mainly used to focus on a spec
+  # item locally during development. However, if such change
+  # is committed, it silently runs only focused spec on all
+  # other enviroment, which is undesired.
+  #
+  # This is considered bad:
+  #
+  # ```
+  # describe MyClass, focus: true do
+  # end
+  #
+  # describe ".new", focus: true do
+  # end
+  #
+  # context "my context", focus: true do
+  # end
+  #
+  # it "works", focus: true do
+  # end
+  # ```
+  #
+  # And it should be written as the following:
+  #
+  # ```
+  # describe MyClass do
+  # end
+  #
+  # describe ".new" do
+  # end
+  #
+  # context "my context" do
+  # end
+  #
+  # it "works" do
+  # end
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Lint/SpecFocus:
+  #   Enabled: true
+  # ```
+  class SpecFocus < Base
+    properties do
+      description "Reports focused spec items"
+    end
+
+    MSG             = "Focused spec item detected"
+    SPEC_ITEM_NAMES = %w(describe context it pending)
+
+    def test(source)
+      return unless source.path.ends_with?("_spec.cr")
+
+      AST::NodeVisitor.new self, source
+    end
+
+    def test(source, node : Crystal::Call)
+      return unless node.name.in?(SPEC_ITEM_NAMES)
+      return unless node.block
+
+      arg = node.named_args.try &.find(&.name.== "focus")
+
+      issue_for arg, MSG if arg
+    end
+  end
+end

From f8c22a6e77b839eda99cfe6df1ce5f2803d27e74 Mon Sep 17 00:00:00 2001
From: Vitalii Elenhaupt <velenhaupt@gmail.com>
Date: Wed, 3 Feb 2021 17:14:03 +0200
Subject: [PATCH 27/37] Utilize Source#spec?

---
 spec/ameba/source_spec.cr         | 12 ++++++++++++
 src/ameba/rule/lint/spec_focus.cr |  2 +-
 src/ameba/source.cr               |  7 ++++++-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/spec/ameba/source_spec.cr b/spec/ameba/source_spec.cr
index cd8af8759..fd4781fa4 100644
--- a/spec/ameba/source_spec.cr
+++ b/spec/ameba/source_spec.cr
@@ -23,6 +23,18 @@ module Ameba
       end
     end
 
+    describe "#spec?" do
+      it "returns true if the source is a spec file" do
+        s = Source.new "", "./source_spec.cr"
+        s.spec?.should be_true
+      end
+
+      it "returns false if the source is not a spec file" do
+        s = Source.new "", "./source.cr"
+        s.spec?.should be_false
+      end
+    end
+
     describe "#matches_path?" do
       it "returns true if source's path is matched" do
         s = Source.new "", "source.cr"
diff --git a/src/ameba/rule/lint/spec_focus.cr b/src/ameba/rule/lint/spec_focus.cr
index 6407fa11e..d1810e318 100644
--- a/src/ameba/rule/lint/spec_focus.cr
+++ b/src/ameba/rule/lint/spec_focus.cr
@@ -53,7 +53,7 @@ module Ameba::Rule::Lint
     SPEC_ITEM_NAMES = %w(describe context it pending)
 
     def test(source)
-      return unless source.path.ends_with?("_spec.cr")
+      return unless source.spec?
 
       AST::NodeVisitor.new self, source
     end
diff --git a/src/ameba/source.cr b/src/ameba/source.cr
index 2e3f2af4f..68dd2a1c7 100644
--- a/src/ameba/source.cr
+++ b/src/ameba/source.cr
@@ -53,7 +53,12 @@ module Ameba
       File.expand_path(path)
     end
 
-    # Returns true if *filepath* matches the source's path, false if it does not.
+    # Returns `true` if the source is a spec file, `false` otherwise.
+    def spec?
+      path.ends_with?("_spec.cr")
+    end
+
+    # Returns `true` if *filepath* matches the source's path, `false` if it does not.
     def matches_path?(filepath)
       path == filepath || path == File.expand_path(filepath)
     end

From 0739fad67029def7d55e9f79c8ddcff828478abd Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sun, 24 Jan 2021 20:26:11 +0100
Subject: [PATCH 28/37] Add Style/VerboseBlock rule

---
 spec/ameba/rule/style/verbose_block_spec.cr | 131 +++++++++++++++++
 src/ameba/rule/style/verbose_block.cr       | 150 ++++++++++++++++++++
 2 files changed, 281 insertions(+)
 create mode 100644 spec/ameba/rule/style/verbose_block_spec.cr
 create mode 100644 src/ameba/rule/style/verbose_block.cr

diff --git a/spec/ameba/rule/style/verbose_block_spec.cr b/spec/ameba/rule/style/verbose_block_spec.cr
new file mode 100644
index 000000000..bca8cf031
--- /dev/null
+++ b/spec/ameba/rule/style/verbose_block_spec.cr
@@ -0,0 +1,131 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Style
+  subject = VerboseBlock.new
+
+  describe VerboseBlock do
+    it "passes if there is no potential performance improvements" do
+      source = Source.new %(
+        (1..3).any?(&.odd?)
+        (1..3).join('.', &.to_s)
+        (1..3).map { |i| typeof(i) }
+        (1..3).map { |i| i || 0 }
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there is a call with a collapsible block" do
+      source = Source.new %(
+        (1..3).any? { |i| i.odd? }
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    it "reports if there is a call with an argument + collapsible block" do
+      source = Source.new %(
+        (1..3).join('.') { |i| i.to_s }
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    it "reports if there is a call with a collapsible block (with chained call)" do
+      source = Source.new %(
+        (1..3).map { |i| i.to_s.split.reverse.join.strip }
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    context "properties" do
+      it "#exclude_calls_with_block" do
+        source = Source.new %(
+          (1..3).in_groups_of(1) { |i| i.map(&.to_s) }
+        )
+        rule = VerboseBlock.new
+        rule
+          .tap(&.exclude_calls_with_block = true)
+          .catch(source).should be_valid
+        rule
+          .tap(&.exclude_calls_with_block = false)
+          .catch(source).should_not be_valid
+      end
+
+      it "#exclude_multiple_line_blocks" do
+        source = Source.new %(
+          (1..3).any? do |i|
+            i.odd?
+          end
+        )
+        rule = VerboseBlock.new
+        rule
+          .tap(&.exclude_multiple_line_blocks = true)
+          .catch(source).should be_valid
+        rule
+          .tap(&.exclude_multiple_line_blocks = false)
+          .catch(source).should_not be_valid
+      end
+
+      it "#exclude_operators" do
+        source = Source.new %(
+          (1..3).sum { |i| i * 2 }
+        )
+        rule = VerboseBlock.new
+        rule
+          .tap(&.exclude_operators = true)
+          .catch(source).should be_valid
+        rule
+          .tap(&.exclude_operators = false)
+          .catch(source).should_not be_valid
+      end
+
+      it "#exclude_setters" do
+        source = Source.new %(
+          Char::Reader.new("abc").tap { |reader| reader.pos = 0 }
+        )
+        rule = VerboseBlock.new
+        rule
+          .tap(&.exclude_setters = true)
+          .catch(source).should be_valid
+        rule
+          .tap(&.exclude_setters = false)
+          .catch(source).should_not be_valid
+      end
+
+      it "#max_length" do
+        source = Source.new %(
+          (1..3).tap { |i| i.to_s.split.reverse.join.strip.blank? }
+        )
+        rule = VerboseBlock.new
+        rule
+          .tap(&.max_length = 30)
+          .catch(source).should be_valid
+        rule
+          .tap(&.max_length = nil)
+          .catch(source).should_not be_valid
+      end
+    end
+
+    context "macro" do
+      it "reports in macro scope" do
+        source = Source.new %(
+          {{ (1..3).any? { |i| i.odd? } }}
+        )
+        subject.catch(source).should_not be_valid
+      end
+    end
+
+    it "reports rule, pos and message" do
+      source = Source.new path: "source.cr", code: %(
+        (1..3).any? { |i| i.odd? }
+      )
+      subject.catch(source).should_not be_valid
+      source.issues.size.should eq 1
+
+      issue = source.issues.first
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:1:8"
+      issue.end_location.to_s.should eq "source.cr:1:26"
+
+      issue.message.should eq "Use short block notation instead: `any?(&.odd?)`"
+    end
+  end
+end
diff --git a/src/ameba/rule/style/verbose_block.cr b/src/ameba/rule/style/verbose_block.cr
new file mode 100644
index 000000000..f36728f26
--- /dev/null
+++ b/src/ameba/rule/style/verbose_block.cr
@@ -0,0 +1,150 @@
+module Ameba::Rule::Style
+  # This rule is used to identify usage of single expression blocks with
+  # argument as a receiver, that can be collapsed into a short form.
+  #
+  # For example, this is considered invalid:
+  #
+  # ```
+  # (1..3).any? { |i| i.odd? }
+  # ```
+  #
+  # And it should be written as this:
+  #
+  # ```
+  # (1..3).any?(&.odd?)
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Style/VerboseBlock:
+  #   Enabled: true
+  #   ExcludeMultipleLineBlocks: true
+  #   ExcludeCallsWithBlocks: false
+  #   ExcludeOperators: false
+  #   ExcludeSetters: false
+  #   MaxLength: 50 # use ~ to disable
+  # ```
+  class VerboseBlock < Base
+    properties do
+      description "Identifies usage of collapsible single expression blocks."
+
+      exclude_calls_with_block true
+      exclude_multiple_line_blocks false
+      exclude_operators false
+      exclude_setters false
+
+      max_length : Int32? = 50
+    end
+
+    MSG          = "Use short block notation instead: `%s`"
+    CALL_PATTERN = "%s(%s&.%s)"
+
+    protected def same_location_lines?(a, b)
+      return unless a_location = a.name_location
+      return unless b_location = b.location
+
+      a_location.line_number == b_location.line_number
+    end
+
+    private OPERATOR_CHARS =
+      {'[', ']', '!', '=', '>', '<', '~', '+', '-', '*', '/', '%', '^', '|', '&'}
+
+    protected def operator?(name)
+      name.each_char do |char|
+        return false unless char.in?(OPERATOR_CHARS)
+      end
+      !name.empty?
+    end
+
+    protected def setter?(name)
+      !name.empty? && name[0].letter? && name.ends_with?('=')
+    end
+
+    protected def valid_length?(code)
+      if max_length = self.max_length
+        return code.size <= max_length
+      end
+      true
+    end
+
+    protected def node_to_s(node : Crystal::Call)
+      case name = node.name
+      when "[]"
+        name = "[#{node.args.join ", "}]"
+      when "[]?"
+        name = "[#{node.args.join ", "}]?"
+      when "[]="
+        unless node.args.empty?
+          name = "[#{node.args[..-2].join ", "}]=(#{node.args.last})"
+        end
+      else
+        name += "(#{node.args.join ", "})" unless node.args.empty?
+        name += " {...}" if node.block
+      end
+      name
+    end
+
+    protected def call_code(call, body)
+      args = call.args.join ", " unless call.args.empty?
+      args += ", " if args
+
+      call_chain = %w[].tap do |arr|
+        obj = body.obj
+        while obj.is_a?(Crystal::Call)
+          arr << node_to_s(obj)
+          obj = obj.obj
+        end
+        arr.reverse!
+        arr << node_to_s(body)
+      end
+
+      name =
+        call_chain.join('.')
+
+      CALL_PATTERN % {call.name, args, name}
+    end
+
+    # ameba:disable Metrics/CyclomaticComplexity
+    def test(source, node : Crystal::Call)
+      # we are interested only in calls with block taking a single argument
+      #
+      # ```
+      # (1..3).any? { |i| i.to_i64.odd? }
+      #        ^---    ^  ^------------
+      #        block  arg  body
+      # ```
+      return unless (block = node.block) && block.args.size == 1
+
+      # we filter out the blocks that are of call type - `i.to_i64.odd?`
+      return unless (body = block.body).is_a?(Crystal::Call)
+
+      # we need to "unwind" the chain challs, so the final receiver object
+      # ends up being a variable - `i`
+      obj = body.obj
+      while obj.is_a?(Crystal::Call)
+        obj = obj.obj
+      end
+      return unless obj.is_a?(Crystal::Var)
+
+      # only calls with a first argument used as a receiver are the valid game
+      return unless (arg = block.args.first) == obj
+
+      # we skip auto-generated blocks - `(1..3).any?(&.odd?)`
+      return if arg.name.starts_with?("__arg")
+
+      return if exclude_calls_with_block && body.block
+      return if exclude_multiple_line_blocks && !same_location_lines?(node, body)
+      return if exclude_operators && operator?(body.name)
+      return if exclude_setters && setter?(body.name)
+
+      call_code =
+        call_code(node, body)
+
+      return unless valid_length?(call_code)
+
+      issue_for node.name_location, node.end_location,
+        MSG % call_code
+    end
+  end
+end

From a53d44617d681906c69928c1cc9a383177d1cf1e Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Mon, 25 Jan 2021 02:34:33 +0100
Subject: [PATCH 29/37] Fix newly found issues

---
 spec/ameba/config_spec.cr   | 4 ++--
 spec/ameba/severity_spec.cr | 4 +---
 src/ameba/ast/scope.cr      | 2 +-
 src/ameba/glob_utils.cr     | 2 +-
 src/ameba/runner.cr         | 2 +-
 5 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/spec/ameba/config_spec.cr b/spec/ameba/config_spec.cr
index c92768737..d7547a2a9 100644
--- a/spec/ameba/config_spec.cr
+++ b/spec/ameba/config_spec.cr
@@ -120,7 +120,7 @@ module Ameba
       it "returns list of sources" do
         config.sources.size.should be > 0
         config.sources.first.should be_a Source
-        config.sources.any? { |s| s.fullpath == __FILE__ }.should be_true
+        config.sources.any?(&.fullpath.==(__FILE__)).should be_true
       end
 
       it "returns a list of sources mathing globs" do
@@ -130,7 +130,7 @@ module Ameba
 
       it "returns a lisf of sources excluding 'Excluded'" do
         config.excluded = %w(**/config_spec.cr)
-        config.sources.any? { |s| s.fullpath == __FILE__ }.should be_false
+        config.sources.any?(&.fullpath.==(__FILE__)).should be_false
       end
     end
 
diff --git a/spec/ameba/severity_spec.cr b/spec/ameba/severity_spec.cr
index 94f3b7304..cf63c1334 100644
--- a/spec/ameba/severity_spec.cr
+++ b/spec/ameba/severity_spec.cr
@@ -4,9 +4,7 @@ module Ameba
   describe Severity do
     describe "#symbol" do
       it "returns the symbol for each severity in the enum" do
-        Severity.values.each do |severity|
-          severity.symbol.should_not be_nil
-        end
+        Severity.values.each(&.symbol.should_not(be_nil))
       end
 
       it "returns symbol for Error" do
diff --git a/src/ameba/ast/scope.cr b/src/ameba/ast/scope.cr
index 68bed1563..bacf42585 100644
--- a/src/ameba/ast/scope.cr
+++ b/src/ameba/ast/scope.cr
@@ -78,7 +78,7 @@ module Ameba::AST
     # scope.find_variable("foo")
     # ```
     def find_variable(name : String)
-      variables.find { |v| v.name == name } || outer_scope.try &.find_variable(name)
+      variables.find(&.name.==(name)) || outer_scope.try &.find_variable(name)
     end
 
     # Creates a new assignment for the variable.
diff --git a/src/ameba/glob_utils.cr b/src/ameba/glob_utils.cr
index a4a035495..71cd0cb5f 100644
--- a/src/ameba/glob_utils.cr
+++ b/src/ameba/glob_utils.cr
@@ -11,7 +11,7 @@ module Ameba
       rejected = rejected_globs(globs)
       selected = globs - rejected
 
-      expand(selected) - expand(rejected.map! { |p| p[1..-1] })
+      expand(selected) - expand(rejected.map!(&.[1..-1]))
     end
 
     # Expands globs. Globs can point to files or even directories.
diff --git a/src/ameba/runner.cr b/src/ameba/runner.cr
index 9e6d29657..56b06e644 100644
--- a/src/ameba/runner.cr
+++ b/src/ameba/runner.cr
@@ -126,7 +126,7 @@ module Ameba
       @sources.all? do |source|
         source.issues
           .reject(&.disabled?)
-          .none? { |issue| issue.rule.severity <= @severity }
+          .none?(&.rule.severity.<=(@severity))
       end
     end
 

From 4b7f3ba6ee5ba425bef6987080b4bb3327019d9e Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Sat, 30 Jan 2021 18:22:10 +0100
Subject: [PATCH 30/37] Add MaxLineLength option to Style/VerboseBlock rule

---
 spec/ameba/rule/style/verbose_block_spec.cr | 15 +++++++++++++++
 src/ameba/rule/style/verbose_block.cr       | 13 +++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/spec/ameba/rule/style/verbose_block_spec.cr b/spec/ameba/rule/style/verbose_block_spec.cr
index bca8cf031..60e5f676b 100644
--- a/spec/ameba/rule/style/verbose_block_spec.cr
+++ b/spec/ameba/rule/style/verbose_block_spec.cr
@@ -90,6 +90,21 @@ module Ameba::Rule::Style
           .catch(source).should_not be_valid
       end
 
+      it "#max_line_length" do
+        source = Source.new %(
+          (1..3).tap &.tap &.tap &.tap &.tap &.tap &.tap do |i|
+            i.to_s.reverse.strip.blank?
+          end
+        )
+        rule = VerboseBlock.new
+        rule
+          .tap(&.max_line_length = 60)
+          .catch(source).should be_valid
+        rule
+          .tap(&.max_line_length = nil)
+          .catch(source).should_not be_valid
+      end
+
       it "#max_length" do
         source = Source.new %(
           (1..3).tap { |i| i.to_s.split.reverse.join.strip.blank? }
diff --git a/src/ameba/rule/style/verbose_block.cr b/src/ameba/rule/style/verbose_block.cr
index f36728f26..5a09f372b 100644
--- a/src/ameba/rule/style/verbose_block.cr
+++ b/src/ameba/rule/style/verbose_block.cr
@@ -23,6 +23,7 @@ module Ameba::Rule::Style
   #   ExcludeCallsWithBlocks: false
   #   ExcludeOperators: false
   #   ExcludeSetters: false
+  #   MaxLineLength: ~
   #   MaxLength: 50 # use ~ to disable
   # ```
   class VerboseBlock < Base
@@ -34,6 +35,7 @@ module Ameba::Rule::Style
       exclude_operators false
       exclude_setters false
 
+      max_line_length : Int32? = nil # 100
       max_length : Int32? = 50
     end
 
@@ -68,6 +70,16 @@ module Ameba::Rule::Style
       true
     end
 
+    protected def valid_line_length?(node, code)
+      if max_line_length = self.max_line_length
+        if location = node.name_location
+          final_line_length = location.column_number + code.size
+          return final_line_length <= max_line_length
+        end
+      end
+      true
+    end
+
     protected def node_to_s(node : Crystal::Call)
       case name = node.name
       when "[]"
@@ -141,6 +153,7 @@ module Ameba::Rule::Style
       call_code =
         call_code(node, body)
 
+      return unless valid_line_length?(node, call_code)
       return unless valid_length?(call_code)
 
       issue_for node.name_location, node.end_location,

From 5faf8da81cac3b2e1d0112fa4488bf1a1fa1721a Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Mon, 1 Feb 2021 01:51:21 +0100
Subject: [PATCH 31/37] Split VerboseBlock#test method into a smaller pieces

---
 src/ameba/rule/style/verbose_block.cr | 32 +++++++++++++++------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/src/ameba/rule/style/verbose_block.cr b/src/ameba/rule/style/verbose_block.cr
index 5a09f372b..552bdb777 100644
--- a/src/ameba/rule/style/verbose_block.cr
+++ b/src/ameba/rule/style/verbose_block.cr
@@ -117,7 +117,22 @@ module Ameba::Rule::Style
       CALL_PATTERN % {call.name, args, name}
     end
 
-    # ameba:disable Metrics/CyclomaticComplexity
+    protected def issue_for_valid(source, call : Crystal::Call, body : Crystal::Call)
+      return if exclude_calls_with_block && body.block
+      return if exclude_multiple_line_blocks && !same_location_lines?(call, body)
+      return if exclude_operators && operator?(body.name)
+      return if exclude_setters && setter?(body.name)
+
+      call_code =
+        call_code(call, body)
+
+      return unless valid_line_length?(call, call_code)
+      return unless valid_length?(call_code)
+
+      issue_for call.name_location, call.end_location,
+        MSG % call_code
+    end
+
     def test(source, node : Crystal::Call)
       # we are interested only in calls with block taking a single argument
       #
@@ -145,19 +160,8 @@ module Ameba::Rule::Style
       # we skip auto-generated blocks - `(1..3).any?(&.odd?)`
       return if arg.name.starts_with?("__arg")
 
-      return if exclude_calls_with_block && body.block
-      return if exclude_multiple_line_blocks && !same_location_lines?(node, body)
-      return if exclude_operators && operator?(body.name)
-      return if exclude_setters && setter?(body.name)
-
-      call_code =
-        call_code(node, body)
-
-      return unless valid_line_length?(node, call_code)
-      return unless valid_length?(call_code)
-
-      issue_for node.name_location, node.end_location,
-        MSG % call_code
+      # add issue if the given nodes pass all of the checks
+      issue_for_valid source, node, body
     end
   end
 end

From eed094b928f0f2a944c96664b8019642c4f4a6d0 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Tue, 2 Feb 2021 13:52:03 +0100
Subject: [PATCH 32/37] Fix couple of edge-cases in VerboseBlock rule

---
 spec/ameba/rule/style/verbose_block_spec.cr | 12 ++++++++
 src/ameba/rule/style/verbose_block.cr       | 32 +++++++++++++++++++--
 2 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/spec/ameba/rule/style/verbose_block_spec.cr b/spec/ameba/rule/style/verbose_block_spec.cr
index 60e5f676b..3122eb972 100644
--- a/spec/ameba/rule/style/verbose_block_spec.cr
+++ b/spec/ameba/rule/style/verbose_block_spec.cr
@@ -14,6 +14,18 @@ module Ameba::Rule::Style
       subject.catch(source).should be_valid
     end
 
+    it "passes if the block argument is used within the body" do
+      source = Source.new %(
+        (1..3).map { |i| i * i }
+        (1..3).map { |j| j * j.to_i64 }
+        (1..3).map { |k| k.to_i64 * k }
+        (1..3).map { |l| l.to_i64 * l.to_i64 }
+        (1..3).map { |m| m.to_s[start: m.to_i64, count: 3]? }
+        (1..3).map { |n| n.to_s.split.map { |z| n.to_i * z.to_i }.join }
+      )
+      subject.catch(source).should be_valid
+    end
+
     it "reports if there is a call with a collapsible block" do
       source = Source.new %(
         (1..3).any? { |i| i.odd? }
diff --git a/src/ameba/rule/style/verbose_block.cr b/src/ameba/rule/style/verbose_block.cr
index 552bdb777..42784f4d3 100644
--- a/src/ameba/rule/style/verbose_block.cr
+++ b/src/ameba/rule/style/verbose_block.cr
@@ -80,6 +80,27 @@ module Ameba::Rule::Style
       true
     end
 
+    protected def reference_count(node, obj : Crystal::Var)
+      i = 0
+      case node
+      when Crystal::Call
+        i += reference_count(node.obj, obj)
+        i += reference_count(node.block, obj)
+
+        node.args.each do |arg|
+          i += reference_count(arg, obj)
+        end
+        node.named_args.try &.each do |arg|
+          i += reference_count(arg.value, obj)
+        end
+      when Crystal::Block
+        i += reference_count(node.body, obj)
+      when Crystal::Var
+        i += 1 if node == obj
+      end
+      i
+    end
+
     protected def node_to_s(node : Crystal::Call)
       case name = node.name
       when "[]"
@@ -143,6 +164,11 @@ module Ameba::Rule::Style
       # ```
       return unless (block = node.block) && block.args.size == 1
 
+      arg = block.args.first
+
+      # we skip auto-generated blocks - `(1..3).any?(&.odd?)`
+      return if arg.name.starts_with?("__arg")
+
       # we filter out the blocks that are of call type - `i.to_i64.odd?`
       return unless (body = block.body).is_a?(Crystal::Call)
 
@@ -155,10 +181,10 @@ module Ameba::Rule::Style
       return unless obj.is_a?(Crystal::Var)
 
       # only calls with a first argument used as a receiver are the valid game
-      return unless (arg = block.args.first) == obj
+      return unless obj == arg
 
-      # we skip auto-generated blocks - `(1..3).any?(&.odd?)`
-      return if arg.name.starts_with?("__arg")
+      # we bail out if the block node include the block argument
+      return if reference_count(body, arg) > 1
 
       # add issue if the given nodes pass all of the checks
       issue_for_valid source, node, body

From 16743a756cf329f7d6610d8e7d40838c00948dba Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Wed, 3 Feb 2021 02:00:49 +0100
Subject: [PATCH 33/37] Add ExcludePrefixOperators option to Style/VerboseBlock
 rule

---
 spec/ameba/rule/style/verbose_block_spec.cr | 14 ++++++++++++++
 src/ameba/rule/style/verbose_block.cr       | 11 ++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/spec/ameba/rule/style/verbose_block_spec.cr b/spec/ameba/rule/style/verbose_block_spec.cr
index 3122eb972..b53aa6927 100644
--- a/spec/ameba/rule/style/verbose_block_spec.cr
+++ b/spec/ameba/rule/style/verbose_block_spec.cr
@@ -76,6 +76,20 @@ module Ameba::Rule::Style
           .catch(source).should_not be_valid
       end
 
+      it "#exclude_prefix_operators" do
+        source = Source.new %(
+          (1..3).sum { |i| +i }
+          (1..3).sum { |i| -i }
+        )
+        rule = VerboseBlock.new
+        rule
+          .tap(&.exclude_prefix_operators = true)
+          .catch(source).should be_valid
+        rule
+          .tap(&.exclude_prefix_operators = false)
+          .catch(source).should_not be_valid
+      end
+
       it "#exclude_operators" do
         source = Source.new %(
           (1..3).sum { |i| i * 2 }
diff --git a/src/ameba/rule/style/verbose_block.cr b/src/ameba/rule/style/verbose_block.cr
index 42784f4d3..a3ec6142d 100644
--- a/src/ameba/rule/style/verbose_block.cr
+++ b/src/ameba/rule/style/verbose_block.cr
@@ -21,6 +21,7 @@ module Ameba::Rule::Style
   #   Enabled: true
   #   ExcludeMultipleLineBlocks: true
   #   ExcludeCallsWithBlocks: false
+  #   ExcludePrefixOperators: true
   #   ExcludeOperators: false
   #   ExcludeSetters: false
   #   MaxLineLength: ~
@@ -32,6 +33,7 @@ module Ameba::Rule::Style
 
       exclude_calls_with_block true
       exclude_multiple_line_blocks false
+      exclude_prefix_operators true
       exclude_operators false
       exclude_setters false
 
@@ -49,9 +51,14 @@ module Ameba::Rule::Style
       a_location.line_number == b_location.line_number
     end
 
-    private OPERATOR_CHARS =
+    private PREFIX_OPERATORS = {"+", "-"}
+    private OPERATOR_CHARS   =
       {'[', ']', '!', '=', '>', '<', '~', '+', '-', '*', '/', '%', '^', '|', '&'}
 
+    protected def prefix_operator?(node)
+      node.name.in?(PREFIX_OPERATORS) && node.args.empty?
+    end
+
     protected def operator?(name)
       name.each_char do |char|
         return false unless char.in?(OPERATOR_CHARS)
@@ -138,9 +145,11 @@ module Ameba::Rule::Style
       CALL_PATTERN % {call.name, args, name}
     end
 
+    # ameba:disable Metrics/CyclomaticComplexity
     protected def issue_for_valid(source, call : Crystal::Call, body : Crystal::Call)
       return if exclude_calls_with_block && body.block
       return if exclude_multiple_line_blocks && !same_location_lines?(call, body)
+      return if exclude_prefix_operators && prefix_operator?(body)
       return if exclude_operators && operator?(body.name)
       return if exclude_setters && setter?(body.name)
 

From a9d1b17debf34eb716089bc3cc0d9146408df70a Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Wed, 3 Feb 2021 13:39:35 +0100
Subject: [PATCH 34/37] Support named arguments in VerboseBlock#node_to_s

---
 spec/ameba/rule/style/verbose_block_spec.cr | 38 ++++++++++++++++
 src/ameba/rule/style/verbose_block.cr       | 49 +++++++++++++++------
 2 files changed, 74 insertions(+), 13 deletions(-)

diff --git a/spec/ameba/rule/style/verbose_block_spec.cr b/spec/ameba/rule/style/verbose_block_spec.cr
index b53aa6927..3a6ff8fe1 100644
--- a/spec/ameba/rule/style/verbose_block_spec.cr
+++ b/spec/ameba/rule/style/verbose_block_spec.cr
@@ -154,6 +154,44 @@ module Ameba::Rule::Style
       end
     end
 
+    it "reports call args and named_args" do
+      short_block_variants = {
+        %|map(&.to_s.[start: 0.to_i64, count: 3]?)|,
+        %|map(&.to_s.[0.to_i64, count: 3]?)|,
+        %|map(&.to_s.[0.to_i64, 3]?)|,
+        %|map(&.to_s.[start: 0.to_i64, count: 3]=("foo"))|,
+        %|map(&.to_s.[0.to_i64, count: 3]=("foo"))|,
+        %|map(&.to_s.[0.to_i64, 3]=("foo"))|,
+        %|map(&.to_s.camelcase(lower: true))|,
+        %|map(&.to_s.camelcase)|,
+        %|map(&.to_s.gsub('_', '-'))|,
+        %|map(&.in?(*{1, 2, 3}, **{foo: :bar}))|,
+        %|map(&.in?(1, *foo, 3, **bar))|,
+        %|join(separator: '.', &.to_s)|,
+      }
+
+      source = Source.new path: "source.cr", code: %(
+        (1..3).map { |i| i.to_s[start: 0.to_i64, count: 3]? }
+        (1..3).map { |i| i.to_s[0.to_i64, count: 3]? }
+        (1..3).map { |i| i.to_s[0.to_i64, 3]? }
+        (1..3).map { |i| i.to_s[start: 0.to_i64, count: 3] = "foo" }
+        (1..3).map { |i| i.to_s[0.to_i64, count: 3] = "foo" }
+        (1..3).map { |i| i.to_s[0.to_i64, 3] = "foo" }
+        (1..3).map { |i| i.to_s.camelcase(lower: true) }
+        (1..3).map { |i| i.to_s.camelcase }
+        (1..3).map { |i| i.to_s.gsub('_', '-') }
+        (1..3).map { |i| i.in?(*{1, 2, 3}, **{foo: :bar}) }
+        (1..3).map { |i| i.in?(1, *foo, 3, **bar) }
+        (1..3).join(separator: '.') { |i| i.to_s }
+      )
+      subject.catch(source).should_not be_valid
+      source.issues.size.should eq(short_block_variants.size)
+
+      source.issues.each_with_index do |issue, i|
+        issue.message.should eq(VerboseBlock::MSG % short_block_variants[i])
+      end
+    end
+
     it "reports rule, pos and message" do
       source = Source.new path: "source.cr", code: %(
         (1..3).any? { |i| i.odd? }
diff --git a/src/ameba/rule/style/verbose_block.cr b/src/ameba/rule/style/verbose_block.cr
index a3ec6142d..12bb0e0ba 100644
--- a/src/ameba/rule/style/verbose_block.cr
+++ b/src/ameba/rule/style/verbose_block.cr
@@ -108,25 +108,48 @@ module Ameba::Rule::Style
       i
     end
 
+    protected def args_to_s(io : IO, node : Crystal::Call, skip_last_arg = false)
+      node.args.dup.tap do |args|
+        args.pop? if skip_last_arg
+        args.join io, ", "
+        node.named_args.try do |named_args|
+          io << ", " unless args.empty? || named_args.empty?
+          named_args.join io, ", " do |arg, inner_io|
+            inner_io << arg.name << ": " << arg.value
+          end
+        end
+      end
+    end
+
     protected def node_to_s(node : Crystal::Call)
-      case name = node.name
-      when "[]"
-        name = "[#{node.args.join ", "}]"
-      when "[]?"
-        name = "[#{node.args.join ", "}]?"
-      when "[]="
-        unless node.args.empty?
-          name = "[#{node.args[..-2].join ", "}]=(#{node.args.last})"
+      String.build do |str|
+        case name = node.name
+        when "[]"
+          str << '['
+          args_to_s(str, node)
+          str << ']'
+        when "[]?"
+          str << '['
+          args_to_s(str, node)
+          str << "]?"
+        when "[]="
+          str << '['
+          args_to_s(str, node, skip_last_arg: true)
+          str << "]=(" << node.args.last? << ')'
+        else
+          str << name
+          if !node.args.empty? || (node.named_args && !node.named_args.try(&.empty?))
+            str << '('
+            args_to_s(str, node)
+            str << ')'
+          end
+          str << " {...}" if node.block
         end
-      else
-        name += "(#{node.args.join ", "})" unless node.args.empty?
-        name += " {...}" if node.block
       end
-      name
     end
 
     protected def call_code(call, body)
-      args = call.args.join ", " unless call.args.empty?
+      args = String.build { |io| args_to_s(io, call) }.presence
       args += ", " if args
 
       call_chain = %w[].tap do |arr|

From 694c41650c92fbbb298f4f34ecaee7e7709b98e7 Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Thu, 4 Feb 2021 22:24:29 +0100
Subject: [PATCH 35/37] Remove redundant check and add a few more test cases

---
 spec/ameba/rule/style/verbose_block_spec.cr | 4 ++++
 src/ameba/rule/style/verbose_block.cr       | 1 -
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/spec/ameba/rule/style/verbose_block_spec.cr b/spec/ameba/rule/style/verbose_block_spec.cr
index 3a6ff8fe1..3689cecb9 100644
--- a/spec/ameba/rule/style/verbose_block_spec.cr
+++ b/spec/ameba/rule/style/verbose_block_spec.cr
@@ -8,8 +8,12 @@ module Ameba::Rule::Style
       source = Source.new %(
         (1..3).any?(&.odd?)
         (1..3).join('.', &.to_s)
+        (1..3).each_with_index { |i, idx| i * idx }
         (1..3).map { |i| typeof(i) }
         (1..3).map { |i| i || 0 }
+        (1..3).map { |i| :foo }
+        (1..3).map { |i| :foo.to_s.split.join('.') }
+        (1..3).map { :foo }
       )
       subject.catch(source).should be_valid
     end
diff --git a/src/ameba/rule/style/verbose_block.cr b/src/ameba/rule/style/verbose_block.cr
index 12bb0e0ba..d50490915 100644
--- a/src/ameba/rule/style/verbose_block.cr
+++ b/src/ameba/rule/style/verbose_block.cr
@@ -210,7 +210,6 @@ module Ameba::Rule::Style
       while obj.is_a?(Crystal::Call)
         obj = obj.obj
       end
-      return unless obj.is_a?(Crystal::Var)
 
       # only calls with a first argument used as a receiver are the valid game
       return unless obj == arg

From bf64c8242b893412dc0f9f0c3ad9a63e5c2b230b Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Mon, 8 Feb 2021 21:03:34 +0100
Subject: [PATCH 36/37] Bump to v0.14.0

---
 shard.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/shard.yml b/shard.yml
index e40c86dcd..e64b2a966 100644
--- a/shard.yml
+++ b/shard.yml
@@ -1,5 +1,5 @@
 name: ameba
-version: 0.13.4
+version: 0.14.0
 
 authors:
   - Vitalii Elenhaupt <velenhaupt@gmail.com>

From 3a1ee7fa218ecf3a833029360133a05ec5fd564c Mon Sep 17 00:00:00 2001
From: Vitalii Elenhaupt <velenhaupt@gmail.com>
Date: Thu, 11 Feb 2021 11:01:30 +0200
Subject: [PATCH 37/37] Correct yml examples

---
 src/ameba/rule/performance/chained_call_with_no_bang.cr | 2 +-
 src/ameba/rule/performance/compact_after_map.cr         | 2 +-
 src/ameba/rule/performance/flatten_after_map.cr         | 2 +-
 src/ameba/rule/performance/map_instead_of_block.cr      | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/ameba/rule/performance/chained_call_with_no_bang.cr b/src/ameba/rule/performance/chained_call_with_no_bang.cr
index d7f827ae5..22a57c780 100644
--- a/src/ameba/rule/performance/chained_call_with_no_bang.cr
+++ b/src/ameba/rule/performance/chained_call_with_no_bang.cr
@@ -25,7 +25,7 @@ module Ameba::Rule::Performance
   # YAML configuration example:
   #
   # ```
-  # Performance/ChainedCallWithNoBang
+  # Performance/ChainedCallWithNoBang:
   #   Enabled: true
   #   CallNames:
   #     - uniq
diff --git a/src/ameba/rule/performance/compact_after_map.cr b/src/ameba/rule/performance/compact_after_map.cr
index 77f542cf2..63184498d 100644
--- a/src/ameba/rule/performance/compact_after_map.cr
+++ b/src/ameba/rule/performance/compact_after_map.cr
@@ -16,7 +16,7 @@ module Ameba::Rule::Performance
   # YAML configuration example:
   #
   # ```
-  # Performance/CompactAfterMap
+  # Performance/CompactAfterMap:
   #   Enabled: true
   # ```
   class CompactAfterMap < Base
diff --git a/src/ameba/rule/performance/flatten_after_map.cr b/src/ameba/rule/performance/flatten_after_map.cr
index 631c656d0..18ee2f8ab 100644
--- a/src/ameba/rule/performance/flatten_after_map.cr
+++ b/src/ameba/rule/performance/flatten_after_map.cr
@@ -16,7 +16,7 @@ module Ameba::Rule::Performance
   # YAML configuration example:
   #
   # ```
-  # Performance/FlattenAfterMap
+  # Performance/FlattenAfterMap:
   #   Enabled: true
   # ```
   class FlattenAfterMap < Base
diff --git a/src/ameba/rule/performance/map_instead_of_block.cr b/src/ameba/rule/performance/map_instead_of_block.cr
index 5e8036173..377130fc6 100644
--- a/src/ameba/rule/performance/map_instead_of_block.cr
+++ b/src/ameba/rule/performance/map_instead_of_block.cr
@@ -19,7 +19,7 @@ module Ameba::Rule::Performance
   # YAML configuration example:
   #
   # ```
-  # Performance/MapInsteadOfBlock
+  # Performance/MapInsteadOfBlock:
   #   Enabled: true
   # ```
   class MapInsteadOfBlock < Base