[es6] implement default/optional parameters (WIP / comments)

src/ast.h

Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index 7bfa02178faabb6e09af3c3f8d8f303393da88d1..86b60cb97caf5cb59746bd4e505a2bb7833c4b41 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -1348,6 +1348,7 @@ class Literal FINAL : public Expression {
 
   Handle<Object> value() const { return value_->value(); }
   const AstValue* raw_value() const { return value_; }
+  bool IsUndefined() const { return value_->IsUndefined(); }
 
   // Support for using Literal as a HashMap key. NOTE: Currently, this works
   // only for string and number literals!
@@ -2505,6 +2506,7 @@ class FunctionLiteral FINAL : public Expression {
   const AstRawString* raw_name() const { return raw_name_; }
   Scope* scope() const { return scope_; }
   ZoneList<Statement*>* body() const { return body_; }
+  ZoneList<Expression*>* default_values() const { return default_values_; }

[arv (Not doing code reviews), 2015/04/10 15:08:48]

I'm not sure we want a parallel list for this. It might be tempting to do that
for now but eventually we need to move away from this and store BindingElements
(which may or may not have an initializer).

[caitp (gmail), 2015/04/10 15:28:00]

I agree with you, see other comment. It's a quick hack for now, since I'm not
sure how much code needs to be fixed that is just expecting VariableProxy
expressions

   void set_function_token_position(int pos) { function_token_position_ = pos; }
   int function_token_position() const { return function_token_position_; }
   int start_position() const;
@@ -2609,7 +2611,8 @@ class FunctionLiteral FINAL : public Expression {
                   AstValueFactory* ast_value_factory, Scope* scope,
                   ZoneList<Statement*>* body, int materialized_literal_count,
                   int expected_property_count, int handler_count,
-                  int parameter_count, FunctionType function_type,
+                  int parameter_count, ZoneList<Expression*>* default_values,
+                  FunctionType function_type,
                   ParameterFlag has_duplicate_parameters,
                   IsFunctionFlag is_function,
                   IsParenthesizedFlag is_parenthesized, FunctionKind kind,
@@ -2625,6 +2628,7 @@ class FunctionLiteral FINAL : public Expression {
         expected_property_count_(expected_property_count),
         handler_count_(handler_count),
         parameter_count_(parameter_count),
+        default_values_(default_values),
         function_token_position_(RelocInfo::kNoPosition) {
     bitfield_ = IsExpression::encode(function_type != DECLARATION) |
                 IsAnonymous::encode(function_type == ANONYMOUS_EXPRESSION) |
@@ -2651,6 +2655,7 @@ class FunctionLiteral FINAL : public Expression {
   int expected_property_count_;
   int handler_count_;
   int parameter_count_;
+  ZoneList<Expression*>* default_values_;
   int function_token_position_;
 
   unsigned bitfield_;
@@ -3539,6 +3544,7 @@ class AstNodeFactory FINAL BASE_EMBEDDED {
       const AstRawString* name, AstValueFactory* ast_value_factory,
       Scope* scope, ZoneList<Statement*>* body, int materialized_literal_count,
       int expected_property_count, int handler_count, int parameter_count,
+      ZoneList<Expression*>* default_parameters,
       FunctionLiteral::ParameterFlag has_duplicate_parameters,
       FunctionLiteral::FunctionType function_type,
       FunctionLiteral::IsFunctionFlag is_function,
@@ -3546,9 +3552,9 @@ class AstNodeFactory FINAL BASE_EMBEDDED {
       int position) {
     return new (zone_) FunctionLiteral(
         zone_, name, ast_value_factory, scope, body, materialized_literal_count,
-        expected_property_count, handler_count, parameter_count, function_type,
-        has_duplicate_parameters, is_function, is_parenthesized, kind,
-        position);
+        expected_property_count, handler_count, parameter_count,
+        default_parameters, function_type, has_duplicate_parameters,
+        is_function, is_parenthesized, kind, position);
   }
 
   ClassLiteral* NewClassLiteral(const AstRawString* name, Scope* scope,