Refactor parser Checkpoints.

src/preparser.h

 // 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.
 
 #ifndef V8_PREPARSER_H
 #define V8_PREPARSER_H
 
 #include "src/v8.h"
 
 #include "src/func-name-inferrer.h"
@@ skipping 99 matching lines @@
     scanner()->SetHarmonyScoping(allow);
   }
   void set_allow_harmony_numeric_literals(bool allow) {
     scanner()->SetHarmonyNumericLiterals(allow);
   }
   void set_allow_classes(bool allow) {
     scanner()->SetHarmonyClasses(allow);
   }
 
  protected:
-  friend class Traits::Type::Checkpoint;
+  friend class Traits::Checkpoint;
 
   enum AllowEvalOrArgumentsAsIdentifier {
     kAllowEvalOrArguments,
     kDontAllowEvalOrArguments
   };
 
   enum Mode {
     PARSE_LAZILY,
     PARSE_EAGERLY
   };
 
-  class ParserCheckpoint;
+  class CheckpointBase;
 
   // ---------------------------------------------------------------------------
   // FunctionState and BlockState together implement the parser's scope stack.
   // The parser's current scope is in scope_. BlockState and FunctionState
   // constructors push on the scope stack and the destructors pop. They are also
   // used to hold the parser's per-function and per-block state.
   class BlockState BASE_EMBEDDED {
    public:
     BlockState(typename Traits::Type::Scope** scope_stack,
                typename Traits::Type::Scope* scope)
@@ skipping 76 matching lines @@
 
     FunctionState** function_state_stack_;
     FunctionState* outer_function_state_;
     typename Traits::Type::Scope** scope_stack_;
     typename Traits::Type::Scope* outer_scope_;
     int saved_ast_node_id_;  // Only used by ParserTraits.
     typename Traits::Type::Zone* extra_param_;
     typename Traits::Type::Factory factory_;
 
     friend class ParserTraits;
-    friend class ParserCheckpoint;
+    friend class CheckpointBase;
   };
 
   // Annoyingly, arrow functions first parse as comma expressions, then when we
   // see the => we have to go back and reinterpret the arguments as being formal
   // parameters.  To do so we need to reset some of the parser state back to
   // what it was before the arguments were first seen.
-  class ParserCheckpoint : public Traits::Type::Checkpoint {
+  class CheckpointBase BASE_EMBEDDED {
    public:
-    template <typename Parser>
-    explicit ParserCheckpoint(Parser* parser)
-        : Traits::Type::Checkpoint(parser) {
+    explicit CheckpointBase(ParserBase* parser) {
       function_state_ = parser->function_state_;
       next_materialized_literal_index_ =
           function_state_->next_materialized_literal_index_;
       next_handler_index_ = function_state_->next_handler_index_;
       expected_property_count_ = function_state_->expected_property_count_;
     }
 
     void Restore() {
-      Traits::Type::Checkpoint::Restore();
       function_state_->next_materialized_literal_index_ =
           next_materialized_literal_index_;
       function_state_->next_handler_index_ = next_handler_index_;
       function_state_->expected_property_count_ = expected_property_count_;
     }
 
    private:
     FunctionState* function_state_;
     int next_materialized_literal_index_;
     int next_handler_index_;
@@ skipping 757 matching lines @@
  public:
   struct Type {
     // TODO(marja): To be removed. The Traits object should contain all the data
     // it needs.
     typedef PreParser* Parser;
 
     // Used by FunctionState and BlockState.
     typedef PreParserScope Scope;
     typedef PreParserScope ScopePtr;
 
-    class Checkpoint BASE_EMBEDDED {
-     public:
-      template <typename Parser>
-      explicit Checkpoint(Parser* parser) {}
-      void Restore() {}
-    };
-
     // PreParser doesn't need to store generator variables.
     typedef void GeneratorVariable;
     // No interaction with Zones.
     typedef void Zone;
 
     typedef int AstProperties;
     typedef Vector<PreParserIdentifier> ParameterIdentifierVector;
 
     // Return types for traversing functions.
     typedef PreParserIdentifier Identifier;
     typedef PreParserExpression Expression;
     typedef PreParserExpression YieldExpression;
     typedef PreParserExpression FunctionLiteral;
     typedef PreParserExpression ObjectLiteralProperty;
     typedef PreParserExpression Literal;
     typedef PreParserExpressionList ExpressionList;
     typedef PreParserExpressionList PropertyList;
     typedef PreParserStatementList StatementList;
 
     // For constructing objects returned by the traversing functions.
     typedef PreParserFactory Factory;
   };
 
+  class Checkpoint;
+
   explicit PreParserTraits(PreParser* pre_parser) : pre_parser_(pre_parser) {}
 
   // Custom operations executed when FunctionStates are created and
   // destructed. (The PreParser doesn't need to do anything.)
   template<typename FunctionState>
   static void SetUpFunctionState(FunctionState* function_state, void*) {}
   template<typename FunctionState>
   static void TearDownFunctionState(FunctionState* function_state, void*) {}
 
   // Helper functions for recursive descent.
@@ skipping 905 matching lines @@
   //   YieldExpression
   //   LeftHandSideExpression AssignmentOperator AssignmentExpression
 
   Scanner::Location lhs_location = scanner()->peek_location();
 
   if (peek() == Token::YIELD && is_generator()) {
     return this->ParseYieldExpression(ok);
   }
 
   if (fni_ != NULL) fni_->Enter();
-  ParserCheckpoint checkpoint(this);
+  typename Traits::Checkpoint checkpoint(this);
   ExpressionT expression =
       this->ParseConditionalExpression(accept_IN, CHECK_OK);
 
   if (allow_arrow_functions() && peek() == Token::ARROW) {
     checkpoint.Restore();
     expression = this->ParseArrowFunctionLiteral(lhs_location.beg_pos,
                                                  expression, CHECK_OK);
     return expression;
   }
 
@@ skipping 583 matching lines @@
 }
 
 
 #undef CHECK_OK
 #undef CHECK_OK_CUSTOM
 
 
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H