Avoid temporary Vectors for arrow function parameter lists

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 3254 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 CheckAndCollectArrowParameter(ParserTraits* traits,
-                                   Collector<VariableProxy*>* collector,
-                                   Expression* expression) {
+bool CheckAndDeclareArrowParameter(ParserTraits* traits, Expression* expression,
+                                   Scope* scope, unsigned* 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;
 
-    collector->Add(expression->AsVariableProxy());
+    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 CheckAndCollectArrowParameter(traits, collector, binop->left()) &&
-           CheckAndCollectArrowParameter(traits, collector, binop->right());
+    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;
 }
 
 
-Vector<VariableProxy*> ParserTraits::ParameterListFromExpression(
-    Expression* expression, bool* ok) {
-  Collector<VariableProxy*> collector;
-  *ok = CheckAndCollectArrowParameter(this, &collector, expression);
-  return collector.ToVector();
+unsigned ParserTraits::DeclareArrowParametersFromExpression(
+    Expression* expression, Scope* scope, Scanner::Location* dupe_loc,
+    bool* ok) {
+  unsigned 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,
@@ skipping 1462 matching lines @@
     info()->SetAstValueFactory(ast_value_factory_);
   }
   ast_value_factory_ = NULL;
 
   InternalizeUseCounts();
 
   return (result != NULL);
 }
 
 } }  // namespace v8::internal