Version 3.7.1

src/parser.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 389 matching lines @@
 unsigned ScriptDataImpl::Read(int position) {
   return store_[PreparseDataConstants::kHeaderSize + position];
 }
 
 
 unsigned* ScriptDataImpl::ReadAddress(int position) {
   return &store_[PreparseDataConstants::kHeaderSize + position];
 }
 
 
-Scope* Parser::NewScope(Scope* parent, Scope::Type type, bool inside_with) {
+Scope* Parser::NewScope(Scope* parent, ScopeType type) {
   Scope* result = new(zone()) Scope(parent, type);
-  result->Initialize(inside_with);
+  result->Initialize();
   return result;
 }
 
 
 // ----------------------------------------------------------------------------
 // Target is a support class to facilitate manipulation of the
 // Parser's target_stack_ (the stack of potential 'break' and
 // 'continue' statement targets). Upon construction, a new target is
 // added; it is removed upon destruction.
 
@@ skipping 29 matching lines @@
     *variable_ = previous_;
   }
 
  private:
   Target** variable_;
   Target* previous_;
 };
 
 
 // ----------------------------------------------------------------------------
-// LexicalScope is a support class to facilitate manipulation of the
-// Parser's scope stack. The constructor sets the parser's top scope
-// to the incoming scope, and the destructor resets it.
-//
-// Additionally, it stores transient information used during parsing.
-// These scopes are not kept around after parsing or referenced by syntax
-// trees so they can be stack-allocated and hence used by the pre-parser.
+// LexicalScope and SaveScope are stack allocated support classes to facilitate
+// anipulation of the Parser's scope stack. The constructor sets the parser's
+// top scope to the incoming scope, and the destructor resets it. Additionally,
+// LexicalScope stores transient information used during parsing.
+
+
+class SaveScope BASE_EMBEDDED {
+ public:
+  SaveScope(Parser* parser, Scope* scope)
+      : parser_(parser),
+        previous_top_scope_(parser->top_scope_) {
+    parser->top_scope_ = scope;
+  }
+
+  ~SaveScope() {
+    parser_->top_scope_ = previous_top_scope_;
+  }
+
+ private:
+  // Bookkeeping
+  Parser* parser_;
+  // Previous values
+  Scope* previous_top_scope_;
+};
+
 
 class LexicalScope BASE_EMBEDDED {
  public:
   LexicalScope(Parser* parser, Scope* scope, Isolate* isolate);
   ~LexicalScope();
 
   int NextMaterializedLiteralIndex() {
     int next_index =
         materialized_literal_count_ + JSFunction::kLiteralsPrefixSize;
     materialized_literal_count_++;
@@ skipping 30 matching lines @@
   // Keeps track of assignments to properties of this. Used for
   // optimizing constructors.
   bool only_simple_this_property_assignments_;
   Handle<FixedArray> this_property_assignments_;
 
   // Bookkeeping
   Parser* parser_;
   // Previous values
   LexicalScope* lexical_scope_parent_;
   Scope* previous_scope_;
-  int previous_with_nesting_level_;
   unsigned previous_ast_node_id_;
 };
 
 
 LexicalScope::LexicalScope(Parser* parser, Scope* scope, Isolate* isolate)
   : materialized_literal_count_(0),
     expected_property_count_(0),
     only_simple_this_property_assignments_(false),
     this_property_assignments_(isolate->factory()->empty_fixed_array()),
     parser_(parser),
     lexical_scope_parent_(parser->lexical_scope_),
     previous_scope_(parser->top_scope_),
-    previous_with_nesting_level_(parser->with_nesting_level_),
     previous_ast_node_id_(isolate->ast_node_id()) {
   parser->top_scope_ = scope;
   parser->lexical_scope_ = this;
-  parser->with_nesting_level_ = 0;
   isolate->set_ast_node_id(AstNode::kDeclarationsId + 1);
 }
 
 
 LexicalScope::~LexicalScope() {
   parser_->top_scope_ = previous_scope_;
   parser_->lexical_scope_ = lexical_scope_parent_;
-  parser_->with_nesting_level_ = previous_with_nesting_level_;
   parser_->isolate()->set_ast_node_id(previous_ast_node_id_);
 }
 
 
 // ----------------------------------------------------------------------------
 // The CHECK_OK macro is a convenient macro to enforce error
 // handling for functions that may fail (by returning !*ok).
 //
 // CAUTION: This macro appends extra statements after a call,
 // thus it must never be used where only a single statement
@@ skipping 16 matching lines @@
 
 Parser::Parser(Handle<Script> script,
                bool allow_natives_syntax,
                v8::Extension* extension,
                ScriptDataImpl* pre_data)
     : isolate_(script->GetIsolate()),
       symbol_cache_(pre_data ? pre_data->symbol_count() : 0),
       script_(script),
       scanner_(isolate_->unicode_cache()),
       top_scope_(NULL),
-      with_nesting_level_(0),
       lexical_scope_(NULL),
       target_stack_(NULL),
       allow_natives_syntax_(allow_natives_syntax),
       extension_(extension),
       pre_data_(pre_data),
       fni_(NULL),
       stack_overflow_(false),
       parenthesized_function_(false),
       harmony_scoping_(false) {
   AstNode::ResetIds();
@@ skipping 24 matching lines @@
     scanner_.Initialize(&stream);
     return DoParseProgram(source, in_global_context, strict_mode, &zone_scope);
   }
 }
 
 
 FunctionLiteral* Parser::DoParseProgram(Handle<String> source,
                                         bool in_global_context,
                                         StrictModeFlag strict_mode,
                                         ZoneScope* zone_scope) {
+  ASSERT(top_scope_ == NULL);
   ASSERT(target_stack_ == NULL);
   if (pre_data_ != NULL) pre_data_->Initialize();
 
   // Compute the parsing mode.
   mode_ = FLAG_lazy ? PARSE_LAZILY : PARSE_EAGERLY;
   if (allow_natives_syntax_ || extension_ != NULL) mode_ = PARSE_EAGERLY;
 
-  Scope::Type type =
-    in_global_context
-      ? Scope::GLOBAL_SCOPE
-      : Scope::EVAL_SCOPE;
+  ScopeType type = in_global_context ? GLOBAL_SCOPE : EVAL_SCOPE;
   Handle<String> no_name = isolate()->factory()->empty_symbol();
 
   FunctionLiteral* result = NULL;
-  { Scope* scope = NewScope(top_scope_, type, inside_with());
+  { Scope* scope = NewScope(top_scope_, type);
+    scope->set_start_position(0);
+    scope->set_end_position(source->length());
     LexicalScope lexical_scope(this, scope, isolate());
-    if (strict_mode == kStrictMode) {
-      top_scope_->EnableStrictMode();
-    }
+    ASSERT(top_scope_->strict_mode_flag() == kNonStrictMode);
+    top_scope_->SetStrictModeFlag(strict_mode);
     ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(16);
     bool ok = true;
     int beg_loc = scanner().location().beg_pos;
     ParseSourceElements(body, Token::EOS, &ok);
     if (ok && top_scope_->is_strict_mode()) {
       CheckOctalLiteral(beg_loc, scanner().location().end_pos, &ok);
     }
 
     if (ok && harmony_scoping_) {
       CheckConflictingVarDeclarations(scope, &ok);
     }
 
     if (ok) {
       result = new(zone()) FunctionLiteral(
           isolate(),
           no_name,
           top_scope_,
           body,
           lexical_scope.materialized_literal_count(),
           lexical_scope.expected_property_count(),
           lexical_scope.only_simple_this_property_assignments(),
           lexical_scope.this_property_assignments(),
           0,
-          0,
-          source->length(),
           FunctionLiteral::ANONYMOUS_EXPRESSION,
           false);  // Does not have duplicate parameters.
     } else if (stack_overflow_) {
       isolate()->StackOverflow();
     }
   }
 
   // Make sure the target stack is empty.
   ASSERT(target_stack_ == NULL);
 
@@ skipping 27 matching lines @@
     return result;
   }
 }
 
 
 FunctionLiteral* Parser::ParseLazy(CompilationInfo* info,
                                    UC16CharacterStream* source,
                                    ZoneScope* zone_scope) {
   Handle<SharedFunctionInfo> shared_info = info->shared_info();
   scanner_.Initialize(source);
+  ASSERT(top_scope_ == NULL);
   ASSERT(target_stack_ == NULL);
 
   Handle<String> name(String::cast(shared_info->name()));
   fni_ = new(zone()) FuncNameInferrer(isolate());
   fni_->PushEnclosingName(name);
 
   mode_ = PARSE_EAGERLY;
 
   // Place holder for the result.
   FunctionLiteral* result = NULL;
 
   {
     // Parse the function literal.
-    Scope* scope = NewScope(top_scope_, Scope::GLOBAL_SCOPE, inside_with());
+    Scope* scope = NewScope(top_scope_, GLOBAL_SCOPE);
     if (!info->closure().is_null()) {
       scope = Scope::DeserializeScopeChain(info, scope);
     }
     LexicalScope lexical_scope(this, scope, isolate());
-
-    if (shared_info->strict_mode()) {
-      top_scope_->EnableStrictMode();
-    }
-
+    ASSERT(scope->strict_mode_flag() == kNonStrictMode ||
+           scope->strict_mode_flag() == info->strict_mode_flag());
+    ASSERT(info->strict_mode_flag() == shared_info->strict_mode_flag());
+    scope->SetStrictModeFlag(shared_info->strict_mode_flag());
     FunctionLiteral::Type type = shared_info->is_expression()
         ? (shared_info->is_anonymous()
               ? FunctionLiteral::ANONYMOUS_EXPRESSION
               : FunctionLiteral::NAMED_EXPRESSION)
         : FunctionLiteral::DECLARATION;
     bool ok = true;
     result = ParseFunctionLiteral(name,
                                   false,  // Strict mode name already checked.
                                   RelocInfo::kNoPosition,
                                   type,
@@ skipping 371 matching lines @@
 Statement* Parser::ParseSourceElement(ZoneStringList* labels,
                                       bool* ok) {
   // (Ecma 262 5th Edition, clause 14):
   // SourceElement:
   //    Statement
   //    FunctionDeclaration
   //
   // In harmony mode we allow additionally the following productions
   // SourceElement:
   //    LetDeclaration
+  //    ConstDeclaration
 
   if (peek() == Token::FUNCTION) {
     return ParseFunctionDeclaration(ok);
-  } else if (peek() == Token::LET) {
+  } else if (peek() == Token::LET || peek() == Token::CONST) {
     return ParseVariableStatement(kSourceElement, ok);
-  } else {
-    return ParseStatement(labels, ok);
   }
+  return ParseStatement(labels, ok);
 }
 
 
 void* Parser::ParseSourceElements(ZoneList<Statement*>* processor,
                                   int end_token,
                                   bool* ok) {
   // SourceElements ::
   //   (SourceElement)* <end_token>
 
   // Allocate a target stack to use for this set of source
@@ skipping 27 matching lines @@
       if ((e_stat = stat->AsExpressionStatement()) != NULL &&
           (literal = e_stat->expression()->AsLiteral()) != NULL &&
           literal->handle()->IsString()) {
         Handle<String> directive = Handle<String>::cast(literal->handle());
 
         // Check "use strict" directive (ES5 14.1).
         if (!top_scope_->is_strict_mode() &&
             directive->Equals(isolate()->heap()->use_strict()) &&
             token_loc.end_pos - token_loc.beg_pos ==
               isolate()->heap()->use_strict()->length() + 2) {
-          top_scope_->EnableStrictMode();
+          top_scope_->SetStrictModeFlag(kStrictMode);
           // "use strict" is the only directive for now.
           directive_prologue = false;
         }
       } else {
         // End of the directive prologue.
         directive_prologue = false;
       }
     }
 
     block_finder.Update(stat);
@@ skipping 117 matching lines @@
     }
 
     case Token::FUNCTION: {
       // FunctionDeclaration is only allowed in the context of SourceElements
       // (Ecma 262 5th Edition, clause 14):
       // SourceElement:
       //    Statement
       //    FunctionDeclaration
       // Common language extension is to allow function declaration in place
       // of any statement. This language extension is disabled in strict mode.
-      if (top_scope_->is_strict_mode()) {
+      if (top_scope_->is_strict_mode() || harmony_scoping_) {
         ReportMessageAt(scanner().peek_location(), "strict_function",
                         Vector<const char*>::empty());
         *ok = false;
         return NULL;
       }
       return ParseFunctionDeclaration(ok);
     }
 
     case Token::DEBUGGER:
       stmt = ParseDebuggerStatement(ok);
@@ skipping 11 matching lines @@
 
 VariableProxy* Parser::Declare(Handle<String> name,
                                VariableMode mode,
                                FunctionLiteral* fun,
                                bool resolve,
                                bool* ok) {
   Variable* var = NULL;
   // If we are inside a function, a declaration of a var/const variable is a
   // truly local variable, and the scope of the variable is always the function
   // scope.
+  // Let/const variables in harmony mode are always added to the immediately
+  // enclosing scope.
+  Scope* declaration_scope = (mode == LET || mode == CONST_HARMONY)
+      ? top_scope_ : top_scope_->DeclarationScope();
 
   // If a function scope exists, then we can statically declare this
   // variable and also set its mode. In any case, a Declaration node
   // will be added to the scope so that the declaration can be added
   // to the corresponding activation frame at runtime if necessary.
   // For instance declarations inside an eval scope need to be added
   // to the calling function context.
   // Similarly, strict mode eval scope does not leak variable declarations to
   // the caller's scope so we declare all locals, too.
-
-  Scope* declaration_scope = mode == LET ? top_scope_
-      : top_scope_->DeclarationScope();
+  // Also for block scoped let/const bindings the variable can be
+  // statically declared.
   if (declaration_scope->is_function_scope() ||
       declaration_scope->is_strict_mode_eval_scope() ||
       declaration_scope->is_block_scope()) {
     // Declare the variable in the function scope.
     var = declaration_scope->LocalLookup(name);
     if (var == NULL) {
       // Declare the name.
       var = declaration_scope->DeclareLocal(name, mode);
     } else {
       // The name was declared in this scope before; check for conflicting
       // re-declarations. We have a conflict if either of the declarations is
       // not a var. There is similar code in runtime.cc in the Declare
       // functions. The function CheckNonConflictingScope checks for conflicting
       // var and let bindings from different scopes whereas this is a check for
       // conflicting declarations within the same scope. This check also covers
       //
       // function () { let x; { var x; } }
       //
       // because the var declaration is hoisted to the function scope where 'x'
       // is already bound.
       if ((mode != VAR) || (var->mode() != VAR)) {
         // We only have vars, consts and lets in declarations.
         ASSERT(var->mode() == VAR ||
                var->mode() == CONST ||
+               var->mode() == CONST_HARMONY ||
                var->mode() == LET);
         if (harmony_scoping_) {
           // In harmony mode we treat re-declarations as early errors. See
           // ES5 16 for a definition of early errors.
           SmartArrayPointer<char> c_string = name->ToCString(DISALLOW_NULLS);
           const char* elms[2] = { "Variable", *c_string };
           Vector<const char*> args(elms, 2);
           ReportMessage("redeclaration", args);
           *ok = false;
           return NULL;
         }
-        const char* type = (var->mode() == VAR) ? "var" :
-                           (var->mode() == CONST) ? "const" : "let";
+        const char* type = (var->mode() == VAR)
+            ? "var" : var->is_const_mode() ? "const" : "let";
         Handle<String> type_string =
             isolate()->factory()->NewStringFromUtf8(CStrVector(type), TENURED);
         Expression* expression =
             NewThrowTypeError(isolate()->factory()->redeclaration_symbol(),
                               type_string, name);
         declaration_scope->SetIllegalRedeclaration(expression);
       }
     }
   }
 
   // We add a declaration node for every declaration. The compiler
   // will only generate code if necessary. In particular, declarations
   // for inner local variables that do not represent functions won't
   // result in any generated code.
   //
   // Note that we always add an unresolved proxy even if it's not
   // used, simply because we don't know in this method (w/o extra
   // parameters) if the proxy is needed or not. The proxy will be
   // bound during variable resolution time unless it was pre-bound
   // below.
   //
   // WARNING: This will lead to multiple declaration nodes for the
   // same variable if it is declared several times. This is not a
   // semantic issue as long as we keep the source order, but it may be
   // a performance issue since it may lead to repeated
   // Runtime::DeclareContextSlot() calls.
   VariableProxy* proxy = declaration_scope->NewUnresolved(
-      name, false, scanner().location().beg_pos);
+      name, scanner().location().beg_pos);
   declaration_scope->AddDeclaration(
       new(zone()) Declaration(proxy, mode, fun, top_scope_));
 
   // For global const variables we bind the proxy to a variable.
-  if (mode == CONST && declaration_scope->is_global_scope()) {
+  if ((mode == CONST || mode == CONST_HARMONY) &&
+      declaration_scope->is_global_scope()) {
     ASSERT(resolve);  // should be set by all callers
     Variable::Kind kind = Variable::NORMAL;
     var = new(zone()) Variable(declaration_scope, name, CONST, true, kind);
   }
 
   // If requested and we have a local variable, bind the proxy to the variable
   // at parse-time. This is used for functions (and consts) declared inside
   // statements: the corresponding function (or const) variable must be in the
   // function scope and not a statement-local scope, e.g. as provided with a
   // 'with' statement:
@@ skipping 127 matching lines @@
 
 
 Block* Parser::ParseScopedBlock(ZoneStringList* labels, bool* ok) {
   // The harmony mode uses source elements instead of statements.
   //
   // Block ::
   //   '{' SourceElement* '}'
 
   // Construct block expecting 16 statements.
   Block* body = new(zone()) Block(isolate(), labels, 16, false);
-  Scope* saved_scope = top_scope_;
-  Scope* block_scope = NewScope(top_scope_,
-                                Scope::BLOCK_SCOPE,
-                                inside_with());
-  if (top_scope_->is_strict_mode()) {
-    block_scope->EnableStrictMode();
-  }
-  top_scope_ = block_scope;
+  Scope* block_scope = NewScope(top_scope_, BLOCK_SCOPE);
 
   // Parse the statements and collect escaping labels.
-  TargetCollector collector;
-  Target target(&this->target_stack_, &collector);
   Expect(Token::LBRACE, CHECK_OK);
-  {
+  block_scope->set_start_position(scanner().location().beg_pos);
+  { SaveScope save_scope(this, block_scope);
+    TargetCollector collector;
+    Target target(&this->target_stack_, &collector);
     Target target_body(&this->target_stack_, body);
     InitializationBlockFinder block_finder(top_scope_, target_stack_);
 
     while (peek() != Token::RBRACE) {
       Statement* stat = ParseSourceElement(NULL, CHECK_OK);
       if (stat && !stat->IsEmpty()) {
         body->AddStatement(stat);
         block_finder.Update(stat);
       }
     }
   }
   Expect(Token::RBRACE, CHECK_OK);
-  top_scope_ = saved_scope;
-
+  block_scope->set_end_position(scanner().location().end_pos);
   block_scope = block_scope->FinalizeBlockScope();
   body->set_block_scope(block_scope);
   return body;
 }
 
 
 Block* Parser::ParseVariableStatement(VariableDeclarationContext var_context,
                                       bool* ok) {
   // VariableStatement ::
   //   VariableDeclarations ';'
 
   Handle<String> ignore;
   Block* result = ParseVariableDeclarations(var_context,
+                                            NULL,
                                             &ignore,
                                             CHECK_OK);
   ExpectSemicolon(CHECK_OK);
   return result;
 }
 
 
 bool Parser::IsEvalOrArguments(Handle<String> string) {
   return string.is_identical_to(isolate()->factory()->eval_symbol()) ||
       string.is_identical_to(isolate()->factory()->arguments_symbol());
 }
 
 
 // If the variable declaration declares exactly one non-const
 // variable, then *var is set to that variable. In all other cases,
 // *var is untouched; in particular, it is the caller's responsibility
 // to initialize it properly. This mechanism is used for the parsing
 // of 'for-in' loops.
-Block* Parser::ParseVariableDeclarations(VariableDeclarationContext var_context,
-                                         Handle<String>* out,
-                                         bool* ok) {
+Block* Parser::ParseVariableDeclarations(
+    VariableDeclarationContext var_context,
+    VariableDeclarationProperties* decl_props,
+    Handle<String>* out,
+    bool* ok) {
   // VariableDeclarations ::
-  //   ('var' | 'const') (Identifier ('=' AssignmentExpression)?)+[',']
-
+  //   ('var' | 'const' | 'let') (Identifier ('=' AssignmentExpression)?)+[',']
+  //
+  // The ES6 Draft Rev3 specifies the following grammar for const declarations
+  //
+  // ConstDeclaration ::
+  //   const ConstBinding (',' ConstBinding)* ';'
+  // ConstBinding ::
+  //   Identifier '=' AssignmentExpression
+  //
+  // TODO(ES6):
+  // ConstBinding ::
+  //   BindingPattern '=' AssignmentExpression
   VariableMode mode = VAR;
   // True if the binding needs initialization. 'let' and 'const' declared
   // bindings are created uninitialized by their declaration nodes and
   // need initialization. 'var' declared bindings are always initialized
   // immediately by their declaration nodes.
   bool needs_init = false;
   bool is_const = false;
   Token::Value init_op = Token::INIT_VAR;
   if (peek() == Token::VAR) {
     Consume(Token::VAR);
   } else if (peek() == Token::CONST) {
     Consume(Token::CONST);
-    if (top_scope_->is_strict_mode()) {
+    if (harmony_scoping_) {
+      if (var_context != kSourceElement &&
+          var_context != kForStatement) {
+        // In harmony mode 'const' declarations are only allowed in source
+        // element positions.
+        ReportMessage("unprotected_const", Vector<const char*>::empty());
+        *ok = false;
+        return NULL;
+      }
+      mode = CONST_HARMONY;
+      init_op = Token::INIT_CONST_HARMONY;
+    } else if (top_scope_->is_strict_mode()) {
       ReportMessage("strict_const", Vector<const char*>::empty());
       *ok = false;
       return NULL;
+    } else {
+      mode = CONST;
+      init_op = Token::INIT_CONST;
     }
-    mode = CONST;
     is_const = true;
     needs_init = true;
-    init_op = Token::INIT_CONST;
   } else if (peek() == Token::LET) {
     Consume(Token::LET);
     if (var_context != kSourceElement &&
         var_context != kForStatement) {
+      // Let declarations are only allowed in source element positions.
       ASSERT(var_context == kStatement);
       ReportMessage("unprotected_let", Vector<const char*>::empty());
       *ok = false;
       return NULL;
     }
     mode = LET;
     needs_init = true;
     init_op = Token::INIT_LET;
   } else {
     UNREACHABLE();  // by current callers
   }
 
-  Scope* declaration_scope = (mode == LET)
+  Scope* declaration_scope = (mode == LET || mode == CONST_HARMONY)
       ? top_scope_ : top_scope_->DeclarationScope();
   // The scope of a var/const declared variable anywhere inside a function
   // is the entire function (ECMA-262, 3rd, 10.1.3, and 12.2). Thus we can
   // transform a source-level var/const declaration into a (Function)
   // Scope declaration, and rewrite the source-level initialization into an
   // assignment statement. We use a block to collect multiple assignments.
   //
   // We mark the block as initializer block because we don't want the
   // rewriter to add a '.result' assignment to such a block (to get compliant
   // behavior for code such as print(eval('var x = 7')), and for cosmetic
@@ skipping 24 matching lines @@
     // assignment for variables and constants because the value must be assigned
     // when the variable is encountered in the source. But the variable/constant
     // is declared (and set to 'undefined') upon entering the function within
     // which the variable or constant is declared. Only function variables have
     // an initial value in the declaration (because they are initialized upon
     // entering the function).
     //
     // If we have a const declaration, in an inner scope, the proxy is always
     // bound to the declared variable (independent of possibly surrounding with
     // statements).
-    Declare(name, mode, NULL, is_const /* always bound for CONST! */,
-            CHECK_OK);
+    // For let/const declarations in harmony mode, we can also immediately
+    // pre-resolve the proxy because it resides in the same scope as the
+    // declaration.
+    Declare(name, mode, NULL, mode != VAR, CHECK_OK);
     nvars++;
     if (declaration_scope->num_var_or_const() > kMaxNumFunctionLocals) {
       ReportMessageAt(scanner().location(), "too_many_variables",
                       Vector<const char*>::empty());
       *ok = false;
       return NULL;
     }
 
     // Parse initialization expression if present and/or needed. A
     // declaration of the form:
@@ skipping 18 matching lines @@
     //
     //   const c; c = x;
     //
     // The "variable" c initialized to x is the same as the declared
     // one - there is no re-lookup (see the last parameter of the
     // Declare() call above).
 
     Scope* initialization_scope = is_const ? declaration_scope : top_scope_;
     Expression* value = NULL;
     int position = -1;
-    if (peek() == Token::ASSIGN) {
+    // Harmony consts have non-optional initializers.
+    if (peek() == Token::ASSIGN || mode == CONST_HARMONY) {
       Expect(Token::ASSIGN, CHECK_OK);
       position = scanner().location().beg_pos;
       value = ParseAssignmentExpression(var_context != kForStatement, CHECK_OK);
       // Don't infer if it is "a = function(){...}();"-like expression.
       if (fni_ != NULL &&
           value->AsCall() == NULL &&
           value->AsCallNew() == NULL) {
         fni_->Infer();
       } else {
         fni_->RemoveLastFunction();
       }
+      if (decl_props != NULL) *decl_props = kHasInitializers;
     }
 
     // Make sure that 'const x' and 'let x' initialize 'x' to undefined.
     if (value == NULL && needs_init) {
       value = GetLiteralUndefined();
     }
 
     // Global variable declarations must be compiled in a specific
     // way. When the script containing the global variable declaration
     // is entered, the global variable must be declared, so that if it
     // doesn't exist (not even in a prototype of the global object) it
     // gets created with an initial undefined value. This is handled
     // by the declarations part of the function representing the
     // top-level global code; see Runtime::DeclareGlobalVariable. If
     // it already exists (in the object or in a prototype), it is
     // *not* touched until the variable declaration statement is
     // executed.
     //
     // Executing the variable declaration statement will always
     // guarantee to give the global object a "local" variable; a
     // variable defined in the global object and not in any
     // prototype. This way, global variable declarations can shadow
     // properties in the prototype chain, but only after the variable
     // declaration statement has been executed. This is important in
     // browsers where the global object (window) has lots of
     // properties defined in prototype objects.
-
     if (initialization_scope->is_global_scope()) {
       // Compute the arguments for the runtime call.
       ZoneList<Expression*>* arguments = new(zone()) ZoneList<Expression*>(3);
       // We have at least 1 parameter.
       arguments->Add(NewLiteral(name));
       CallRuntime* initialize;
 
       if (is_const) {
         arguments->Add(value);
         value = NULL;  // zap the value to avoid the unnecessary assignment
 
         // Construct the call to Runtime_InitializeConstGlobal
         // and add it to the initialization statement block.
         // Note that the function does different things depending on
         // the number of arguments (1 or 2).
         initialize =
             new(zone()) CallRuntime(
                 isolate(),
                 isolate()->factory()->InitializeConstGlobal_symbol(),
                 Runtime::FunctionForId(Runtime::kInitializeConstGlobal),
                 arguments);
       } else {
         // Add strict mode.
         // We may want to pass singleton to avoid Literal allocations.
-        StrictModeFlag flag = initialization_scope->is_strict_mode()
-            ? kStrictMode
-            : kNonStrictMode;
+        StrictModeFlag flag = initialization_scope->strict_mode_flag();
         arguments->Add(NewNumberLiteral(flag));
 
         // Be careful not to assign a value to the global variable if
         // we're in a with. The initialization value should not
         // necessarily be stored in the global object in that case,
         // which is why we need to generate a separate assignment node.
         if (value != NULL && !inside_with()) {
           arguments->Add(value);
           value = NULL;  // zap the value to avoid the unnecessary assignment
         }
@@ skipping 16 matching lines @@
     // Add an assignment node to the initialization statement block if we still
     // have a pending initialization value. We must distinguish between
     // different kinds of declarations: 'var' initializations are simply
     // assignments (with all the consequences if they are inside a 'with'
     // statement - they may change a 'with' object property). Constant
     // initializations always assign to the declared constant which is
     // always at the function scope level. This is only relevant for
     // dynamically looked-up variables and constants (the start context
     // for constant lookups is always the function context, while it is
     // the top context for var declared variables). Sigh...
-    // For 'let' declared variables the initialization is in the same scope
-    // as the declaration. Thus dynamic lookups are unnecessary even if the
-    // block scope is inside a with.
+    // For 'let' and 'const' declared variables in harmony mode the
+    // initialization is in the same scope as the declaration. Thus dynamic
+    // lookups are unnecessary even if the block scope is inside a with.
     if (value != NULL) {
-      bool in_with = (mode == VAR) ? inside_with() : false;
-      VariableProxy* proxy =
-          initialization_scope->NewUnresolved(name, in_with);
+      VariableProxy* proxy = initialization_scope->NewUnresolved(name);
       Assignment* assignment =
           new(zone()) Assignment(isolate(), init_op, proxy, value, position);
-      if (block) {
-        block->AddStatement(new(zone()) ExpressionStatement(assignment));
-      }
+      block->AddStatement(new(zone()) ExpressionStatement(assignment));
     }
 
     if (fni_ != NULL) fni_->Leave();
   } while (peek() == Token::COMMA);
 
   // If there was a single non-const declaration, return it in the output
   // parameter for possible use by for/in.
   if (nvars == 1 && !is_const) {
     *out = name;
   }
@@ skipping 202 matching lines @@
   if (top_scope_->is_strict_mode()) {
     ReportMessage("strict_mode_with", Vector<const char*>::empty());
     *ok = false;
     return NULL;
   }
 
   Expect(Token::LPAREN, CHECK_OK);
   Expression* expr = ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
 
-  ++with_nesting_level_;
   top_scope_->DeclarationScope()->RecordWithStatement();
-  Statement* stmt = ParseStatement(labels, CHECK_OK);
-  --with_nesting_level_;
+  Scope* with_scope = NewScope(top_scope_, WITH_SCOPE);
+  Statement* stmt;
+  { SaveScope save_scope(this, with_scope);
+    with_scope->set_start_position(scanner().peek_location().beg_pos);
+    stmt = ParseStatement(labels, CHECK_OK);
+    with_scope->set_end_position(scanner().location().end_pos);
+  }
   return new(zone()) WithStatement(expr, stmt);
 }
 
 
 CaseClause* Parser::ParseCaseClause(bool* default_seen_ptr, bool* ok) {
   // CaseClause ::
   //   'case' Expression ':' Statement*
   //   'default' ':' Statement*
 
   Expression* label = NULL;  // NULL expression indicates default case
@@ skipping 104 matching lines @@
   // always collect the targets.
   TargetCollector catch_collector;
   Scope* catch_scope = NULL;
   Variable* catch_variable = NULL;
   Block* catch_block = NULL;
   Handle<String> name;
   if (tok == Token::CATCH) {
     Consume(Token::CATCH);
 
     Expect(Token::LPAREN, CHECK_OK);
+    catch_scope = NewScope(top_scope_, CATCH_SCOPE);
+    catch_scope->set_start_position(scanner().location().beg_pos);
     name = ParseIdentifier(CHECK_OK);
 
     if (top_scope_->is_strict_mode() && IsEvalOrArguments(name)) {
       ReportMessage("strict_catch_variable", Vector<const char*>::empty());
       *ok = false;
       return NULL;
     }
 
     Expect(Token::RPAREN, CHECK_OK);
 
     if (peek() == Token::LBRACE) {
       Target target(&this->target_stack_, &catch_collector);
-      catch_scope = NewScope(top_scope_, Scope::CATCH_SCOPE, inside_with());
-      if (top_scope_->is_strict_mode()) {
-        catch_scope->EnableStrictMode();
-      }
       VariableMode mode = harmony_scoping_ ? LET : VAR;
       catch_variable = catch_scope->DeclareLocal(name, mode);
 
-      Scope* saved_scope = top_scope_;
-      top_scope_ = catch_scope;
+      SaveScope save_scope(this, catch_scope);
       catch_block = ParseBlock(NULL, CHECK_OK);
-      top_scope_ = saved_scope;
     } else {
       Expect(Token::LBRACE, CHECK_OK);
     }
-
+    catch_scope->set_end_position(scanner().location().end_pos);
     tok = peek();
   }
 
   Block* finally_block = NULL;
   if (tok == Token::FINALLY || catch_block == NULL) {
     Consume(Token::FINALLY);
     finally_block = ParseBlock(NULL, CHECK_OK);
   }
 
   // Simplify the AST nodes by converting:
@@ skipping 85 matching lines @@
   return loop;
 }
 
 
 Statement* Parser::ParseForStatement(ZoneStringList* labels, bool* ok) {
   // ForStatement ::
   //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement
 
   Statement* init = NULL;
 
+  // Create an in-between scope for let-bound iteration variables.
+  Scope* saved_scope = top_scope_;
+  Scope* for_scope = NewScope(top_scope_, BLOCK_SCOPE);
+  top_scope_ = for_scope;
+
   Expect(Token::FOR, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
+  for_scope->set_start_position(scanner().location().beg_pos);
   if (peek() != Token::SEMICOLON) {
     if (peek() == Token::VAR || peek() == Token::CONST) {
       Handle<String> name;
       Block* variable_statement =
-          ParseVariableDeclarations(kForStatement, &name, CHECK_OK);
+          ParseVariableDeclarations(kForStatement, NULL, &name, CHECK_OK);
 
       if (peek() == Token::IN && !name.is_null()) {
-        VariableProxy* each = top_scope_->NewUnresolved(name, inside_with());
+        VariableProxy* each = top_scope_->NewUnresolved(name);
         ForInStatement* loop = new(zone()) ForInStatement(isolate(), labels);
         Target target(&this->target_stack_, loop);
 
         Expect(Token::IN, CHECK_OK);
         Expression* enumerable = ParseExpression(true, CHECK_OK);
         Expect(Token::RPAREN, CHECK_OK);
 
         Statement* body = ParseStatement(NULL, CHECK_OK);
         loop->Initialize(each, enumerable, body);
         Block* result = new(zone()) Block(isolate(), NULL, 2, false);
         result->AddStatement(variable_statement);
         result->AddStatement(loop);
+        top_scope_ = saved_scope;
+        for_scope->set_end_position(scanner().location().end_pos);
+        for_scope = for_scope->FinalizeBlockScope();
+        ASSERT(for_scope == NULL);
         // Parsed for-in loop w/ variable/const declaration.
         return result;
       } else {
         init = variable_statement;
       }
+    } else if (peek() == Token::LET) {
+      Handle<String> name;
+      VariableDeclarationProperties decl_props = kHasNoInitializers;
+      Block* variable_statement =
+          ParseVariableDeclarations(kForStatement,
+                                    &decl_props,
+                                    &name,
+                                    CHECK_OK);
+      bool accept_IN = !name.is_null() && decl_props != kHasInitializers;
+      if (peek() == Token::IN && accept_IN) {
+        // Rewrite a for-in statement of the form
+        //
+        //   for (let x in e) b
+        //
+        // into
+        //
+        //   <let x' be a temporary variable>
+        //   for (x' in e) {
+        //     let x;
+        //     x = x';
+        //     b;
+        //   }
 
+        // TODO(keuchel): Move the temporary variable to the block scope, after
+        // implementing stack allocated block scoped variables.
+        Variable* temp = top_scope_->DeclarationScope()->NewTemporary(name);
+        VariableProxy* temp_proxy = new(zone()) VariableProxy(isolate(), temp);
+        VariableProxy* each = top_scope_->NewUnresolved(name, inside_with());
+        ForInStatement* loop = new(zone()) ForInStatement(isolate(), labels);
+        Target target(&this->target_stack_, loop);
+
+        Expect(Token::IN, CHECK_OK);
+        Expression* enumerable = ParseExpression(true, CHECK_OK);
+        Expect(Token::RPAREN, CHECK_OK);
+
+        Statement* body = ParseStatement(NULL, CHECK_OK);
+        Block* body_block = new(zone()) Block(isolate(), NULL, 3, false);
+        Assignment* assignment = new(zone()) Assignment(isolate(),
+                                                        Token::ASSIGN,
+                                                        each,
+                                                        temp_proxy,
+                                                        RelocInfo::kNoPosition);
+        Statement* assignment_statement =
+            new(zone()) ExpressionStatement(assignment);
+        body_block->AddStatement(variable_statement);
+        body_block->AddStatement(assignment_statement);
+        body_block->AddStatement(body);
+        loop->Initialize(temp_proxy, enumerable, body_block);
+        top_scope_ = saved_scope;
+        for_scope->set_end_position(scanner().location().end_pos);
+        for_scope = for_scope->FinalizeBlockScope();
+        body_block->set_block_scope(for_scope);
+        // Parsed for-in loop w/ let declaration.
+        return loop;
+
+      } else {
+        init = variable_statement;
+      }
     } else {
       Expression* expression = ParseExpression(false, CHECK_OK);
       if (peek() == Token::IN) {
         // Signal a reference error if the expression is an invalid
         // left-hand side expression.  We could report this as a syntax
         // error here but for compatibility with JSC we choose to report
         // the error at runtime.
         if (expression == NULL || !expression->IsValidLeftHandSide()) {
           Handle<String> type =
               isolate()->factory()->invalid_lhs_in_for_in_symbol();
           expression = NewThrowReferenceError(type);
         }
         ForInStatement* loop = new(zone()) ForInStatement(isolate(), labels);
         Target target(&this->target_stack_, loop);
 
         Expect(Token::IN, CHECK_OK);
         Expression* enumerable = ParseExpression(true, CHECK_OK);
         Expect(Token::RPAREN, CHECK_OK);
 
         Statement* body = ParseStatement(NULL, CHECK_OK);
         if (loop) loop->Initialize(expression, enumerable, body);
+        top_scope_ = saved_scope;
+        for_scope->set_end_position(scanner().location().end_pos);
+        for_scope = for_scope->FinalizeBlockScope();
+        ASSERT(for_scope == NULL);
         // Parsed for-in loop.
         return loop;
 
       } else {
         init = new(zone()) ExpressionStatement(expression);
       }
     }
   }
 
   // Standard 'for' loop
@@ skipping 10 matching lines @@
   Expect(Token::SEMICOLON, CHECK_OK);
 
   Statement* next = NULL;
   if (peek() != Token::RPAREN) {
     Expression* exp = ParseExpression(true, CHECK_OK);
     next = new(zone()) ExpressionStatement(exp);
   }
   Expect(Token::RPAREN, CHECK_OK);
 
   Statement* body = ParseStatement(NULL, CHECK_OK);
-  if (loop) loop->Initialize(init, cond, next, body);
-  return loop;
+  top_scope_ = saved_scope;
+  for_scope->set_end_position(scanner().location().end_pos);
+  for_scope = for_scope->FinalizeBlockScope();
+  if (for_scope != NULL) {
+    // Rewrite a for statement of the form
+    //
+    //   for (let x = i; c; n) b
+    //
+    // into
+    //
+    //   {
+    //     let x = i;
+    //     for (; c; n) b
+    //   }
+    ASSERT(init != NULL);
+    Block* result = new(zone()) Block(isolate(), NULL, 2, false);
+    result->AddStatement(init);
+    result->AddStatement(loop);
+    result->set_block_scope(for_scope);
+    if (loop) loop->Initialize(NULL, cond, next, body);
+    return result;
+  } else {
+    if (loop) loop->Initialize(init, cond, next, body);
+    return loop;
+  }
 }
 
 
 // Precedence = 1
 Expression* Parser::ParseExpression(bool accept_IN, bool* ok) {
   // Expression ::
   //   AssignmentExpression
   //   Expression ',' AssignmentExpression
 
   Expression* result = ParseAssignmentExpression(accept_IN, CHECK_OK);
@@ skipping 599 matching lines @@
     case Token::FALSE_LITERAL:
       Consume(Token::FALSE_LITERAL);
       result = new(zone()) Literal(
           isolate(), isolate()->factory()->false_value());
       break;
 
     case Token::IDENTIFIER:
     case Token::FUTURE_STRICT_RESERVED_WORD: {
       Handle<String> name = ParseIdentifier(CHECK_OK);
       if (fni_ != NULL) fni_->PushVariableName(name);
-      result = top_scope_->NewUnresolved(name,
-                                         inside_with(),
-                                         scanner().location().beg_pos);
+      result = top_scope_->NewUnresolved(name, scanner().location().beg_pos);
       break;
     }
 
     case Token::NUMBER: {
       Consume(Token::NUMBER);
       ASSERT(scanner().is_literal_ascii());
       double value = StringToDouble(isolate()->unicode_cache(),
                                     scanner().literal_ascii_string(),
                                     ALLOW_HEX | ALLOW_OCTALS);
       result = NewNumberLiteral(value);
@@ skipping 96 matching lines @@
     values->Add(elem);
     if (peek() != Token::RBRACK) {
       Expect(Token::COMMA, CHECK_OK);
     }
   }
   Expect(Token::RBRACK, CHECK_OK);
 
   // Update the scope information before the pre-parsing bailout.
   int literal_index = lexical_scope_->NextMaterializedLiteralIndex();
 
-  // Allocate a fixed array with all the literals.
-  Handle<FixedArray> literals =
+  // Allocate a fixed array to hold all the object literals.
+  Handle<FixedArray> object_literals =
       isolate()->factory()->NewFixedArray(values->length(), TENURED);
+  Handle<FixedDoubleArray> double_literals;
+  ElementsKind elements_kind = FAST_SMI_ONLY_ELEMENTS;
 
   // Fill in the literals.
   bool is_simple = true;
   int depth = 1;
   for (int i = 0, n = values->length(); i < n; i++) {
     MaterializedLiteral* m_literal = values->at(i)->AsMaterializedLiteral();
     if (m_literal != NULL && m_literal->depth() + 1 > depth) {
       depth = m_literal->depth() + 1;
     }
     Handle<Object> boilerplate_value = GetBoilerplateValue(values->at(i));
     if (boilerplate_value->IsUndefined()) {
-      literals->set_the_hole(i);
+      object_literals->set_the_hole(i);
+      if (elements_kind == FAST_DOUBLE_ELEMENTS) {
+        double_literals->set_the_hole(i);
+      }
       is_simple = false;
     } else {
-      literals->set(i, *boilerplate_value);
+      // Examine each literal element, and adjust the ElementsKind if the
+      // literal element is not of a type that can be stored in the current
+      // ElementsKind.  Start with FAST_SMI_ONLY_ELEMENTS, and transition to
+      // FAST_DOUBLE_ELEMENTS and FAST_ELEMENTS as necessary.  Always remember
+      // the tagged value, no matter what the ElementsKind is in case we
+      // ultimately end up in FAST_ELEMENTS.
+      object_literals->set(i, *boilerplate_value);
+      if (elements_kind == FAST_SMI_ONLY_ELEMENTS) {
+        // Smi only elements. Notice if a transition to FAST_DOUBLE_ELEMENTS or
+        // FAST_ELEMENTS is required.
+        if (!boilerplate_value->IsSmi()) {
+          if (boilerplate_value->IsNumber() && FLAG_smi_only_arrays) {
+            // Allocate a double array on the FAST_DOUBLE_ELEMENTS transition to
+            // avoid over-allocating in TENURED space.
+            double_literals = isolate()->factory()->NewFixedDoubleArray(
+                values->length(), TENURED);
+            // Copy the contents of the FAST_SMI_ONLY_ELEMENT array to the
+            // FAST_DOUBLE_ELEMENTS array so that they are in sync.
+            for (int j = 0; j < i; ++j) {
+              Object* smi_value = object_literals->get(j);
+              if (smi_value->IsTheHole()) {
+                double_literals->set_the_hole(j);
+              } else {
+                double_literals->set(j, Smi::cast(smi_value)->value());
+              }
+            }
+            double_literals->set(i, boilerplate_value->Number());
+            elements_kind = FAST_DOUBLE_ELEMENTS;
+          } else {
+            elements_kind = FAST_ELEMENTS;
+          }
+        }
+      } else if (elements_kind == FAST_DOUBLE_ELEMENTS) {
+        // Continue to store double values in to FAST_DOUBLE_ELEMENTS arrays
+        // until the first value is seen that can't be stored as a double.
+        if (boilerplate_value->IsNumber()) {
+          double_literals->set(i, boilerplate_value->Number());
+        } else {
+          elements_kind = FAST_ELEMENTS;
+        }
+      }
     }
   }
 
   // Simple and shallow arrays can be lazily copied, we transform the
   // elements array to a copy-on-write array.
-  if (is_simple && depth == 1 && values->length() > 0) {
-    literals->set_map(isolate()->heap()->fixed_cow_array_map());
+  if (is_simple && depth == 1 && values->length() > 0 &&
+      elements_kind != FAST_DOUBLE_ELEMENTS) {
+    object_literals->set_map(isolate()->heap()->fixed_cow_array_map());
   }
 
+  Handle<FixedArrayBase> element_values = elements_kind == FAST_DOUBLE_ELEMENTS
+      ? Handle<FixedArrayBase>(double_literals)
+      : Handle<FixedArrayBase>(object_literals);
+
+  // Remember both the literal's constant values as well as the ElementsKind
+  // in a 2-element FixedArray.
+  Handle<FixedArray> literals =
+      isolate()->factory()->NewFixedArray(2, TENURED);
+
+  literals->set(0, Smi::FromInt(elements_kind));
+  literals->set(1, *element_values);
+
   return new(zone()) ArrayLiteral(
       isolate(), literals, values, literal_index, is_simple, depth);
 }
 
 
 bool Parser::IsBoilerplateProperty(ObjectLiteral::Property* property) {
   return property != NULL &&
          property->kind() != ObjectLiteral::Property::PROTOTYPE;
 }
 
@@ skipping 484 matching lines @@
   // We want a non-null handle as the function name.
   if (should_infer_name) {
     function_name = isolate()->factory()->empty_symbol();
   }
 
   int num_parameters = 0;
   // Function declarations are function scoped in normal mode, so they are
   // hoisted. In harmony block scoping mode they are block scoped, so they
   // are not hoisted.
   Scope* scope = (type == FunctionLiteral::DECLARATION && !harmony_scoping_)
-      ? NewScope(top_scope_->DeclarationScope(), Scope::FUNCTION_SCOPE, false)
-      : NewScope(top_scope_, Scope::FUNCTION_SCOPE, inside_with());
+      ? NewScope(top_scope_->DeclarationScope(), FUNCTION_SCOPE)
+      : NewScope(top_scope_, FUNCTION_SCOPE);
   ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(8);
   int materialized_literal_count;
   int expected_property_count;
-  int start_pos;
-  int end_pos;
   bool only_simple_this_property_assignments;
   Handle<FixedArray> this_property_assignments;
   bool has_duplicate_parameters = false;
   // Parse function body.
   { LexicalScope lexical_scope(this, scope, isolate());
     top_scope_->SetScopeName(function_name);
 
     //  FormalParameterList ::
     //    '(' (Identifier)*[','] ')'
     Expect(Token::LPAREN, CHECK_OK);
-    start_pos = scanner().location().beg_pos;
+    scope->set_start_position(scanner().location().beg_pos);
     Scanner::Location name_loc = Scanner::Location::invalid();
     Scanner::Location dupe_loc = Scanner::Location::invalid();
     Scanner::Location reserved_loc = Scanner::Location::invalid();
 
     bool done = (peek() == Token::RPAREN);
     while (!done) {
       bool is_strict_reserved = false;
       Handle<String> param_name =
           ParseIdentifierOrStrictReservedWord(&is_strict_reserved,
                                               CHECK_OK);
@@ skipping 25 matching lines @@
 
     Expect(Token::LBRACE, CHECK_OK);
 
     // If we have a named function expression, we add a local variable
     // declaration to the body of the function with the name of the
     // function and let it refer to the function itself (closure).
     // NOTE: We create a proxy and resolve it here so that in the
     // future we can change the AST to only refer to VariableProxies
     // instead of Variables and Proxis as is the case now.
     if (type == FunctionLiteral::NAMED_EXPRESSION) {
-      Variable* fvar = top_scope_->DeclareFunctionVar(function_name);
-      VariableProxy* fproxy =
-          top_scope_->NewUnresolved(function_name, inside_with());
+      VariableMode fvar_mode;
+      Token::Value fvar_init_op;
+      if (harmony_scoping_) {
+        fvar_mode = CONST_HARMONY;
+        fvar_init_op = Token::INIT_CONST_HARMONY;
+      } else {
+        fvar_mode = CONST;
+        fvar_init_op = Token::INIT_CONST;
+      }
+      Variable* fvar = top_scope_->DeclareFunctionVar(function_name, fvar_mode);
+      VariableProxy* fproxy = top_scope_->NewUnresolved(function_name);
       fproxy->BindTo(fvar);
       body->Add(new(zone()) ExpressionStatement(
           new(zone()) Assignment(isolate(),
-                                 Token::INIT_CONST,
+                                 fvar_init_op,
                                  fproxy,
                                  new(zone()) ThisFunction(isolate()),
                                  RelocInfo::kNoPosition)));
     }
 
     // Determine if the function will be lazily compiled. The mode can only
     // be PARSE_LAZILY if the --lazy flag is true.  We will not lazily
     // compile if we do not have preparser data for the function.
     bool is_lazily_compiled = (mode() == PARSE_LAZILY &&
                                top_scope_->outer_scope()->is_global_scope() &&
                                top_scope_->HasTrivialOuterContext() &&
                                !parenthesized_function_ &&
                                pre_data() != NULL);
     parenthesized_function_ = false;  // The bit was set for this function only.
 
     if (is_lazily_compiled) {
       int function_block_pos = scanner().location().beg_pos;
       FunctionEntry entry = pre_data()->GetFunctionEntry(function_block_pos);
       if (!entry.is_valid()) {
         // There is no preparser data for the function, we will not lazily
         // compile after all.
         is_lazily_compiled = false;
       } else {
-        end_pos = entry.end_pos();
-        if (end_pos <= function_block_pos) {
+        scope->set_end_position(entry.end_pos());
+        if (scope->end_position() <= function_block_pos) {
           // End position greater than end of stream is safe, and hard to check.
           ReportInvalidPreparseData(function_name, CHECK_OK);
         }
         isolate()->counters()->total_preparse_skipped()->Increment(
-            end_pos - function_block_pos);
+            scope->end_position() - function_block_pos);
         // Seek to position just before terminal '}'.
-        scanner().SeekForward(end_pos - 1);
+        scanner().SeekForward(scope->end_position() - 1);
         materialized_literal_count = entry.literal_count();
         expected_property_count = entry.property_count();
-        if (entry.strict_mode()) top_scope_->EnableStrictMode();
+        if (entry.strict_mode()) top_scope_->SetStrictModeFlag(kStrictMode);
         only_simple_this_property_assignments = false;
         this_property_assignments = isolate()->factory()->empty_fixed_array();
         Expect(Token::RBRACE, CHECK_OK);
       }
     }
 
     if (!is_lazily_compiled) {
       ParseSourceElements(body, Token::RBRACE, CHECK_OK);
 
       materialized_literal_count = lexical_scope.materialized_literal_count();
       expected_property_count = lexical_scope.expected_property_count();
       only_simple_this_property_assignments =
           lexical_scope.only_simple_this_property_assignments();
       this_property_assignments = lexical_scope.this_property_assignments();
 
       Expect(Token::RBRACE, CHECK_OK);
-      end_pos = scanner().location().end_pos;
+      scope->set_end_position(scanner().location().end_pos);
     }
 
     // Validate strict mode.
     if (top_scope_->is_strict_mode()) {
       if (IsEvalOrArguments(function_name)) {
+        int start_pos = scope->start_position();
         int position = function_token_position != RelocInfo::kNoPosition
             ? function_token_position
             : (start_pos > 0 ? start_pos - 1 : start_pos);
         Scanner::Location location = Scanner::Location(position, start_pos);
         ReportMessageAt(location,
                         "strict_function_name", Vector<const char*>::empty());
         *ok = false;
         return NULL;
       }
       if (name_loc.IsValid()) {
         ReportMessageAt(name_loc, "strict_param_name",
                         Vector<const char*>::empty());
         *ok = false;
         return NULL;
       }
       if (dupe_loc.IsValid()) {
         ReportMessageAt(dupe_loc, "strict_param_dupe",
                         Vector<const char*>::empty());
         *ok = false;
         return NULL;
       }
       if (name_is_strict_reserved) {
+        int start_pos = scope->start_position();
         int position = function_token_position != RelocInfo::kNoPosition
             ? function_token_position
             : (start_pos > 0 ? start_pos - 1 : start_pos);
         Scanner::Location location = Scanner::Location(position, start_pos);
         ReportMessageAt(location, "strict_reserved_word",
                         Vector<const char*>::empty());
         *ok = false;
         return NULL;
       }
       if (reserved_loc.IsValid()) {
         ReportMessageAt(reserved_loc, "strict_reserved_word",
                         Vector<const char*>::empty());
         *ok = false;
         return NULL;
       }
-      CheckOctalLiteral(start_pos, end_pos, CHECK_OK);
+      CheckOctalLiteral(scope->start_position(),
+                        scope->end_position(),
+                        CHECK_OK);
     }
   }
 
   if (harmony_scoping_) {
     CheckConflictingVarDeclarations(scope, CHECK_OK);
   }
 
   FunctionLiteral* function_literal =
       new(zone()) FunctionLiteral(isolate(),
                                   function_name,
                                   scope,
                                   body,
                                   materialized_literal_count,
                                   expected_property_count,
                                   only_simple_this_property_assignments,
                                   this_property_assignments,
                                   num_parameters,
-                                  start_pos,
-                                  end_pos,
                                   type,
                                   has_duplicate_parameters);
   function_literal->set_function_token_position(function_token_position);
 
   if (fni_ != NULL && should_infer_name) fni_->AddFunction(function_literal);
   return function_literal;
 }
 
 
 Expression* Parser::ParseV8Intrinsic(bool* ok) {
@@ skipping 1200 matching lines @@
     result = (result << 7) | (input & 0x7f);
     data++;
   }
   *source = data;
   return result;
 }
 
 
 // Create a Scanner for the preparser to use as input, and preparse the source.
 static ScriptDataImpl* DoPreParse(UC16CharacterStream* source,
-                                  bool allow_lazy,
-                                  ParserRecorder* recorder,
-                                  bool harmony_scoping) {
+                                  int flags,
+                                  ParserRecorder* recorder) {
   Isolate* isolate = Isolate::Current();
   JavaScriptScanner scanner(isolate->unicode_cache());
-  scanner.SetHarmonyScoping(harmony_scoping);
+  scanner.SetHarmonyScoping((flags & kHarmonyScoping) != 0);
   scanner.Initialize(source);
   intptr_t stack_limit = isolate->stack_guard()->real_climit();
   if (!preparser::PreParser::PreParseProgram(&scanner,
                                              recorder,
-                                             allow_lazy,
+                                             flags,
                                              stack_limit)) {
     isolate->StackOverflow();
     return NULL;
   }
 
   // Extract the accumulated data from the recorder as a single
   // contiguous vector that we are responsible for disposing.
   Vector<unsigned> store = recorder->ExtractData();
   return new ScriptDataImpl(store);
 }
 
 
 // Preparse, but only collect data that is immediately useful,
 // even if the preparser data is only used once.
 ScriptDataImpl* ParserApi::PartialPreParse(UC16CharacterStream* source,
                                            v8::Extension* extension,
-                                           bool harmony_scoping) {
+                                           int flags) {
   bool allow_lazy = FLAG_lazy && (extension == NULL);
   if (!allow_lazy) {
     // Partial preparsing is only about lazily compiled functions.
     // If we don't allow lazy compilation, the log data will be empty.
     return NULL;
   }
+  flags |= kAllowLazy;
   PartialParserRecorder recorder;
-  return DoPreParse(source, allow_lazy, &recorder, harmony_scoping);
+  return DoPreParse(source, flags, &recorder);
 }
 
 
 ScriptDataImpl* ParserApi::PreParse(UC16CharacterStream* source,
                                     v8::Extension* extension,
-                                    bool harmony_scoping) {
+                                    int flags) {
   Handle<Script> no_script;
-  bool allow_lazy = FLAG_lazy && (extension == NULL);
+  if (FLAG_lazy && (extension == NULL)) {
+    flags |= kAllowLazy;
+  }
   CompleteParserRecorder recorder;
-  return DoPreParse(source, allow_lazy, &recorder, harmony_scoping);
+  return DoPreParse(source, flags, &recorder);
 }
 
 
 bool RegExpParser::ParseRegExp(FlatStringReader* input,
                                bool multiline,
                                RegExpCompileData* result) {
   ASSERT(result != NULL);
   RegExpParser parser(input, &result->error, multiline);
   RegExpTree* tree = parser.ParsePattern();
   if (parser.failed()) {
@@ skipping 42 matching lines @@
       DeleteArray(message);
       for (int i = 0; i < args.length(); i++) {
         DeleteArray(args[i]);
       }
       DeleteArray(args.start());
       ASSERT(info->isolate()->has_pending_exception());
     } else {
       Handle<String> source = Handle<String>(String::cast(script->source()));
       result = parser.ParseProgram(source,
                                    info->is_global(),
-                                   info->StrictMode());
+                                   info->strict_mode_flag());
     }
   }
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal