/interpreter/tags/at2-build270707/src/edu/vub/util/regexp/RETokenLookBehind.java

  1/* gnu/regexp/RETokenLookBehind.java
  2   Copyright (C) 2006 Free Software Foundation, Inc.
  3
  4This file is part of GNU Classpath.
  5
  6GNU Classpath is free software; you can redistribute it and/or modify
  7it under the terms of the GNU General Public License as published by
  8the Free Software Foundation; either version 2, or (at your option)
  9any later version.
 10
 11GNU Classpath is distributed in the hope that it will be useful, but
 12WITHOUT ANY WARRANTY; without even the implied warranty of
 13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 14General Public License for more details.
 15
 16You should have received a copy of the GNU General Public License
 17along with GNU Classpath; see the file COPYING.  If not, write to the
 18Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 1902110-1301 USA.
 20
 21Linking this library statically or dynamically with other modules is
 22making a combined work based on this library.  Thus, the terms and
 23conditions of the GNU General Public License cover the whole
 24combination.
 25
 26As a special exception, the copyright holders of this library give you
 27permission to link this library with independent modules to produce an
 28executable, regardless of the license terms of these independent
 29modules, and to copy and distribute the resulting executable under
 30terms of your choice, provided that you also meet, for each linked
 31independent module, the terms and conditions of the license of that
 32module.  An independent module is a module which is not derived from
 33or based on this library.  If you modify this library, you may extend
 34this exception to your version of the library, but you are not
 35obligated to do so.  If you do not wish to do so, delete this
 36exception statement from your version. */
 37
 38package edu.vub.util.regexp;
 39
 40/**
 41 * @author Ito Kazumitsu
 42 */
 43final class RETokenLookBehind extends REToken
 44{
 45  REToken re;
 46  boolean negative;
 47
 48  RETokenLookBehind(REToken re, boolean negative) throws REException {
 49    super(0);
 50    this.re = re;
 51    this.negative = negative;
 52  }
 53
 54  int getMaximumLength() {
 55    return 0;
 56  }
 57
 58  boolean match(CharIndexed input, REMatch mymatch)
 59  {
 60    int max = re.getMaximumLength();
 61    CharIndexed behind = input.lookBehind(mymatch.index, max);
 62    REMatch trymatch = (REMatch)mymatch.clone();
 63    REMatch trymatch1 = (REMatch)mymatch.clone();
 64    REMatch newMatch = null;
 65    int curIndex = trymatch.index + behind.length() - input.length();
 66    trymatch.index = 0;
 67    RETokenMatchHereOnly stopper = new RETokenMatchHereOnly(curIndex);
 68    REToken re1 = (REToken) re.clone();
 69    re1.chain(stopper);
 70    if (re1.match(behind, trymatch)) {
 71      if (negative) return false;
 72      if (next(input, trymatch1))
 73        newMatch = trymatch1;
 74    }
 75
 76    if (newMatch != null) {
 77      if (negative) return false;
 78      //else
 79      mymatch.assignFrom(newMatch);
 80      return true;
 81    }
 82    else { // no match
 83      if (negative)
 84        return next(input, mymatch);
 85      //else
 86      return false;
 87    }
 88  }
 89
 90    void dump(StringBuffer os) {
 91	os.append("(?<");
 92	os.append(negative ? '!' : '=');
 93	re.dumpAll(os);
 94	os.append(')');
 95    }
 96
 97    private static class RETokenMatchHereOnly extends REToken {
 98
 99        int getMaximumLength() { return 0; }
100
101	private int index;
102
103	RETokenMatchHereOnly(int index) {
104	    super(0);
105	    this.index = index;
106	}
107
108	boolean match(CharIndexed input, REMatch mymatch) {
109	    return index == mymatch.index;
110	}
111
112        void dump(StringBuffer os) {}
113
114    }
115}
116