statement_sequence,air_node: Generalize for-each loops

Closes #135.

asteria/compiler/statement_sequence.cpp

@@ -927,25 +927,27 @@ do_accept_for_complement_range_opt(Token_Stream& tstrm, const Source_Location& o
                                    Scope_Flags scfl)
   {
     // for-complement-range ::=
-    //   "each" identifier "," identifier "->" expression ")" statement
+    //   "each" identifier ( ( "," | ":" | "=" ) identifier ) ? "->" expression ")" statement
     auto qkwrd = do_accept_keyword_opt(tstrm, { keyword_each });
     if(!qkwrd)
       return nullopt;
 
-    auto qkname = do_accept_identifier_opt(tstrm, true);
-    if(!qkname)
+    cow_string key;
+    auto qmapped = do_accept_identifier_opt(tstrm, true);
+    if(!qmapped)
       throw Compiler_Error(Compiler_Error::M_status(),
                 compiler_status_identifier_expected, tstrm.next_sloc());
 
-    auto kpunct = do_accept_punctuator_opt(tstrm, { punctuator_comma });
-    if(!kpunct)
-      throw Compiler_Error(Compiler_Error::M_status(),
-                compiler_status_comma_expected, tstrm.next_sloc());
-
-    auto qvname = do_accept_identifier_opt(tstrm, true);
-    if(!qvname)
-      throw Compiler_Error(Compiler_Error::M_status(),
-                compiler_status_identifier_expected, tstrm.next_sloc());
+    auto kpunct = do_accept_punctuator_opt(tstrm, { punctuator_comma, punctuator_colon, punctuator_assign });
+    if(kpunct) {
+      // Move the first identifier into the key and expect the name for mapped
+      // references.
+      key = ::std::move(*qmapped);
+      qmapped = do_accept_identifier_opt(tstrm, true);
+      if(!qmapped)
+        throw Compiler_Error(Compiler_Error::M_status(),
+                  compiler_status_identifier_expected, tstrm.next_sloc());
+    }
 
     kpunct = do_accept_punctuator_opt(tstrm, { punctuator_arrow });
     if(!kpunct)
@@ -969,9 +971,8 @@ do_accept_for_complement_range_opt(Token_Stream& tstrm, const Source_Location& o
       throw Compiler_Error(Compiler_Error::M_status(),
                 compiler_status_statement_expected, tstrm.next_sloc());
 
-    Statement::S_for_each xstmt = { ::std::move(*qkname), ::std::move(*qvname),
-                                    ::std::move(sloc_init), ::std::move(*qinit),
-                                    ::std::move(*qblock) };
+    Statement::S_for_each xstmt = { ::std::move(key), ::std::move(*qmapped), ::std::move(sloc_init),
+                                    ::std::move(*qinit), ::std::move(*qblock) };
     return ::std::move(xstmt);
   }
 

asteria/runtime/air_node.cpp

@@ -339,7 +339,8 @@ rebind_opt(Abstract_Context& ctx) const
         S_for_each_statement bound = altr;
 
         Analytic_Context ctx_for(Analytic_Context::M_plain(), ctx);
-        ctx_for.insert_named_reference(altr.name_key);
+        if(!altr.name_key.empty())
+          ctx_for.insert_named_reference(altr.name_key);
         ctx_for.insert_named_reference(altr.name_mapped);
         do_rebind_nodes(dirty, bound.code_init, ctx_for);
 
@@ -1123,9 +1124,8 @@ solidify(AVMC_Queue& queue) const
             Executive_Context ctx_for(Executive_Context::M_plain(), ctx);
 
             // Create key and mapped references.
-            auto& key = ctx_for.insert_named_reference(sp.name_key);
-            auto& mapped = ctx_for.insert_named_reference(sp.name_mapped);
             refcnt_ptr<Variable> kvar;
+            auto& mapped = ctx_for.insert_named_reference(sp.name_mapped);
 
             // Evaluate the range initializer and set the range up, which isn't
             // going to change for all loops.
@@ -1140,19 +1140,21 @@ solidify(AVMC_Queue& queue) const
             }
             else if(range.is_array()) {
               const auto& arr = range.as_array();
+              mapped.push_modifier(Reference_Modifier::S_array_head());  // placeholder
               for(int64_t i = 0;  i < arr.ssize();  ++i) {
                 // Set the key variable which is the subscript of the mapped
                 // element in the array.
-                if(!kvar) {
-                  kvar = ctx.global().garbage_collector()->create_variable();
-                  key.set_variable(kvar);
+                if(!sp.name_key.empty()) {
+                  if(!kvar) {
+                    kvar = ctx.global().garbage_collector()->create_variable();
+                    ctx_for.insert_named_reference(sp.name_key).set_variable(kvar);
+                  }
+                  kvar->initialize(i);
+                  kvar->set_immutable();
                 }
-                else
-                  mapped.pop_modifier();
-
-                kvar->initialize(i);
-                kvar->set_immutable();
 
+                // Set the mapped reference.
+                mapped.pop_modifier();
                 Reference_Modifier::S_array_index xmod = { i };
                 mapped.push_modifier(::std::move(xmod));
                 mapped.dereference_readonly();
@@ -1171,19 +1173,21 @@ solidify(AVMC_Queue& queue) const
             }
             else if(range.is_object()) {
               const auto& obj = range.as_object();
+              mapped.push_modifier(Reference_Modifier::S_array_head());  // placeholder
               for(auto it = obj.begin();  it != obj.end();  ++it) {
                 // Set the key variable which is the name of the mapped element
                 // in the object.
-                if(!kvar) {
-                  kvar = ctx.global().garbage_collector()->create_variable();
-                  key.set_variable(kvar);
+                if(!sp.name_key.empty()) {
+                  if(!kvar) {
+                    kvar = ctx.global().garbage_collector()->create_variable();
+                    ctx_for.insert_named_reference(sp.name_key).set_variable(kvar);
+                  }
+                  kvar->initialize(it->first.rdstr());
+                  kvar->set_immutable();
                 }
-                else
-                  mapped.pop_modifier();
-
-                kvar->initialize(it->first.rdstr());
-                kvar->set_immutable();
 
+                // Set the mapped reference.
+                mapped.pop_modifier();
                 Reference_Modifier::S_object_key xmod = { it->first };
                 mapped.push_modifier(::std::move(xmod));
                 mapped.dereference_readonly();
@@ -1197,9 +1201,6 @@ solidify(AVMC_Queue& queue) const
                 else if(::rocket::is_none_of(status, { air_status_next, air_status_continue_unspec,
                                                        air_status_continue_for }))
                   break;
-
-                // Restore the mapped reference.
-                mapped.pop_modifier();
               }
               return status;
             }

doc/syntax.txt

@@ -128,7 +128,7 @@ for-complement ::=
 	for-complement-range | for-complement-triplet
 
 for-complement-range ::=
-	"each" identifier "," identifier "->" expression ")" statement
+	"each" identifier ( ( "," | ":" | "=" ) identifier ) ? "->" expression ")" statement
 
 for-complement-triplet ::=
 	for-initializer expression ? ";" expression ? ")" statement

test/Makefile.inc.am

@@ -57,6 +57,7 @@ check_PROGRAMS +=  \
   %reldir%/ptc_hooks_throw.test  \
   %reldir%/ptc_hooks_return.test  \
   %reldir%/switch_defer.test  \
+  %reldir%/for_each.test  \
   ${END}
 
 EXTRA_DIST +=  \

test/for_each.cpp

@@ -0,0 +1,40 @@
+// This file is part of Asteria.
+// Copyleft 2018 - 2023, LH_Mouse. All wrongs reserved.
+
+#include "utils.hpp"
+#include "../asteria/simple_script.hpp"
+using namespace ::asteria;
+
+int main()
+  {
+    Simple_Script code;
+    code.reload_string(
+      sref(__FILE__), __LINE__, sref(R"__(
+///////////////////////////////////////////////////////////////////////////////
+
+        var output;
+
+        output = "";
+        for(each k, v -> ["a","b","c"])
+          output += std.string.format("$1=$2;", k, v);
+        assert output == "0=a;1=b;2=c;";
+
+        output = "";
+        for(each k: v -> ["a","b","c"])
+          output += std.string.format("$1=$2;", k, v);
+        assert output == "0=a;1=b;2=c;";
+
+        output = "";
+        for(each k = v -> ["a","b","c"])
+          output += std.string.format("$1=$2;", k, v);
+        assert output == "0=a;1=b;2=c;";
+
+        output = "";
+        for(each v -> ["a","b","c"])
+          output += std.string.format("$1;", v);
+        assert output == "a;b;c;";
+
+///////////////////////////////////////////////////////////////////////////////
+      )__"));
+    code.execute();
+  }