Traitify ParserBase and move functions there.

src/preparser.h

 // Copyright 2012 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 18 matching lines @@
 #define V8_PREPARSER_H
 
 #include "hashmap.h"
 #include "token.h"
 #include "scanner.h"
 
 namespace v8 {
 namespace internal {
 
 // Common base class shared between parser and pre-parser.
+template <typename Traits>
 class ParserBase {
  public:
-  ParserBase(Scanner* scanner, uintptr_t stack_limit)
-      : scanner_(scanner),
+  ParserBase(Scanner* scanner, uintptr_t stack_limit, Traits* traits)
+      : traits_(traits),
+        scanner_(scanner),
         stack_limit_(stack_limit),
         stack_overflow_(false),
         allow_lazy_(false),
         allow_natives_syntax_(false),
         allow_generators_(false),
         allow_for_of_(false) { }
-  // TODO(mstarzinger): Only virtual until message reporting has been unified.
-  virtual ~ParserBase() { }
+  ~ParserBase() {
+    delete traits_;

[Michael Starzinger, 2014/02/10 13:28:03]

It feels dangerous to have the ownership of the Traits object be transferred to
the parser. Could we avoid that?

[marja, 2014/02/10 15:02:07]

Done. but this is not pretty either:

1) Functions in preparser.h cannot just say GetSymbol() etc. ("there are no
arguments to nnn that depend on a template parameter, so a declaration of mmm
must be available")

2) Functions in parser.cc can say GetSymbol() etc., but all functions will
eventually move to ParserBase, so, it's not much use.

3) ReportMessage exists on multiple levels of the class hierarchy with different
parameters, so, to get the right version called, I need to qualify with the
class.

+  }
 
   // Getters that indicate whether certain syntactical constructs are
   // allowed to be parsed by this instance of the parser.
   bool allow_lazy() const { return allow_lazy_; }
   bool allow_natives_syntax() const { return allow_natives_syntax_; }
   bool allow_generators() const { return allow_generators_; }
   bool allow_for_of() const { return allow_for_of_; }
   bool allow_modules() const { return scanner()->HarmonyModules(); }
   bool allow_harmony_scoping() const { return scanner()->HarmonyScoping(); }
   bool allow_harmony_numeric_literals() const {
@@ skipping 19 matching lines @@
     kAllowEvalOrArguments,
     kDontAllowEvalOrArguments
   };
 
   Scanner* scanner() const { return scanner_; }
   int position() { return scanner_->location().beg_pos; }
   int peek_position() { return scanner_->peek_location().beg_pos; }
   bool stack_overflow() const { return stack_overflow_; }
   void set_stack_overflow() { stack_overflow_ = true; }
 
-  virtual bool is_classic_mode() = 0;
-
   INLINE(Token::Value peek()) {
     if (stack_overflow_) return Token::ILLEGAL;
     return scanner()->peek();
   }
 
   INLINE(Token::Value Next()) {
     if (stack_overflow_) return Token::ILLEGAL;
     {
       int marker;
       if (reinterpret_cast<uintptr_t>(&marker) < stack_limit_) {
@@ skipping 23 matching lines @@
   }
 
   void Expect(Token::Value token, bool* ok) {
     Token::Value next = Next();
     if (next != token) {
       ReportUnexpectedToken(next);
       *ok = false;
     }
   }
 
-  bool peek_any_identifier();
-  void ExpectSemicolon(bool* ok);
-  bool CheckContextualKeyword(Vector<const char> keyword);
-  void ExpectContextualKeyword(Vector<const char> keyword, bool* ok);
+  void ExpectSemicolon(bool* ok) {
+    // Check for automatic semicolon insertion according to
+    // the rules given in ECMA-262, section 7.9, page 21.
+    Token::Value tok = peek();
+    if (tok == Token::SEMICOLON) {
+      Next();
+      return;
+    }
+    if (scanner()->HasAnyLineTerminatorBeforeNext() ||
+        tok == Token::RBRACE ||
+        tok == Token::EOS) {
+      return;
+    }
+    Expect(Token::SEMICOLON, ok);
+  }
 
-  // Strict mode octal literal validation.
-  void CheckOctalLiteral(int beg_pos, int end_pos, bool* ok);
+  bool peek_any_identifier() {
+    Token::Value next = peek();
+    return next == Token::IDENTIFIER ||
+        next == Token::FUTURE_RESERVED_WORD ||
+        next == Token::FUTURE_STRICT_RESERVED_WORD ||
+        next == Token::YIELD;
+  }
+
+  bool CheckContextualKeyword(Vector<const char> keyword) {
+    if (peek() == Token::IDENTIFIER &&
+        scanner()->is_next_contextual_keyword(keyword)) {
+      Consume(Token::IDENTIFIER);
+      return true;
+    }
+    return false;
+  }
+
+  void ExpectContextualKeyword(Vector<const char> keyword, bool* ok) {
+    Expect(Token::IDENTIFIER, ok);
+    if (!*ok) return;
+    if (!scanner()->is_literal_contextual_keyword(keyword)) {
+      ReportUnexpectedToken(scanner()->current_token());
+      *ok = false;
+    }
+  }
+
+  // Checks whether an octal literal was last seen between beg_pos and end_pos.
+  // If so, reports an error. Only called for strict mode.
+  void CheckOctalLiteral(int beg_pos, int end_pos, bool* ok) {
+    Scanner::Location octal = scanner()->octal_position();
+    if (octal.IsValid() && beg_pos <= octal.beg_pos &&
+        octal.end_pos <= end_pos) {
+      ReportMessageAt(octal, "strict_octal_literal");
+      scanner()->clear_octal_position();
+      *ok = false;
+    }
+  }
 
   // Determine precedence of given token.
-  static int Precedence(Token::Value token, bool accept_IN);
+  static int Precedence(Token::Value token, bool accept_IN) {
+    if (token == Token::IN && !accept_IN)
+      return 0;  // 0 precedence will terminate binary expression parsing
+    return Token::Precedence(token);
+  }
 
   // Report syntax errors.
+  void ReportMessage(const char* message, Vector<const char*> args) {
+    Scanner::Location source_location = scanner()->location();
+    ReportMessageAt(source_location, message, args);
+  }
+
+  void ReportMessageAt(Scanner::Location location, const char* message) {
+    ReportMessageAt(location, message, Vector<const char*>::empty());
+  }
+
+  void ReportMessageAt(Scanner::Location source_location,
+                       const char* message,
+                       Vector<const char*> args) {
+    traits_->ReportMessageAt(source_location, message, args);
+  }
+
   void ReportUnexpectedToken(Token::Value token);
-  void ReportMessageAt(Scanner::Location location, const char* type) {
-    ReportMessageAt(location, type, Vector<const char*>::empty());
-  }
-  virtual void ReportMessageAt(Scanner::Location source_location,
-                               const char* message,
-                               Vector<const char*> args) = 0;
+
+  // Recursive descent functions:
+
+  // Parses an identifier that is valid for the current scope, in particular it
+  // fails on strict mode future reserved keywords in a strict scope. If
+  // allow_eval_or_arguments is kAllowEvalOrArguments, we allow "eval" or
+  // "arguments" as identifier even in strict mode (this is needed in cases like
+  // "var foo = eval;").
+  typename Traits::IdentifierType ParseIdentifier(
+      AllowEvalOrArgumentsAsIdentifier,
+      bool* ok);
+  // Parses an identifier or a strict mode future reserved word, and indicate
+  // whether it is strict mode future reserved.
+  typename Traits::IdentifierType ParseIdentifierOrStrictReservedWord(
+      bool* is_strict_reserved,
+      bool* ok);
+  typename Traits::IdentifierType ParseIdentifierName(bool* ok);
+  // Parses an identifier and determines whether or not it is 'get' or 'set'.
+  typename Traits::IdentifierType ParseIdentifierNameOrGetOrSet(bool* is_get,
+                                                                bool* is_set,
+                                                                bool* ok);
 
   // Used to detect duplicates in object literals. Each of the values
   // kGetterProperty, kSetterProperty and kValueProperty represents
   // a type of object literal property. When parsing a property, its
   // type value is stored in the DuplicateFinder for the property name.
   // Values are chosen so that having intersection bits means the there is
   // an incompatibility.
   // I.e., you can add a getter to a property that already has a setter, since
   // kGetterProperty and kSetterProperty doesn't intersect, but not if it
   // already has a getter or a value. Adding the getter to an existing
@@ skipping 35 matching lines @@
     }
     bool IsAccessorAccessorConflict(PropertyKind type1, PropertyKind type2) {
       return ((type1 | type2) & kValueFlag) == 0;
     }
 
     ParserBase* parser_;
     DuplicateFinder finder_;
     LanguageMode language_mode_;
   };
 
+  Traits* traits_;
+
  private:
   Scanner* scanner_;
   uintptr_t stack_limit_;
   bool stack_overflow_;
 
   bool allow_lazy_;
   bool allow_natives_syntax_;
   bool allow_generators_;
   bool allow_for_of_;
 };
 
 
 // Preparsing checks a JavaScript program and emits preparse-data that helps
 // a later parsing to be faster.
 // See preparse-data-format.h for the data format.
 
 // The PreParser checks that the syntax follows the grammar for JavaScript,
 // and collects some information about the program along the way.
 // The grammar check is only performed in order to understand the program
 // sufficiently to deduce some information about it, that can be used
 // to speed up later parsing. Finding errors is not the goal of pre-parsing,
 // rather it is to speed up properly written and correct programs.
 // That means that contextual checks (like a label being declared where
 // it is used) are generally omitted.
-class PreParser : public ParserBase {
+
+class PreParserIdentifier {
  public:
+  static PreParserIdentifier Default() {
+    return PreParserIdentifier(kUnknownIdentifier);
+  }
+  static PreParserIdentifier Eval() {
+    return PreParserIdentifier(kEvalIdentifier);
+  }
+  static PreParserIdentifier Arguments() {
+    return PreParserIdentifier(kArgumentsIdentifier);
+  }
+  static PreParserIdentifier FutureReserved() {
+    return PreParserIdentifier(kFutureReservedIdentifier);
+  }
+  static PreParserIdentifier FutureStrictReserved() {
+    return PreParserIdentifier(kFutureStrictReservedIdentifier);
+  }
+  static PreParserIdentifier Yield() {
+    return PreParserIdentifier(kYieldIdentifier);
+  }
+  bool IsEval() { return type_ == kEvalIdentifier; }
+  bool IsArguments() { return type_ == kArgumentsIdentifier; }
+  bool IsEvalOrArguments() { return type_ >= kEvalIdentifier; }
+  bool IsYield() { return type_ == kYieldIdentifier; }
+  bool IsFutureReserved() { return type_ == kFutureReservedIdentifier; }
+  bool IsFutureStrictReserved() {
+    return type_ == kFutureStrictReservedIdentifier;
+  }
+  bool IsValidStrictVariable() { return type_ == kUnknownIdentifier; }
+
+ private:
+  enum Type {
+    kUnknownIdentifier,
+    kFutureReservedIdentifier,
+    kFutureStrictReservedIdentifier,
+    kYieldIdentifier,
+    kEvalIdentifier,
+    kArgumentsIdentifier
+  };
+  explicit PreParserIdentifier(Type type) : type_(type) {}
+  Type type_;
+
+  friend class PreParserExpression;
+};
+
+
+// Bits 0 and 1 are used to identify the type of expression:
+// If bit 0 is set, it's an identifier.
+// if bit 1 is set, it's a string literal.
+// If neither is set, it's no particular type, and both set isn't
+// use yet.
+class PreParserExpression {
+ public:
+  static PreParserExpression Default() {
+    return PreParserExpression(kUnknownExpression);
+  }
+
+  static PreParserExpression FromIdentifier(PreParserIdentifier id) {
+    return PreParserExpression(kIdentifierFlag |
+                               (id.type_ << kIdentifierShift));
+  }
+
+  static PreParserExpression StringLiteral() {
+    return PreParserExpression(kUnknownStringLiteral);
+  }
+
+  static PreParserExpression UseStrictStringLiteral() {
+    return PreParserExpression(kUseStrictString);
+  }
+
+  static PreParserExpression This() {
+    return PreParserExpression(kThisExpression);
+  }
+
+  static PreParserExpression ThisProperty() {
+    return PreParserExpression(kThisPropertyExpression);
+  }
+
+  static PreParserExpression StrictFunction() {
+    return PreParserExpression(kStrictFunctionExpression);
+  }
+
+  bool IsIdentifier() { return (code_ & kIdentifierFlag) != 0; }
+
+  // Only works corretly if it is actually an identifier expression.
+  PreParserIdentifier AsIdentifier() {
+    return PreParserIdentifier(
+        static_cast<PreParserIdentifier::Type>(code_ >> kIdentifierShift));
+  }
+
+  bool IsStringLiteral() { return (code_ & kStringLiteralFlag) != 0; }
+
+  bool IsUseStrictLiteral() {
+    return (code_ & kStringLiteralMask) == kUseStrictString;
+  }
+
+  bool IsThis() { return code_ == kThisExpression; }
+
+  bool IsThisProperty() { return code_ == kThisPropertyExpression; }
+
+  bool IsStrictFunction() { return code_ == kStrictFunctionExpression; }
+
+ private:
+  // First two/three bits are used as flags.
+  // Bit 0 and 1 represent identifiers or strings literals, and are
+  // mutually exclusive, but can both be absent.
+  enum {
+    kUnknownExpression = 0,
+    // Identifiers
+    kIdentifierFlag = 1,  // Used to detect labels.
+    kIdentifierShift = 3,
+
+    kStringLiteralFlag = 2,  // Used to detect directive prologue.
+    kUnknownStringLiteral = kStringLiteralFlag,
+    kUseStrictString = kStringLiteralFlag | 8,
+    kStringLiteralMask = kUseStrictString,
+
+    // Below here applies if neither identifier nor string literal.
+    kThisExpression = 4,
+    kThisPropertyExpression = 8,
+    kStrictFunctionExpression = 12
+  };
+
+  explicit PreParserExpression(int expression_code) : code_(expression_code) {}
+
+  int code_;
+};
+
+class PreParser;
+
+
+class PreParserTraits {
+ public:
+  // Return types for traversing functions.
+  typedef PreParserIdentifier IdentifierType;
+
+  explicit PreParserTraits(PreParser* pre_parser) : pre_parser_(pre_parser) {}
+
+  // Helper functions for recursive descent.
+  bool is_classic_mode() const;
+  bool is_generator() const;
+  static bool IsEvalOrArguments(IdentifierType identifier) {
+    return identifier.IsEvalOrArguments();
+  }
+
+  // Reporting errors.
+  void ReportMessageAt(Scanner::Location location,
+                       const char* message,
+                       Vector<const char*> args);
+  void ReportMessageAt(Scanner::Location location,
+                       const char* type,
+                       const char* name_opt);
+  void ReportMessageAt(int start_pos,
+                       int end_pos,
+                       const char* type,
+                       const char* name_opt);
+
+  // Identifiers:
+  static IdentifierType EmptyIdentifier() {
+    return PreParserIdentifier::Default();
+  }
+
+  IdentifierType GetSymbol();
+
+ private:
+  PreParser* pre_parser_;
+};
+
+
+class PreParser : public ParserBase<PreParserTraits> {
+ public:
+  typedef PreParserIdentifier Identifier;
+  typedef PreParserExpression Expression;
+
   enum PreParseResult {
     kPreParseStackOverflow,
     kPreParseSuccess
   };
 
   PreParser(Scanner* scanner,
             ParserRecorder* log,
             uintptr_t stack_limit)
-      : ParserBase(scanner, stack_limit),
+      : ParserBase(scanner, stack_limit, new PreParserTraits(this)),
         log_(log),
         scope_(NULL),
         parenthesized_function_(false) { }
 
   ~PreParser() {}
 
   // Pre-parse the program from the character stream; returns true on
   // success (even if parsing failed, the pre-parse data successfully
   // captured the syntax error), and false if a stack-overflow happened
   // during parsing.
@@ skipping 17 matching lines @@
   // detail that it can be lazily compiled.
   // The scanner is expected to have matched the "function" or "function*"
   // keyword and parameters, and have consumed the initial '{'.
   // At return, unless an error occurred, the scanner is positioned before the
   // the final '}'.
   PreParseResult PreParseLazyFunction(LanguageMode mode,
                                       bool is_generator,
                                       ParserRecorder* log);
 
  private:
+  friend class PreParserTraits;
+
   // These types form an algebra over syntactic categories that is just
   // rich enough to let us recognize and propagate the constructs that
   // are either being counted in the preparser data, or is important
   // to throw the correct syntax error exceptions.
 
   enum ScopeType {
     kTopLevelScope,
     kFunctionScope
   };
 
   enum VariableDeclarationContext {
     kSourceElement,
     kStatement,
     kForStatement
   };
 
   // If a list of variable declarations includes any initializers.
   enum VariableDeclarationProperties {
     kHasInitializers,
     kHasNoInitializers
   };
 
-  class Expression;
-
-  class Identifier {
-   public:
-    static Identifier Default() {
-      return Identifier(kUnknownIdentifier);
-    }
-    static Identifier Eval()  {
-      return Identifier(kEvalIdentifier);
-    }
-    static Identifier Arguments()  {
-      return Identifier(kArgumentsIdentifier);
-    }
-    static Identifier FutureReserved()  {
-      return Identifier(kFutureReservedIdentifier);
-    }
-    static Identifier FutureStrictReserved()  {
-      return Identifier(kFutureStrictReservedIdentifier);
-    }
-    static Identifier Yield()  {
-      return Identifier(kYieldIdentifier);
-    }
-    bool IsEval() { return type_ == kEvalIdentifier; }
-    bool IsArguments() { return type_ == kArgumentsIdentifier; }
-    bool IsEvalOrArguments() { return type_ >= kEvalIdentifier; }
-    bool IsYield() { return type_ == kYieldIdentifier; }
-    bool IsFutureReserved() { return type_ == kFutureReservedIdentifier; }
-    bool IsFutureStrictReserved() {
-      return type_ == kFutureStrictReservedIdentifier;
-    }
-    bool IsValidStrictVariable() { return type_ == kUnknownIdentifier; }
-
-   private:
-    enum Type {
-      kUnknownIdentifier,
-      kFutureReservedIdentifier,
-      kFutureStrictReservedIdentifier,
-      kYieldIdentifier,
-      kEvalIdentifier,
-      kArgumentsIdentifier
-    };
-    explicit Identifier(Type type) : type_(type) { }
-    Type type_;
-
-    friend class Expression;
-  };
-
-  // Bits 0 and 1 are used to identify the type of expression:
-  // If bit 0 is set, it's an identifier.
-  // if bit 1 is set, it's a string literal.
-  // If neither is set, it's no particular type, and both set isn't
-  // use yet.
-  class Expression {
-   public:
-    static Expression Default() {
-      return Expression(kUnknownExpression);
-    }
-
-    static Expression FromIdentifier(Identifier id) {
-      return Expression(kIdentifierFlag | (id.type_ << kIdentifierShift));
-    }
-
-    static Expression StringLiteral() {
-      return Expression(kUnknownStringLiteral);
-    }
-
-    static Expression UseStrictStringLiteral() {
-      return Expression(kUseStrictString);
-    }
-
-    static Expression This() {
-      return Expression(kThisExpression);
-    }
-
-    static Expression ThisProperty() {
-      return Expression(kThisPropertyExpression);
-    }
-
-    static Expression StrictFunction() {
-      return Expression(kStrictFunctionExpression);
-    }
-
-    bool IsIdentifier() {
-      return (code_ & kIdentifierFlag) != 0;
-    }
-
-    // Only works corretly if it is actually an identifier expression.
-    PreParser::Identifier AsIdentifier() {
-      return PreParser::Identifier(
-          static_cast<PreParser::Identifier::Type>(code_ >> kIdentifierShift));
-    }
-
-    bool IsStringLiteral() { return (code_ & kStringLiteralFlag) != 0; }
-
-    bool IsUseStrictLiteral() {
-      return (code_ & kStringLiteralMask) == kUseStrictString;
-    }
-
-    bool IsThis() {
-      return code_ == kThisExpression;
-    }
-
-    bool IsThisProperty() {
-      return code_ == kThisPropertyExpression;
-    }
-
-    bool IsStrictFunction() {
-      return code_ == kStrictFunctionExpression;
-    }
-
-   private:
-    // First two/three bits are used as flags.
-    // Bit 0 and 1 represent identifiers or strings literals, and are
-    // mutually exclusive, but can both be absent.
-    enum  {
-      kUnknownExpression = 0,
-      // Identifiers
-      kIdentifierFlag = 1,  // Used to detect labels.
-      kIdentifierShift = 3,
-
-      kStringLiteralFlag = 2,  // Used to detect directive prologue.
-      kUnknownStringLiteral = kStringLiteralFlag,
-      kUseStrictString = kStringLiteralFlag | 8,
-      kStringLiteralMask = kUseStrictString,
-
-      // Below here applies if neither identifier nor string literal.
-      kThisExpression = 4,
-      kThisPropertyExpression = 8,
-      kStrictFunctionExpression = 12
-    };
-
-    explicit Expression(int expression_code) : code_(expression_code) { }
-
-    int code_;
-  };
-
   class Statement {
    public:
     static Statement Default() {
       return Statement(kUnknownStatement);
     }
 
     static Statement FunctionDeclaration() {
       return Statement(kFunctionDeclaration);
     }
 
@@ skipping 90 matching lines @@
     Scope** const variable_;
     Scope* const prev_;
     const ScopeType type_;
     int materialized_literal_count_;
     int expected_properties_;
     int with_nesting_count_;
     LanguageMode language_mode_;
     bool is_generator_;
   };
 
-  // Report syntax error
-  void ReportMessageAt(Scanner::Location location,
-                       const char* message,
-                       Vector<const char*> args) {
-    ReportMessageAt(location.beg_pos,
-                    location.end_pos,
-                    message,
-                    args.length() > 0 ? args[0] : NULL);
-  }
-  void ReportMessageAt(Scanner::Location location,
-                       const char* type,
-                       const char* name_opt) {
-    log_->LogMessage(location.beg_pos, location.end_pos, type, name_opt);
-  }
-  void ReportMessageAt(int start_pos,
-                       int end_pos,
-                       const char* type,
-                       const char* name_opt) {
-    log_->LogMessage(start_pos, end_pos, type, name_opt);
-  }
-
   // All ParseXXX functions take as the last argument an *ok parameter
   // which is set to false if parsing failed; it is unchanged otherwise.
   // By making the 'exception handling' explicit, we are forced to check
   // for failure at the call sites.
   Statement ParseSourceElement(bool* ok);
   SourceElements ParseSourceElements(int end_token, bool* ok);
   Statement ParseStatement(bool* ok);
   Statement ParseFunctionDeclaration(bool* ok);
   Statement ParseBlock(bool* ok);
   Statement ParseVariableStatement(VariableDeclarationContext var_context,
@@ skipping 35 matching lines @@
 
   Arguments ParseArguments(bool* ok);
   Expression ParseFunctionLiteral(
       Identifier name,
       Scanner::Location function_name_location,
       bool name_is_strict_reserved,
       bool is_generator,
       bool* ok);
   void ParseLazyFunctionLiteralBody(bool* ok);
 
-  Identifier ParseIdentifier(AllowEvalOrArgumentsAsIdentifier, bool* ok);
-  Identifier ParseIdentifierOrStrictReservedWord(bool* is_strict_reserved,
-                                                 bool* ok);
-  Identifier ParseIdentifierName(bool* ok);
-  Identifier ParseIdentifierNameOrGetOrSet(bool* is_get,
-                                           bool* is_set,
-                                           bool* ok);
-
   // Logs the currently parsed literal as a symbol in the preparser data.
   void LogSymbol();
-  // Log the currently parsed identifier.
-  Identifier GetIdentifierSymbol();
   // Log the currently parsed string literal.
   Expression GetStringSymbol();
 
   void set_language_mode(LanguageMode language_mode) {
     scope_->set_language_mode(language_mode);
   }
 
-  virtual bool is_classic_mode() {
-    return scope_->language_mode() == CLASSIC_MODE;
-  }
-
   bool is_extended_mode() {
     return scope_->language_mode() == EXTENDED_MODE;
   }
 
   LanguageMode language_mode() { return scope_->language_mode(); }
 
   bool CheckInOrOf(bool accept_OF);
 
   ParserRecorder* log_;
   Scope* scope_;
   bool parenthesized_function_;
 };
 
+
+
+template<class Traits>
+void ParserBase<Traits>::ReportUnexpectedToken(Token::Value token) {
+  // We don't report stack overflows here, to avoid increasing the
+  // stack depth even further.  Instead we report it after parsing is
+  // over, in ParseProgram.
+  if (token == Token::ILLEGAL && stack_overflow()) {
+    return;
+  }
+  Scanner::Location source_location = scanner()->location();
+
+  // Four of the tokens are treated specially
+  switch (token) {
+    case Token::EOS:
+      return ReportMessageAt(source_location, "unexpected_eos");
+    case Token::NUMBER:
+      return ReportMessageAt(source_location, "unexpected_token_number");
+    case Token::STRING:
+      return ReportMessageAt(source_location, "unexpected_token_string");
+    case Token::IDENTIFIER:
+      return ReportMessageAt(source_location, "unexpected_token_identifier");
+    case Token::FUTURE_RESERVED_WORD:
+      return ReportMessageAt(source_location, "unexpected_reserved");
+    case Token::YIELD:
+    case Token::FUTURE_STRICT_RESERVED_WORD:
+      return ReportMessageAt(
+          source_location,
+          traits_->is_classic_mode() ? "unexpected_token_identifier"
+                                     : "unexpected_strict_reserved");
+    default:
+      const char* name = Token::String(token);
+      ASSERT(name != NULL);
+      ReportMessageAt(
+          source_location, "unexpected_token", Vector<const char*>(&name, 1));
+  }
+}
+
+
+template<class Traits>
+typename Traits::IdentifierType ParserBase<Traits>::ParseIdentifier(
+    AllowEvalOrArgumentsAsIdentifier allow_eval_or_arguments,
+    bool* ok) {
+  Token::Value next = Next();
+  if (next == Token::IDENTIFIER) {
+    typename Traits::IdentifierType name = traits_->GetSymbol();
+    if (allow_eval_or_arguments == kDontAllowEvalOrArguments &&
+        !traits_->is_classic_mode() && traits_->IsEvalOrArguments(name)) {
+      ReportMessageAt(scanner()->location(), "strict_eval_arguments");
+      *ok = false;
+    }
+    return name;
+  } else if (traits_->is_classic_mode() &&
+             (next == Token::FUTURE_STRICT_RESERVED_WORD ||
+              (next == Token::YIELD && !traits_->is_generator()))) {
+    return traits_->GetSymbol();
+  } else {
+    ReportUnexpectedToken(next);
+    *ok = false;
+    return Traits::EmptyIdentifier();
+  }
+}
+
+
+template <class Traits>
+typename Traits::IdentifierType ParserBase<
+    Traits>::ParseIdentifierOrStrictReservedWord(bool* is_strict_reserved,
+                                                 bool* ok) {
+  Token::Value next = Next();
+  if (next == Token::IDENTIFIER) {
+    *is_strict_reserved = false;
+  } else if (next == Token::FUTURE_STRICT_RESERVED_WORD ||
+             (next == Token::YIELD && !traits_->is_generator())) {
+    *is_strict_reserved = true;
+  } else {
+    ReportUnexpectedToken(next);
+    *ok = false;
+    return Traits::EmptyIdentifier();
+  }
+  return traits_->GetSymbol();
+}
+
+
+template <class Traits>
+typename Traits::IdentifierType ParserBase<Traits>::ParseIdentifierName(
+    bool* ok) {
+  Token::Value next = Next();
+  if (next != Token::IDENTIFIER && next != Token::FUTURE_RESERVED_WORD &&
+      next != Token::FUTURE_STRICT_RESERVED_WORD && !Token::IsKeyword(next)) {
+    ReportUnexpectedToken(next);
+    *ok = false;
+    return Traits::EmptyIdentifier();
+  }
+  return traits_->GetSymbol();
+}
+
+
+template <class Traits>
+typename Traits::IdentifierType
+ParserBase<Traits>::ParseIdentifierNameOrGetOrSet(bool* is_get,
+                                                  bool* is_set,
+                                                  bool* ok) {
+  typename Traits::IdentifierType result = ParseIdentifierName(ok);
+  if (!*ok) return Traits::EmptyIdentifier();
+  if (scanner()->is_literal_ascii() &&
+      scanner()->literal_length() == 3) {
+    const char* token = scanner()->literal_ascii_string().start();
+    *is_get = strncmp(token, "get", 3) == 0;
+    *is_set = !*is_get && strncmp(token, "set", 3) == 0;
+  }
+  return result;
+}
+
+
+template <typename Traits>
+void ParserBase<Traits>::ObjectLiteralChecker::CheckProperty(
+    Token::Value property,
+    PropertyKind type,
+    bool* ok) {
+  int old;
+  if (property == Token::NUMBER) {
+    old = finder_.AddNumber(scanner()->literal_ascii_string(), type);
+  } else if (scanner()->is_literal_ascii()) {
+    old = finder_.AddAsciiSymbol(scanner()->literal_ascii_string(), type);
+  } else {
+    old = finder_.AddUtf16Symbol(scanner()->literal_utf16_string(), type);
+  }
+  PropertyKind old_type = static_cast<PropertyKind>(old);
+  if (HasConflict(old_type, type)) {
+    if (IsDataDataConflict(old_type, type)) {
+      // Both are data properties.
+      if (language_mode_ == CLASSIC_MODE) return;
+      parser()->ReportMessageAt(scanner()->location(),
+                               "strict_duplicate_property");
+    } else if (IsDataAccessorConflict(old_type, type)) {
+      // Both a data and an accessor property with the same name.
+      parser()->ReportMessageAt(scanner()->location(),
+                               "accessor_data_property");
+    } else {
+      ASSERT(IsAccessorAccessorConflict(old_type, type));
+      // Both accessors of the same type.
+      parser()->ReportMessageAt(scanner()->location(),
+                               "accessor_get_set");
+    }
+    *ok = false;
+  }
+}
+
+
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H