def _function_definition(self):
"""Function definition rule.
function_definition -> 'def' ID '(' (ID (',' ID)*)? ')' slist
"""
self._match(tokens.DEF)
node = AST(tokens.FUNC_DEF)
id_token = self._lookahead_token(0)
node.add_child(AST(id_token))
func_symbol = FunctionSymbol(id_token.text, self.current_scope)
func_symbol.scope = self.current_scope
self.current_scope.define(func_symbol)
self.current_scope = func_symbol
self._match(tokens.ID)
self._match(tokens.LPAREN)
if self._lookahead_type(0) == tokens.ID:
node.add_child(AST(self._lookahead_token(0)))
variable_symbol = VariableSymbol(self._lookahead_token(0).text)
variable_symbol.scope = self.current_scope
self.current_scope.define(variable_symbol)
self._match(tokens.ID)
while self._lookahead_type(0) == tokens.COMMA:
self._match(tokens.COMMA)
node.add_child(AST(self._lookahead_token(0)))
variable_symbol = VariableSymbol(self._lookahead_token(0).text)
self.current_scope.define(variable_symbol)
variable_symbol.scope = self.current_scope
self._match(tokens.ID)
self._match(tokens.RPAREN)
self.current_scope = LocalScope(self.current_scope)
block_ast = self._slist()
func_symbol.block_ast = block_ast
node.add_child(block_ast)
# pop LocalScope
self.current_scope = self.current_scope.get_enclosing_scope()
# pop FunctionSymbol
self.current_scope = self.current_scope.get_enclosing_scope()
return node
def _assign(self):
"""Assign rule.
assign -> ID '=' expr
"""
node = AST(tokens.ASSIGN)
node.add_child(AST(self._lookahead_token(0)))
variable_symbol = VariableSymbol(self._lookahead_token(0).text)
variable_symbol.scope = self.current_scope
self.current_scope.define(variable_symbol)
self._match(tokens.ID)
self._match(tokens.ASSIGN)
node.add_child(self._expr())
return node