src/scanner-base.h

// Copyright 2010 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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//       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
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//       with the distribution.
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//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// Features shared by parsing and pre-parsing scanners.

#ifndef V8_SCANNER_BASE_H_
#define V8_SCANNER_BASE_H_

#include "token.h"
#include "unicode.h"

namespace v8 {
namespace internal {

class KeywordMatcher {
//  Incrementally recognize keywords.
//
//  Recognized keywords:
//      break case catch const* continue debugger* default delete do else
//      finally false for function if in instanceof native* new null
//      return switch this throw true try typeof var void while with
//
//  *: Actually "future reserved keywords". These are the only ones we
//     recognized, 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 void AddChar(unibrow::uchar input) {
    if (state_ != UNMATCHABLE) {
      Step(input);
    }
  }

  void Fail() {
    token_ = Token::IDENTIFIER;
    state_ = UNMATCHABLE;
  }

 private:
  enum State {
    UNMATCHABLE,
    INITIAL,
    KEYWORD_PREFIX,
    KEYWORD_MATCHED,
    C,
    CA,
    CO,
    CON,
    D,
    DE,
    F,
    I,
    IN,
    N,
    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 = 'w';
  static const unsigned int kFirstCharRangeLength =
      kFirstCharRangeMax - kFirstCharRangeMin + 1;
  // State map for first keyword character range.
  static 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])) {
      state_ = KEYWORD_PREFIX;
      this->keyword_ = keyword;
      this->counter_ = position + 1;
      this->keyword_token_ = token_if_match;
      return true;
    }
    return false;
  }

  // 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)) {
      state_ = new_state;
      return true;
    }
    return false;
  }

  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_