Implement handling of arrow functions in the parser

src/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "v8.h"
 
 #include "api.h"
 #include "ast.h"
 #include "bootstrapper.h"
 #include "char-predicates-inl.h"
@@ skipping 664 matching lines @@
 
 
 Handle<String> ParserTraits::NextLiteralString(Scanner* scanner,
                                                PretenureFlag tenured) {
   return scanner->AllocateNextLiteralString(parser_->isolate(), tenured);
 }
 
 
 Expression* ParserTraits::ThisExpression(
     Scope* scope,
-    AstNodeFactory<AstConstructionVisitor>* factory) {
-  return factory->NewVariableProxy(scope->receiver());
+    AstNodeFactory<AstConstructionVisitor>* factory,
+    int pos) {
+  return factory->NewVariableProxy(scope->receiver(), pos);
 }
 
 
 Literal* ParserTraits::ExpressionFromLiteral(
     Token::Value token, int pos,
     Scanner* scanner,
     AstNodeFactory<AstConstructionVisitor>* factory) {
   Factory* isolate_factory = parser_->isolate()->factory();
   switch (token) {
     case Token::NULL_LITERAL:
@@ skipping 82 matching lines @@
       pending_error_message_(NULL),
       pending_error_char_arg_(NULL) {
   ASSERT(!script_.is_null());
   isolate_->set_ast_node_id(0);
   set_allow_harmony_scoping(!info->is_native() && FLAG_harmony_scoping);
   set_allow_modules(!info->is_native() && FLAG_harmony_modules);
   set_allow_natives_syntax(FLAG_allow_natives_syntax || info->is_native());
   set_allow_lazy(false);  // Must be explicitly enabled.
   set_allow_generators(FLAG_harmony_generators);
   set_allow_for_of(FLAG_harmony_iteration);
+  set_allow_arrow_functions(FLAG_harmony_arrow_functions);
   set_allow_harmony_numeric_literals(FLAG_harmony_numeric_literals);
 }
 
 
 FunctionLiteral* Parser::ParseProgram() {
   // TODO(bmeurer): We temporarily need to pass allow_nesting = true here,
   // see comment for HistogramTimerScope class.
   HistogramTimerScope timer_scope(isolate()->counters()->parse(), true);
   Handle<String> source(String::cast(script_->source()));
   isolate()->counters()->total_parse_size()->Increment(source->length());
@@ skipping 116 matching lines @@
           scope_,
           body,
           function_state.materialized_literal_count(),
           function_state.expected_property_count(),
           function_state.handler_count(),
           0,
           FunctionLiteral::kNoDuplicateParameters,
           FunctionLiteral::ANONYMOUS_EXPRESSION,
           FunctionLiteral::kGlobalOrEval,
           FunctionLiteral::kNotParenthesized,
-          FunctionLiteral::kNotGenerator,
+          FunctionLiteral::kNormalFunction,
           0);
       result->set_ast_properties(factory()->visitor()->ast_properties());
       result->set_dont_optimize_reason(
           factory()->visitor()->dont_optimize_reason());
     } else if (stack_overflow()) {
       isolate()->StackOverflow();
     } else {
       ThrowPendingError();
     }
   }
@@ skipping 66 matching lines @@
     original_scope_ = scope;
     FunctionState function_state(&function_state_, &scope_, scope, zone());
     ASSERT(scope->strict_mode() == SLOPPY || info()->strict_mode() == STRICT);
     ASSERT(info()->strict_mode() == shared_info->strict_mode());
     scope->SetStrictMode(shared_info->strict_mode());
     FunctionLiteral::FunctionType function_type = shared_info->is_expression()
         ? (shared_info->is_anonymous()
               ? FunctionLiteral::ANONYMOUS_EXPRESSION
               : FunctionLiteral::NAMED_EXPRESSION)
         : FunctionLiteral::DECLARATION;
+    bool is_generator = shared_info->is_generator();
     bool ok = true;
-    result = ParseFunctionLiteral(name,
-                                  Scanner::Location::invalid(),
-                                  false,  // Strict mode name already checked.
-                                  shared_info->is_generator(),
-                                  RelocInfo::kNoPosition,
-                                  function_type,
-                                  &ok);
+
+    if (shared_info->is_arrow()) {

[marja, 2014/05/26 12:46:06]

Probably the same refactoring applies to SharedInfo, instead of "is_generator"
and "is_arrow" you could have "type" (normal, generator, arrow).

+      ASSERT(!is_generator);
+      result =
+          reinterpret_cast<FunctionLiteral*>(ParseArrowFunctionLiteral(&ok));
+    } else {
+      result = ParseFunctionLiteral(name,
+                                    Scanner::Location::invalid(),
+                                    false,  // Strict mode name already checked.
+                                    is_generator,
+                                    RelocInfo::kNoPosition,
+                                    function_type,
+                                    &ok);
+    }
     // Make sure the results agree.
     ASSERT(ok == (result != NULL));
   }
 
   // Make sure the target stack is empty.
   ASSERT(target_stack_ == NULL);
 
   if (result == NULL) {
     if (stack_overflow()) {
       isolate()->StackOverflow();
@@ skipping 2229 matching lines @@
   Smi* literal_type = Smi::cast(value->get(kLiteralTypeSlot));
   return static_cast<LiteralType>(literal_type->value());
 }
 
 
 Handle<FixedArray> CompileTimeValue::GetElements(Handle<FixedArray> value) {
   return Handle<FixedArray>(FixedArray::cast(value->get(kElementsSlot)));
 }
 
 
+Vector<VariableProxy*> ParserTraits::ParameterListFromExpression(
+    Expression* expression, bool* ok) {
+
+  // Parsing the parameter list of an arrow function does not have parameters
+  // (as in: () => ...) returns NULL, so expression being NULL is not an error,
+  // but an valid empty parameter list.
+  if (expression == NULL)
+    return Vector<VariableProxy*>::empty();
+
+  const char* error_token = NULL;
+  Collector<VariableProxy*> collector;
+
+  while (expression->IsBinaryOperation()) {
+    BinaryOperation* binop = expression->AsBinaryOperation();
+
+    if (binop->op() != Token::COMMA) {
+      error_token = Token::String(expression->AsBinaryOperation()->op());
+      break;
+    }
+
+    expression = binop->right();
+    if (!expression->IsVariableProxy()) {
+      error_token = "";
+      break;
+    }
+    if (expression->AsVariableProxy()->is_this()) {
+      error_token = Token::String(Token::THIS);
+      break;
+    }
+
+    collector.Add(expression->AsVariableProxy());
+    expression = binop->left();
+  }
+
+  // No errors were found in the loop above, try to add the remaining item.
+  if (error_token == NULL) {
+    if (!expression->IsVariableProxy()) {
+      error_token = "";
+    } else if (expression->AsVariableProxy()->is_this()) {
+      error_token = Token::String(Token::THIS);
+    } else {
+      collector.Add(expression->AsVariableProxy());
+      return collector.ToVector();
+    }
+  }
+
+  // Report errors.
+  ASSERT_NE(error_token, NULL);
+  int error_pos = expression->position();
+  int error_token_len = strlen(error_token);
+  ParserTraits::ReportMessageAt(
+      Scanner::Location(error_pos,
+                        error_pos + error_token_len ? error_token_len : 1),
+      "unexpected_token",
+      error_token);
+  *ok = false;
+  return Vector<VariableProxy*>::empty();
+}
+
+
 FunctionLiteral* Parser::ParseFunctionLiteral(
     Handle<String> function_name,
     Scanner::Location function_name_location,
     bool name_is_strict_reserved,
     bool is_generator,
     int function_token_pos,
     FunctionLiteral::FunctionType function_type,
     bool* ok) {
   // Function ::
   //   '(' FormalParameterList? ')' '{' FunctionBody '}'
@@ skipping 227 matching lines @@
                         CHECK_OK);
     }
     ast_properties = *factory()->visitor()->ast_properties();
     dont_optimize_reason = factory()->visitor()->dont_optimize_reason();
   }
 
   if (allow_harmony_scoping() && strict_mode() == STRICT) {
     CheckConflictingVarDeclarations(scope, CHECK_OK);
   }
 
-  FunctionLiteral::IsGeneratorFlag generator = is_generator
-      ? FunctionLiteral::kIsGenerator
-      : FunctionLiteral::kNotGenerator;
+  FunctionLiteral::KindFlag kind = is_generator
+      ? FunctionLiteral::kGeneratorFunction
+      : FunctionLiteral::kNormalFunction;
   FunctionLiteral* function_literal =
       factory()->NewFunctionLiteral(function_name,
                                     scope,
                                     body,
                                     materialized_literal_count,
                                     expected_property_count,
                                     handler_count,
                                     num_parameters,
                                     duplicate_parameters,
                                     function_type,
                                     FunctionLiteral::kIsFunction,
                                     parenthesized,
-                                    generator,
+                                    kind,
                                     pos);
   function_literal->set_function_token_position(function_token_pos);
   function_literal->set_ast_properties(&ast_properties);
   function_literal->set_dont_optimize_reason(dont_optimize_reason);
 
   if (fni_ != NULL && should_infer_name) fni_->AddFunction(function_literal);
   return function_literal;
 }
 
 
@@ skipping 141 matching lines @@
 
   if (reusable_preparser_ == NULL) {
     intptr_t stack_limit = isolate()->stack_guard()->real_climit();
     reusable_preparser_ = new PreParser(&scanner_, NULL, stack_limit);
     reusable_preparser_->set_allow_harmony_scoping(allow_harmony_scoping());
     reusable_preparser_->set_allow_modules(allow_modules());
     reusable_preparser_->set_allow_natives_syntax(allow_natives_syntax());
     reusable_preparser_->set_allow_lazy(true);
     reusable_preparser_->set_allow_generators(allow_generators());
     reusable_preparser_->set_allow_for_of(allow_for_of());
+    reusable_preparser_->set_allow_arrow_functions(allow_arrow_functions());
     reusable_preparser_->set_allow_harmony_numeric_literals(
         allow_harmony_numeric_literals());
   }
   PreParser::PreParseResult result =
       reusable_preparser_->PreParseLazyFunction(strict_mode(),
                                                 is_generator(),
                                                 logger);
   return result;
 }
 
@@ skipping 1078 matching lines @@
       ASSERT(info()->isolate()->has_pending_exception());
     } else {
       result = ParseProgram();
     }
   }
   info()->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal