Introduce with scope and rework variable resolution.

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index e8d18106165515f7e43e58ba700d5fcf5d63a4cd..14727ca5970fc161081d073fe1d1d8d79b3826e3 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -407,9 +407,9 @@ unsigned* ScriptDataImpl::ReadAddress(int 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;
 }
 
@@ -459,13 +459,34 @@ class TargetScope BASE_EMBEDDED {
 
 
 // ----------------------------------------------------------------------------
-// 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.
+// LexicalScope and SaveScope are support classes 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.
+// Additionally, LexicalScope stores transient information used during parsing.
+// These scopes are not kept around after parsing or referenced by syntax trees

[Kevin Millikin (Chromium), 2011/09/16 12:58:19]

Does the preparser still use these guys?  If not we should get rid of that part
of the comment.

[Steven, 2011/09/16 18:29:52]

There is PreParser::Scope that remotely corresponds to LexicalScope, but these
classes are unrelated in terms of their implementation, so the preparser doesn't
need to be mentioned here.
Moreover the only important piece of information is the stack-allocation. I will
keep that and remove the rest.
On 2011/09/16 12:58:19, Kevin Millikin wrote:

+// so they can be stack-allocated and hence used by the pre-parser.
+
+
+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:
@@ -516,7 +537,6 @@ class LexicalScope BASE_EMBEDDED {
   // Previous values
   LexicalScope* lexical_scope_parent_;
   Scope* previous_scope_;
-  int previous_with_nesting_level_;
   unsigned previous_ast_node_id_;
 };
 
@@ -529,11 +549,9 @@ LexicalScope::LexicalScope(Parser* parser, Scope* scope, Isolate* isolate)
     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);
 }
 
@@ -541,7 +559,6 @@ LexicalScope::LexicalScope(Parser* parser, Scope* scope, Isolate* isolate)
 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_);
 }
 
@@ -578,7 +595,6 @@ Parser::Parser(Handle<Script> script,
       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),
@@ -637,7 +653,7 @@ FunctionLiteral* Parser::DoParseProgram(Handle<String> source,
   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();
@@ -727,7 +743,7 @@ FunctionLiteral* Parser::ParseLazy(CompilationInfo* info,
 
   {
     // 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);
     }
@@ -1405,7 +1421,7 @@ VariableProxy* Parser::Declare(Handle<String> name,
   // 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_));
 
@@ -1557,20 +1573,16 @@ Block* Parser::ParseBlock(ZoneStringList* labels, bool* ok) {
 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_);
 
@@ -1583,7 +1595,6 @@ Block* Parser::ParseScopedBlock(ZoneStringList* labels, bool* ok) {
     }
   }
   Expect(Token::RBRACE, CHECK_OK);
-  top_scope_ = saved_scope;
 
   block_scope = block_scope->FinalizeBlockScope();
   body->set_block_scope(block_scope);
@@ -2078,10 +2089,12 @@ Statement* Parser::ParseWithStatement(ZoneStringList* labels, bool* 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);
 }
 
@@ -2218,7 +2231,7 @@ TryStatement* Parser::ParseTryStatement(bool* 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();
       }
@@ -2226,10 +2239,8 @@ TryStatement* Parser::ParseTryStatement(bool* ok) {
           ? 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);
     }
@@ -2348,7 +2359,7 @@ Statement* Parser::ParseForStatement(ZoneStringList* labels, bool* ok) {
           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);
 
@@ -3058,9 +3069,7 @@ Expression* Parser::ParsePrimaryExpression(bool* ok) {
     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;
     }
 
@@ -3709,8 +3718,8 @@ FunctionLiteral* Parser::ParseFunctionLiteral(Handle<String> function_name,
   // 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;
@@ -3776,8 +3785,7 @@ FunctionLiteral* Parser::ParseFunctionLiteral(Handle<String> function_name,
     // 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(),