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 "src/v8.h"
 
 #include "src/api.h"
 #include "src/ast.h"
 #include "src/base/platform/platform.h"
 #include "src/bootstrapper.h"
@@ skipping 700 matching lines @@
       pending_error_arg_(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);
   for (int feature = 0; feature < v8::Isolate::kUseCounterFeatureCount;
        ++feature) {
     use_counts_[feature] = 0;
   }
 }
 
 
 FunctionLiteral* Parser::ParseProgram() {
   // TODO(bmeurer): We temporarily need to pass allow_nesting = true here,
@@ skipping 2533 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)));
 }
 
 
+bool CheckAndDeclareArrowParameter(ParserTraits* traits, Expression* expression,
+                                   Scope* scope, int* num_params,
+                                   Scanner::Location* dupe_loc) {
+  // Case for empty parameter lists:
+  //   () => ...
+  if (expression == NULL) return true;
+
+  // Too many parentheses around expression:
+  //   (( ... )) => ...
+  if (expression->parenthesization_level() > 1) return false;
+
+  // Case for a single parameter:
+  //   (foo) => ...
+  //   foo => ...
+  if (expression->IsVariableProxy()) {
+    if (expression->AsVariableProxy()->is_this()) return false;
+
+    const AstRawString* raw_name = expression->AsVariableProxy()->raw_name();
+    if (traits->IsEvalOrArguments(raw_name) ||
+        traits->IsFutureStrictReserved(raw_name))
+      return false;
+
+    if (scope->IsDeclared(raw_name)) {
+      *dupe_loc = Scanner::Location(
+          expression->position(), expression->position() + raw_name->length());
+      return false;
+    }
+
+    scope->DeclareParameter(raw_name, VAR);
+    ++(*num_params);
+    return true;
+  }
+
+  // Case for more than one parameter:
+  //   (foo, bar [, ...]) => ...
+  if (expression->IsBinaryOperation()) {
+    BinaryOperation* binop = expression->AsBinaryOperation();
+    if (binop->op() != Token::COMMA || binop->left()->is_parenthesized() ||
+        binop->right()->is_parenthesized())
+      return false;
+
+    return CheckAndDeclareArrowParameter(traits, binop->left(), scope,
+                                         num_params, dupe_loc) &&
+           CheckAndDeclareArrowParameter(traits, binop->right(), scope,
+                                         num_params, dupe_loc);
+  }
+
+  // Any other kind of expression is not a valid parameter list.
+  return false;
+}
+
+
+int ParserTraits::DeclareArrowParametersFromExpression(
+    Expression* expression, Scope* scope, Scanner::Location* dupe_loc,
+    bool* ok) {
+  int num_params = 0;
+  *ok = CheckAndDeclareArrowParameter(this, expression, scope, &num_params,
+                                      dupe_loc);
+  return num_params;
+}
+
+
 FunctionLiteral* Parser::ParseFunctionLiteral(
     const AstRawString* function_name,
     Scanner::Location function_name_location,
     bool name_is_strict_reserved,
     bool is_generator,
     int function_token_pos,
     FunctionLiteral::FunctionType function_type,
     FunctionLiteral::ArityRestriction arity_restriction,
     bool* ok) {
   // Function ::
@@ skipping 389 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 1049 matching lines @@
     info()->SetAstValueFactory(ast_value_factory_);
   }
   ast_value_factory_ = NULL;
 
   InternalizeUseCounts();
 
   return (result != NULL);
 }
 
 } }  // namespace v8::internal