Introduce with scope and rework variable resolution.

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, Scope::Type 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_block_scoping_(false) {
   AstNode::ResetIds();
@@ skipping 38 matching lines @@
   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;
   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);
     LexicalScope lexical_scope(this, scope, isolate());
     if (strict_mode == kStrictMode) {
       top_scope_->EnableStrictMode();
     }
     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);
@@ skipping 69 matching lines @@
   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_, 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();
     }
 
     FunctionLiteral::Type type = shared_info->is_expression()
@@ skipping 657 matching lines @@
   // 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 == Variable::CONST && 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,
                                Variable::CONST,
@@ skipping 131 matching lines @@
     }
   }
   Expect(Token::RBRACE, CHECK_OK);
   return result;
 }
 
 
 Block* Parser::ParseScopedBlock(ZoneStringList* labels, bool* ok) {
   // 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());
+  Scope* block_scope = NewScope(top_scope_, Scope::BLOCK_SCOPE);
   if (top_scope_->is_strict_mode()) {
     block_scope->EnableStrictMode();
   }
-  top_scope_ = block_scope;
 
   // Parse the statements and collect escaping labels.
-  TargetCollector collector;
-  Target target(&this->target_stack_, &collector);
   Expect(Token::LBRACE, CHECK_OK);
-  {
+  { 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 = block_scope->FinalizeBlockScope();
   body->set_block_scope(block_scope);
   return body;
 }
 
 
 Block* Parser::ParseVariableStatement(VariableDeclarationContext var_context,
                                       bool* ok) {
   // VariableStatement ::
@@ skipping 474 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_, Scope::WITH_SCOPE);
+  Statement* stmt;
+  { SaveScope save_scope(this, with_scope);
+    stmt = ParseStatement(labels, CHECK_OK);
+  }
   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 116 matching lines @@
     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());
+      catch_scope = NewScope(top_scope_, Scope::CATCH_SCOPE);
       if (top_scope_->is_strict_mode()) {
         catch_scope->EnableStrictMode();
       }
       Variable::Mode mode = harmony_block_scoping_
           ? Variable::LET : Variable::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);
     }
 
     tok = peek();
   }
 
   Block* finally_block = NULL;
   if (tok == Token::FINALLY || catch_block == NULL) {
     Consume(Token::FINALLY);
@@ skipping 98 matching lines @@
 
   Expect(Token::FOR, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   if (peek() != Token::SEMICOLON) {
     if (peek() == Token::VAR || peek() == Token::CONST) {
       Handle<String> name;
       Block* variable_statement =
           ParseVariableDeclarations(kForStatement, &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);
@@ skipping 689 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 628 matching lines @@
   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_block_scoping_)
-      ? NewScope(top_scope_->DeclarationScope(), Scope::FUNCTION_SCOPE, false)
-      : NewScope(top_scope_, Scope::FUNCTION_SCOPE, inside_with());
+      ? NewScope(top_scope_->DeclarationScope(), Scope::FUNCTION_SCOPE)
+      : NewScope(top_scope_, 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());
@@ skipping 45 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());
+      VariableProxy* fproxy = top_scope_->NewUnresolved(function_name);
       fproxy->BindTo(fvar);
       body->Add(new(zone()) ExpressionStatement(
           new(zone()) Assignment(isolate(),
                                  Token::INIT_CONST,
                                  fproxy,
                                  new(zone()) ThisFunction(isolate()),
                                  RelocInfo::kNoPosition)));
     }
 
     // Determine if the function will be lazily compiled. The mode can only
@@ skipping 1432 matching lines @@
       result = parser.ParseProgram(source,
                                    info->is_global(),
                                    info->StrictMode());
     }
   }
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal