interpreter.py

import os
import math
import string
import sys
try:
  from symboltable import SymbolTable
  from runtime import RTResult
  from errors import RTError
  from tokens import Tokens
except:
  from .symboltable import SymbolTable
  from .runtime import RTResult
  from .errors import RTError
  from .tokens import Tokens



#######################################
# VALUES
#######################################

class Value:
  def __init__(self):
    self.set_pos()
    self.set_context()

  def set_pos(self, pos_start=None, pos_end=None):
    self.pos_start = pos_start
    self.pos_end = pos_end
    return self

  def set_context(self, context=None):
    self.context = context
    return self

  def added_to(self, other):
    return None, self.illegal_operation(other)

  def subbed_by(self, other):
    return None, self.illegal_operation(other)

  def multed_by(self, other):
    return None, self.illegal_operation(other)

  def dived_by(self, other):
    return None, self.illegal_operation(other)

  def powed_by(self, other):
    return None, self.illegal_operation(other)

  def get_comparison_eq(self, other):
    return None, self.illegal_operation(other)

  def get_comparison_ne(self, other):
    return None, self.illegal_operation(other)

  def get_comparison_lt(self, other):
    return None, self.illegal_operation(other)

  def get_comparison_gt(self, other):
    return None, self.illegal_operation(other)

  def get_comparison_lte(self, other):
    return None, self.illegal_operation(other)

  def get_comparison_gte(self, other):
    return None, self.illegal_operation(other)

  def anded_by(self, other):
    return None, self.illegal_operation(other)

  def ored_by(self, other):
    return None, self.illegal_operation(other)

  def notted(self, other):
    return None, self.illegal_operation(other)

  def execute(self, args):
    return RTResult().failure(self.illegal_operation())

  def copy(self):
    raise Exception('No copy method defined')

  def is_true(self):
    return False

  def illegal_operation(self, other=None):
    if not other: other = self
    return RTError(
      self.pos_start, other.pos_end,
      'Illegal operation',
      self.context
    )

class Number(Value):
  def __init__(self, value):
    super().__init__()
    self.value = value

  def added_to(self, other):
    if isinstance(other, Number):
      return Number(self.value + other.value).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def subbed_by(self, other):
    if isinstance(other, Number):
      return Number(self.value - other.value).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def multed_by(self, other):
    if isinstance(other, Number):
      return Number(self.value * other.value).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def dived_by(self, other):
    if isinstance(other, Number):
      if other.value == 0:
        return None, RTError(
          other.pos_start, other.pos_end,
          'Division by zero',
          self.context
        )

      return Number(self.value / other.value).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def powed_by(self, other):
    if isinstance(other, Number):
      return Number(self.value ** other.value).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def get_comparison_eq(self, other):
    if isinstance(other, Number):
      return Number(int(self.value == other.value)).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def get_comparison_ne(self, other):
    if isinstance(other, Number):
      return Number(int(self.value != other.value)).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def get_comparison_lt(self, other):
    if isinstance(other, Number):
      return Number(int(self.value < other.value)).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def get_comparison_gt(self, other):
    if isinstance(other, Number):
      return Number(int(self.value > other.value)).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def get_comparison_lte(self, other):
    if isinstance(other, Number):
      return Number(int(self.value <= other.value)).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def get_comparison_gte(self, other):
    if isinstance(other, Number):
      return Number(int(self.value >= other.value)).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def anded_by(self, other):
    if isinstance(other, Number):
      return Number(int(self.value and other.value)).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def ored_by(self, other):
    if isinstance(other, Number):
      return Number(int(self.value or other.value)).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def notted(self):
    return Number(1 if self.value == 0 else 0).set_context(self.context), None

  def copy(self):
    copy = Number(self.value)
    copy.set_pos(self.pos_start, self.pos_end)
    copy.set_context(self.context)
    return copy

  def is_true(self):
    return self.value != 0

  def __str__(self):
    return str(self.value)
  
  def __repr__(self):
    return str(self.value)

Number.null = Number(0)
Number.false = Number(0)
Number.true = Number(1)
Number.math_PI = Number(math.pi)

class String(Value):
  def __init__(self, value):
    super().__init__()
    self.value = value

  def added_to(self, other):
    if isinstance(other, String):
      return String(self.value + other.value).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def multed_by(self, other):
    if isinstance(other, Number):
      return String(self.value * other.value).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def is_true(self):
    return len(self.value) > 0

  def copy(self):
    copy = String(self.value)
    copy.set_pos(self.pos_start, self.pos_end)
    copy.set_context(self.context)
    return copy

  def __str__(self):
    return self.value

  def __repr__(self):
    return f'"{self.value}"'

class PythonCode(Value):
  def __init__(self, value):
    super().__init__()
    self.value = value
    exec(self.value)

  def added_to(self, other):
    if isinstance(other, PythonCode):
      return PythonCode(self.value + other.value).set_context(self.context), None
    else:
      return None, Value.illegal_operation(self, other)

  def is_true(self):
    return len(self.value) > 0

  def copy(self):
    copy = PythonCode(self.value)
    copy.set_pos(self.pos_start, self.pos_end)
    copy.set_context(self.context)
    return copy

  def __str__(self):
    return self.value

  def __repr__(self):
    return f'`{self.value}`'

class List(Value):
  def __init__(self, elements):
    super().__init__()
    self.elements = elements

  def added_to(self, other):
    new_list = self.copy()
    new_list.elements.append(other)
    return new_list, None

  def subbed_by(self, other):
    if isinstance(other, Number):
      new_list = self.copy()
      try:
        new_list.elements.pop(other.value)
        return new_list, None
      except:
        return None, RTError(
          other.pos_start, other.pos_end,
          'Element at this index could not be removed from list because index is out of bounds',
          self.context
        )
    else:
      return None, Value.illegal_operation(self, other)

  def multed_by(self, other):
    if isinstance(other, List):
      new_list = self.copy()
      new_list.elements.extend(other.elements)
      return new_list, None
    else:
      return None, Value.illegal_operation(self, other)

  def dived_by(self, other):
    if isinstance(other, Number):
      try:
        return self.elements[other.value], None
      except:
        return None, RTError(
          other.pos_start, other.pos_end,
          'Element at this index could not be retrieved from list because index is out of bounds',
          self.context
        )
    else:
      return None, Value.illegal_operation(self, other)
  
  def copy(self):
    copy = List(self.elements)
    copy.set_pos(self.pos_start, self.pos_end)
    copy.set_context(self.context)
    return copy

  def __str__(self):
    return ", ".join([str(x) for x in self.elements])

  def __repr__(self):
    return f'[{", ".join([repr(x) for x in self.elements])}]'

class BaseFunction(Value):
  def __init__(self, name):
    super().__init__()
    self.name = name or "<anonymous>"

  def generate_new_context(self):
    new_context = Context(self.name, self.context, self.pos_start)
    new_context.symbol_table = SymbolTable(new_context.parent.symbol_table)
    return new_context

  def check_args(self, arg_names, args):
    res = RTResult()

    if len(args) > len(arg_names):
      return res.failure(RTError(
        self.pos_start, self.pos_end,
        f"{len(args) - len(arg_names)} too many args passed into {self}",
        self.context
      ))
    
    if len(args) < len(arg_names):
      return res.failure(RTError(
        self.pos_start, self.pos_end,
        f"{len(arg_names) - len(args)} too few args passed into {self}",
        self.context
      ))

    return res.success(None)

  def populate_args(self, arg_names, args, exec_ctx):
    for i in range(len(args)):
      arg_name = arg_names[i]
      arg_value = args[i]
      arg_value.set_context(exec_ctx)
      exec_ctx.symbol_table.set(arg_name, arg_value)

  def check_and_fix_default_args(self, arg_names, args):
    if self.name == "input" and (len(args) < len(arg_names)):
      args.append(String(""))

    if self.name == "input_int" and (len(args) < len(arg_names)):
      args.append(String(""))

    if self.name == "write" and (len(args) > len(arg_names)):
      full_arg = ""
      for i in range(0, len(args)):
        t = str(args[i])
        if i != 0:
          full_arg += f" {t}"

      cargs = str(args[0]) + full_arg
      args.clear()
      args.append(String(cargs))

  def check_and_populate_args(self, arg_names, args, exec_ctx):
    res = RTResult()
    self.check_and_fix_default_args(arg_names, args)
    res.register(self.check_args(arg_names, args))
    if res.should_return(): return res
    self.populate_args(arg_names, args, exec_ctx)
    return res.success(None)

class Function(BaseFunction):
  def __init__(self, name, body_node, arg_names, should_auto_return):
    super().__init__(name)
    self.body_node = body_node
    self.arg_names = arg_names
    self.should_auto_return = should_auto_return

  def execute(self, args):
    res = RTResult()
    interpreter = Interpreter()
    exec_ctx = self.generate_new_context()

    res.register(self.check_and_populate_args(self.arg_names, args, exec_ctx))
    if res.should_return(): return res

    value = res.register(interpreter.visit(self.body_node, exec_ctx))
    if res.should_return() and res.func_return_value == None: return res

    ret_value = (value if self.should_auto_return else None) or res.func_return_value or Number.null
    return res.success(ret_value)

  def copy(self):
    copy = Function(self.name, self.body_node, self.arg_names, self.should_auto_return)
    copy.set_context(self.context)
    copy.set_pos(self.pos_start, self.pos_end)
    return copy

  def __repr__(self):
    return f"<function {self.name}>"

class BuiltInFunction(BaseFunction):
  def __init__(self, name):
    super().__init__(name)

  def execute(self, args):
    res = RTResult()
    exec_ctx = self.generate_new_context()

    method_name = f'execute_{self.name}'
    method = getattr(self, method_name, self.no_visit_method)

    res.register(self.check_and_populate_args(method.arg_names, args, exec_ctx))
    if res.should_return(): return res

    return_value = res.register(method(exec_ctx))
    if res.should_return(): return res
    return res.success(return_value)
  
  def no_visit_method(self, node, context):
    raise Exception(f'No execute_{self.name} method defined')

  def copy(self):
    copy = BuiltInFunction(self.name)
    copy.set_context(self.context)
    copy.set_pos(self.pos_start, self.pos_end)
    return copy

  def __repr__(self):
    return f"<built-in function {self.name}>"

  #####################################

  def execute_write(self, exec_ctx):
    print(str(exec_ctx.symbol_table.get('value')).encode("utf8").decode(sys.stdout.encoding))
    f = open("_printed_",'a',encoding='utf8')
    print(str(exec_ctx.symbol_table.get('value')), file=f)
    f.close()
    return RTResult().success(Number.null)
  execute_write.arg_names = ['value']
  
  def execute_write_ret(self, exec_ctx):
    return RTResult().success(String(str(exec_ctx.symbol_table.get('value'))))
  execute_write_ret.arg_names = ['value']
  
  def execute_input(self, exec_ctx):
    text = input(exec_ctx.symbol_table.get('prompt'))
    return RTResult().success(String(text))
  execute_input.arg_names = ['prompt']


  def execute_input_int(self, exec_ctx):
    while True:
      text = input(exec_ctx.symbol_table.get('prompt'))
      try:
        number = int(text)
        break
      except ValueError:
        print(f"'{text}' must be an integer. Try again!")
    return RTResult().success(Number(number))
  execute_input_int.arg_names = ['prompt']

  def execute_clear(self, exec_ctx):
    os.system('cls' if os.name == 'nt' else 'cls') 
    return RTResult().success(Number.null)
  execute_clear.arg_names = []

  def execute_is_number(self, exec_ctx):
    is_number = isinstance(exec_ctx.symbol_table.get("value"), Number)
    return RTResult().success(Number.true if is_number else Number.false)
  execute_is_number.arg_names = ["value"]

  def execute_is_string(self, exec_ctx):
    is_number = isinstance(exec_ctx.symbol_table.get("value"), String)
    return RTResult().success(Number.true if is_number else Number.false)
  execute_is_string.arg_names = ["value"]

  def execute_is_list(self, exec_ctx):
    is_number = isinstance(exec_ctx.symbol_table.get("value"), List)
    return RTResult().success(Number.true if is_number else Number.false)
  execute_is_list.arg_names = ["value"]

  def execute_is_function(self, exec_ctx):
    is_number = isinstance(exec_ctx.symbol_table.get("value"), BaseFunction)
    return RTResult().success(Number.true if is_number else Number.false)
  execute_is_function.arg_names = ["value"]

  def execute_to_string(self, exec_ctx):
    result = String(str(exec_ctx.symbol_table.get("value")))
    if not isinstance(result, String):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "Couldn't convert to a string",
        exec_ctx
      ))
    return RTResult().success(result)
  execute_to_string.arg_names = ["value"]

  def execute_to_number(self, exec_ctx):
    if not (isinstance(exec_ctx.symbol_table.get("value"), String) or isinstance(exec_ctx.symbol_table.get("value"), Number)):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "Couldn't convert to an integer",
        exec_ctx
      ))

    result = Number(int(str(exec_ctx.symbol_table.get("value"))))
    return RTResult().success(result)
  execute_to_number.arg_names = ["value"]

  def execute_type_(self, exec_ctx):
    return RTResult().success(String(str(type(exec_ctx.symbol_table.get("value")))))
  execute_type_.arg_names = ['value']

  def execute_append(self, exec_ctx):
    list_ = exec_ctx.symbol_table.get("list")
    value = exec_ctx.symbol_table.get("value")

    if not isinstance(list_, List):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "First argument must be list",
        exec_ctx
      ))

    list_.elements.append(value)
    return RTResult().success(Number.null)
  execute_append.arg_names = ["list", "value"]

  def execute_pop(self, exec_ctx):
    list_ = exec_ctx.symbol_table.get("list")
    index = exec_ctx.symbol_table.get("index")

    if not isinstance(list_, List):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "First argument must be list",
        exec_ctx
      ))

    if not isinstance(index, Number):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "Second argument must be number",
        exec_ctx
      ))

    try:
      element = list_.elements.pop(index.value)
    except:
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        'Element at this index could not be removed from list because index is out of bounds',
        exec_ctx
      ))
    return RTResult().success(element)
  execute_pop.arg_names = ["list", "index"]

  def execute_select(self, exec_ctx):
    list_ = exec_ctx.symbol_table.get("list")
    index = exec_ctx.symbol_table.get("index")

    if not isinstance(list_, List):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "First argument must be list",
        exec_ctx
      ))

    if not isinstance(index, Number):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "Second argument must be number",
        exec_ctx
      ))

    try:
      element = list_.elements[index.value]
    except:
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        'Element at this index could not be removed from list because index is out of bounds',
        exec_ctx
      ))
    return RTResult().success(element)
  execute_select.arg_names = ["list", "index"]

  def execute_extend(self, exec_ctx):
    listA = exec_ctx.symbol_table.get("listA")
    listB = exec_ctx.symbol_table.get("listB")

    if not isinstance(listA, List):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "First argument must be list",
        exec_ctx
      ))

    if not isinstance(listB, List):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "Second argument must be list",
        exec_ctx
      ))

    listA.elements.extend(listB.elements)
    return RTResult().success(Number.null)
  execute_extend.arg_names = ["listA", "listB"]

  def execute_len(self, exec_ctx):
    list_ = exec_ctx.symbol_table.get("list")

    if not isinstance(list_, List):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "Argument must be list",
        exec_ctx
      ))

    return RTResult().success(Number(len(list_.elements)))
  execute_len.arg_names = ["list"]

  def execute_import_(self, exec_ctx):
    fn = exec_ctx.symbol_table.get("fn")

    if not isinstance(fn, String):
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        "Second argument must be string",
        exec_ctx
      ))

    fn = fn.value

    try:
      with open(fn, "r", encoding="utf-8") as f:
        script = f.read()
    except Exception as e:
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        f"Failed to import script \"{fn}\"\n" + str(e),
        exec_ctx
      ))

    _, error = _import(fn, script)
    
    if error:
      return RTResult().failure(RTError(
        self.pos_start, self.pos_end,
        f"Failed to finish executing script \"{fn}\"\n" +
        error.as_string(),
        exec_ctx
      ))

    return RTResult().success(Number.null)
  execute_import_.arg_names = ["fn"]

BuiltInFunction.write       = BuiltInFunction("write")
BuiltInFunction.write_ret   = BuiltInFunction("write_ret")
BuiltInFunction.input       = BuiltInFunction("input")
BuiltInFunction.input_int   = BuiltInFunction("input_int")
BuiltInFunction.clear       = BuiltInFunction("clear")
BuiltInFunction.is_number   = BuiltInFunction("is_number")
BuiltInFunction.is_string   = BuiltInFunction("is_string")
BuiltInFunction.is_list     = BuiltInFunction("is_list")
BuiltInFunction.is_function = BuiltInFunction("is_function")
BuiltInFunction.to_string   = BuiltInFunction("to_string")
BuiltInFunction.to_number   = BuiltInFunction("to_number")
BuiltInFunction.type_       = BuiltInFunction("type_")
BuiltInFunction.append      = BuiltInFunction("append")
BuiltInFunction.pop         = BuiltInFunction("pop")
BuiltInFunction.select      = BuiltInFunction("select")
BuiltInFunction.extend      = BuiltInFunction("extend")
BuiltInFunction.len					= BuiltInFunction("len")
BuiltInFunction.import_		  = BuiltInFunction("import_")
#######################################
# CONTEXT
#######################################

class Context:
  def __init__(self, display_name, parent=None, parent_entry_pos=None):
    self.display_name = display_name
    self.parent = parent
    self.parent_entry_pos = parent_entry_pos
    self.symbol_table = None

#######################################
# INTERPRETER
#######################################

class Interpreter:
  def visit(self, node, context):
    method_name = f'visit_{type(node).__name__}'
    method = getattr(self, method_name, self.no_visit_method)
    return method(node, context)

  def no_visit_method(self, node, context):
    raise Exception(f'No visit_{type(node).__name__} method defined')

  ###################################

  def visit_NumberNode(self, node, context):
    return RTResult().success(
      Number(node.tok.value).set_context(context).set_pos(node.pos_start, node.pos_end)
    )

  def visit_StringNode(self, node, context):
    return RTResult().success(
      String(node.tok.value).set_context(context).set_pos(node.pos_start, node.pos_end)
    )

  def visit_PythonCodeNode(self, node, context):
    return RTResult().success(
      PythonCode(node.tok.value).set_context(context).set_pos(node.pos_start, node.pos_end)
    )

  def visit_ListNode(self, node, context):
    res = RTResult()
    elements = []

    for element_node in node.element_nodes:
      elements.append(res.register(self.visit(element_node, context)))
      if res.should_return(): return res

    return res.success(
      List(elements).set_context(context).set_pos(node.pos_start, node.pos_end)
    )

  def visit_VarAccessNode(self, node, context):
    res = RTResult()
    var_name = node.var_name_tok.value
    value = context.symbol_table.get(var_name)

    if not value:
      return res.failure(RTError(
        node.pos_start, node.pos_end,
        f"'{var_name}' is not defined",
        context
      ))

    value = value.copy().set_pos(node.pos_start, node.pos_end).set_context(context)
    return res.success(value)

  def visit_VarAssignNode(self, node, context):
    res = RTResult()
    var_name = node.var_name_tok.value
    value = res.register(self.visit(node.value_node, context))
    if res.should_return(): return res

    context.symbol_table.set(var_name, value)
    return res.success(value)

  def visit_BinOpNode(self, node, context):
    res = RTResult()
    left = res.register(self.visit(node.left_node, context))
    if res.should_return(): return res
    right = res.register(self.visit(node.right_node, context))
    if res.should_return(): return res

    if node.op_tok.type == Tokens['PLUS']:
      result, error = left.added_to(right)
    elif node.op_tok.type == Tokens['MINUS']:
      result, error = left.subbed_by(right)
    elif node.op_tok.type == Tokens['MUL']:
      result, error = left.multed_by(right)
    elif node.op_tok.type == Tokens['DIV']:
      result, error = left.dived_by(right)
    elif node.op_tok.type == Tokens['POWER']:
      result, error = left.powed_by(right)
    elif node.op_tok.type == Tokens['EQEQ']:
      result, error = left.get_comparison_eq(right)
    elif node.op_tok.type == Tokens['NOTEQ']:
      result, error = left.get_comparison_ne(right)
    elif node.op_tok.type == Tokens['LESSTHAN']:
      result, error = left.get_comparison_lt(right)
    elif node.op_tok.type == Tokens['GREATERTHAN']:
      result, error = left.get_comparison_gt(right)
    elif node.op_tok.type == Tokens['LTEQ']:
      result, error = left.get_comparison_lte(right)
    elif node.op_tok.type == Tokens['GTEQ']:
      result, error = left.get_comparison_gte(right)
    elif node.op_tok.matches(Tokens['KEYWORD'], 'and'):
      result, error = left.anded_by(right)
    elif node.op_tok.matches(Tokens['KEYWORD'], 'සහ'):
      result, error = left.anded_by(right)
    elif node.op_tok.matches(Tokens['KEYWORD'], 'or'):
      result, error = left.ored_by(right)
    elif node.op_tok.matches(Tokens['KEYWORD'], 'හෝ'):
      result, error = left.ored_by(right)

    if error:
      return res.failure(error)
    else:
      return res.success(result.set_pos(node.pos_start, node.pos_end))

  def visit_UnaryOpNode(self, node, context):
    res = RTResult()
    number = res.register(self.visit(node.node, context))
    if res.should_return(): return res

    error = None

    if node.op_tok.type == Tokens['MINUS']:
      number, error = number.multed_by(Number(-1))
    elif node.op_tok.matches(Tokens['KEYWORD'], 'not') or node.op_tok.matches(Tokens['KEYWORD'], 'නොමැත') or node.op_tok.matches(Tokens['KEYWORD'], 'නොව') or node.op_tok.matches(Tokens['KEYWORD'], 'නැත') or node.op_tok.matches(Tokens['KEYWORD'], 'නොවේ') or node.op_tok.matches(Tokens['KEYWORD'], 'නොව'):
      number, error = number.notted()

    if error:
      return res.failure(error)
    else:
      return res.success(number.set_pos(node.pos_start, node.pos_end))

  def visit_IfNode(self, node, context):
    res = RTResult()

    for condition, expr, should_return_null in node.cases:
      condition_value = res.register(self.visit(condition, context))
      if res.should_return(): return res

      if condition_value.is_true():
        expr_value = res.register(self.visit(expr, context))
        if res.should_return(): return res
        return res.success(Number.null if should_return_null else expr_value)

    if node.else_case:
      expr, should_return_null = node.else_case
      expr_value = res.register(self.visit(expr, context))
      if res.should_return(): return res
      return res.success(Number.null if should_return_null else expr_value)

    return res.success(Number.null)

  def visit_ForNode(self, node, context):
    res = RTResult()
    elements = []

    start_value = res.register(self.visit(node.start_value_node, context))
    if res.should_return(): return res

    end_value = res.register(self.visit(node.end_value_node, context))
    if res.should_return(): return res

    if node.step_value_node:
      step_value = res.register(self.visit(node.step_value_node, context))
      if res.should_return(): return res
    else:
      step_value = Number(1)

    i = start_value.value

    if step_value.value >= 0:
      condition = lambda: i < end_value.value
    else:
      condition = lambda: i > end_value.value
    
    while condition():
      context.symbol_table.set(node.var_name_tok.value, Number(i))
      i += step_value.value

      value = res.register(self.visit(node.body_node, context))
      if res.should_return() and res.loop_should_continue == False and res.loop_should_break == False: return res
      
      if res.loop_should_continue:
        continue
      
      if res.loop_should_break:
        break

      elements.append(value)

    return res.success(
      Number.null if node.should_return_null else
      List(elements).set_context(context).set_pos(node.pos_start, node.pos_end)
    )

  def visit_WhileNode(self, node, context):
    res = RTResult()
    elements = []

    while True:
      condition = res.register(self.visit(node.condition_node, context))
      if res.should_return(): return res

      if not condition.is_true():
        break

      value = res.register(self.visit(node.body_node, context))
      if res.should_return() and res.loop_should_continue == False and res.loop_should_break == False: return res

      if res.loop_should_continue:
        continue
      
      if res.loop_should_break:
        break

      elements.append(value)

    return res.success(
      Number.null if node.should_return_null else
      List(elements).set_context(context).set_pos(node.pos_start, node.pos_end)
    )

  def visit_FuncDefNode(self, node, context):
    res = RTResult()

    func_name = node.var_name_tok.value if node.var_name_tok else None
    body_node = node.body_node
    arg_names = [arg_name.value for arg_name in node.arg_name_toks]
    func_value = Function(func_name, body_node, arg_names, node.should_auto_return).set_context(context).set_pos(node.pos_start, node.pos_end)
    
    if node.var_name_tok:
      context.symbol_table.set(func_name, func_value)

    return res.success(func_value)

  def visit_CallNode(self, node, context):
    res = RTResult()
    args = []

    value_to_call = res.register(self.visit(node.node_to_call, context))
    if res.should_return(): return res
    value_to_call = value_to_call.copy().set_pos(node.pos_start, node.pos_end)

    for arg_node in node.arg_nodes:
      args.append(res.register(self.visit(arg_node, context)))
      if res.should_return(): return res

    return_value = res.register(value_to_call.execute(args))
    if res.should_return(): return res
    return_value = return_value.copy().set_pos(node.pos_start, node.pos_end).set_context(context)
    return res.success(return_value)

  def visit_ReturnNode(self, node, context):
    res = RTResult()

    if node.node_to_return:
      value = res.register(self.visit(node.node_to_return, context))
      if res.should_return(): return res
    else:
      value = Number.null
    
    return res.success_return(value)

  def visit_ContinueNode(self, node, context):
    return RTResult().success_continue()

  def visit_BreakNode(self, node, context):
    return RTResult().success_break()
#######################################
# RUN
#######################################

global_symbol_table = SymbolTable()
global_symbol_table.set("null", Number.null)
global_symbol_table.set("false", Number.false)
global_symbol_table.set("true", Number.true)
global_symbol_table.set("math_pi", Number.math_PI)
global_symbol_table.set("write", BuiltInFunction.write)
global_symbol_table.set("preturn", BuiltInFunction.write_ret)
global_symbol_table.set("input", BuiltInFunction.input)
global_symbol_table.set("int_input", BuiltInFunction.input_int)
global_symbol_table.set("clear", BuiltInFunction.clear)
global_symbol_table.set("cls", BuiltInFunction.clear)
global_symbol_table.set("is_num", BuiltInFunction.is_number)
global_symbol_table.set("is_str", BuiltInFunction.is_string)
global_symbol_table.set("is_list", BuiltInFunction.is_list)
global_symbol_table.set("is_function", BuiltInFunction.is_function)
global_symbol_table.set("to_str", BuiltInFunction.to_string)
global_symbol_table.set("to_num", BuiltInFunction.to_number)
global_symbol_table.set("type", BuiltInFunction.type_)
global_symbol_table.set("append", BuiltInFunction.append)
global_symbol_table.set("pop", BuiltInFunction.pop)
global_symbol_table.set("select", BuiltInFunction.select)
global_symbol_table.set("extend", BuiltInFunction.extend)
global_symbol_table.set("len", BuiltInFunction.len)
global_symbol_table.set("import", BuiltInFunction.import_)

def _import(fn, text):
  try:
    from lexer import Lexer
    from _parser import Parser
  except:
    from .lexer import Lexer
    from ._parser import Parser
  # Generate tokens
  lexer = Lexer(fn, text)
  tokens, error = lexer.create_tokens()
  if error: return None, error
  
  # Generate AST
  parser = Parser(tokens)
  ast = parser.parse()
  if ast.error: return None, ast.error

  # Run program
  interpreter = Interpreter()
  context = Context('<program>')
  context.symbol_table = global_symbol_table
  result = interpreter.visit(ast.node, context)

  return result.value, result.error