Simpler (and a bit faster) keyword matcher

src/scanner-base.h

 // 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 524 matching lines @@
 
   // Whether there is a line terminator whitespace character after
   // the current token, and  before the next. Does not count newlines
   // inside multiline comments.
   bool has_line_terminator_before_next_;
   // Whether there is a multi-line comment that contains a
   // line-terminator after the current token, and before the next.
   bool has_multiline_comment_before_next_;
 };
 
-
-// ----------------------------------------------------------------------------
-// Keyword matching state machine.
-
-class KeywordMatcher {
-//  Incrementally recognize keywords.
-//
-//  We distinguish between normal future reserved words and words that are
-//  considered to be future reserved words only in strict mode as required by
-//  ECMA-262 7.6.1.2.
-//
-//  Recognized as keywords:
-//      break, case, catch, const*, continue, debugger, default, delete, do,
-//      else, finally, false, for, function, if, in, instanceof, new, null,
-//      return, switch, this, throw, true, try, typeof, var, void, while, with.
-//
-//  Recognized as Future Reserved Keywords:
-//      class, enum, export, extends, import, super.
-//
-//  Recognized as Future Reserved Keywords (strict mode only):
-//      implements, interface, let, package, private, protected, public,
-//      static, yield.
-//
-//  *: Actually a "future reserved keyword". It's the only one we are
-//     recognizing outside of ES5 strict mode, the remaining are allowed
-//     as identifiers.
-//
- public:
-  KeywordMatcher()
-      : state_(INITIAL),
-        token_(Token::IDENTIFIER),
-        keyword_(NULL),
-        counter_(0),
-        keyword_token_(Token::ILLEGAL) {}
-
-  Token::Value token() { return token_; }
-
-  inline bool AddChar(unibrow::uchar input) {
-    if (state_ != UNMATCHABLE) {
-      Step(input);
-    }
-    return state_ != UNMATCHABLE;
-  }
-
-  void Fail() {
-    token_ = Token::IDENTIFIER;
-    state_ = UNMATCHABLE;
-  }
-
- private:
-  enum State {
-    UNMATCHABLE,
-    INITIAL,
-    KEYWORD_PREFIX,
-    KEYWORD_MATCHED,
-    C,
-    CA,
-    CO,
-    CON,
-    D,
-    DE,
-    E,
-    EX,
-    F,
-    I,
-    IM,
-    IMP,
-    IN,
-    N,
-    P,
-    PR,
-    S,
-    T,
-    TH,
-    TR,
-    V,
-    W
-  };
-
-  struct FirstState {
-    const char* keyword;
-    State state;
-    Token::Value token;
-  };
-
-  // Range of possible first characters of a keyword.
-  static const unsigned int kFirstCharRangeMin = 'b';
-  static const unsigned int kFirstCharRangeMax = 'y';
-  static const unsigned int kFirstCharRangeLength =
-      kFirstCharRangeMax - kFirstCharRangeMin + 1;
-  // State map for first keyword character range.
-  static const FirstState first_states_[kFirstCharRangeLength];
-
-  // If input equals keyword's character at position, continue matching keyword
-  // from that position.
-  inline bool MatchKeywordStart(unibrow::uchar input,
-                                const char* keyword,
-                                int position,
-                                Token::Value token_if_match) {
-    if (input != static_cast<unibrow::uchar>(keyword[position])) {
-      return false;
-    }
-    state_ = KEYWORD_PREFIX;
-    this->keyword_ = keyword;
-    this->counter_ = position + 1;
-    this->keyword_token_ = token_if_match;
-    return true;
-  }
-
-  // If input equals match character, transition to new state and return true.
-  inline bool MatchState(unibrow::uchar input, char match, State new_state) {
-    if (input != static_cast<unibrow::uchar>(match)) {
-      return false;
-    }
-    state_ = new_state;
-    return true;
-  }
-
-  inline bool MatchKeyword(unibrow::uchar input,
-                           char match,
-                           State new_state,
-                           Token::Value keyword_token) {
-    if (input != static_cast<unibrow::uchar>(match)) {
-      return false;
-    }
-    state_ = new_state;
-    token_ = keyword_token;
-    return true;
-  }
-
-  void Step(unibrow::uchar input);
-
-  // Current state.
-  State state_;
-  // Token for currently added characters.
-  Token::Value token_;
-
-  // Matching a specific keyword string (there is only one possible valid
-  // keyword with the current prefix).
-  const char* keyword_;
-  int counter_;
-  Token::Value keyword_token_;
-};
-
-
 } }  // namespace v8::internal
 
 #endif  // V8_SCANNER_BASE_H_