gomp-20050608-branch/libjava/classpath/gnu/regexp/RETokenWordBoundary.java

   1 /* gnu/regexp/RETokenWordBoundary.java
   2    Copyright (C) 2001, 2004 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package gnu.regexp;
  40
  41 /**
  42  * Represents a combination lookahead/lookbehind for POSIX [:alnum:].
  43  */
  44 final class RETokenWordBoundary extends REToken {
  45     private boolean negated;
  46     private int where;
  47     static final int BEGIN = 1;
  48     static final int END = 2;
  49
  50     RETokenWordBoundary(int subIndex, int where, boolean negated) {
  51         super(subIndex);
  52         this.where = where;
  53         this.negated = negated;
  54     }
  55
  56     boolean match(CharIndexed input, REMatch mymatch) {
  57         // Word boundary means input[index-1] was a word character
  58         // and input[index] is not, or input[index] is a word character
  59         // and input[index-1] was not
  60         //  In the string "one two three", these positions match:
  61         //  |o|n|e| |t|w|o| |t|h|r|e|e|
  62         //  ^     ^ ^     ^ ^         ^
  63         boolean after = false;  // is current character a letter or digit?
  64         boolean before = false; // is previous character a letter or digit?
  65         char ch;
  66
  67         // TODO: Also check REG_ANCHORINDEX vs. anchor
  68         if (((mymatch.eflags & RE.REG_ANCHORINDEX) != RE.REG_ANCHORINDEX)
  69             || (mymatch.offset + mymatch.index > mymatch.anchor)) {
  70             if ((ch = input.charAt(mymatch.index - 1)) != CharIndexed.OUT_OF_BOUNDS) {
  71                 before = Character.isLetterOrDigit(ch) || (ch == '_');
  72             }
  73         }
  74
  75         if ((ch = input.charAt(mymatch.index)) != CharIndexed.OUT_OF_BOUNDS) {
  76             after = Character.isLetterOrDigit(ch) || (ch == '_');
  77         }
  78
  79         // if (before) and (!after), we're at end (\>)
  80         // if (after) and (!before), we're at beginning (\<)
  81         boolean doNext = false;
  82
  83         if ((where & BEGIN) == BEGIN) {
  84             doNext = after && !before;
  85         }
  86         if ((where & END) == END) {
  87             doNext ^= before && !after;
  88         }
  89
  90         if (negated) doNext = !doNext;
  91
  92         return (doNext ? next(input, mymatch) : false);
  93     }
  94
  95     void dump(StringBuffer os) {
  96         if (where == (BEGIN | END)) {
  97             os.append( negated ? "\\B" : "\\b" );
  98         } else if (where == BEGIN) {
  99             os.append("\\<");
 100         } else {
 101             os.append("\\>");
 102         }
 103     }
 104 }