2003/06/28 06:54:18

[org.ibex.core.git] / src / gnu / regexp / RETokenWordBoundary.java

diff --git a/src/gnu/regexp/RETokenWordBoundary.java b/src/gnu/regexp/RETokenWordBoundary.java
new file mode 100644 (file)
index 0000000..dd8f478
--- /dev/null
+++ b/src/gnu/regexp/RETokenWordBoundary.java
@@ -0,0 +1,85 @@
+/*
+ *  gnu/regexp/RETokenWordBoundary.java
+ *  Copyright (C) 2001 Wes Biggs
+ *
+ *  This library is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published
+ *  by the Free Software Foundation; either version 2.1 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+package gnu.regexp;
+
+/**
+ * Represents a combination lookahead/lookbehind for POSIX [:alnum:].
+ */
+final class RETokenWordBoundary extends REToken {
+    private boolean negated;
+    private int where;
+    static final int BEGIN = 1;
+    static final int END = 2;
+
+    RETokenWordBoundary(int subIndex, int where, boolean negated) {
+       super(subIndex);
+       this.where = where;
+       this.negated = negated;
+    }
+    
+    boolean match(CharIndexed input, REMatch mymatch) {
+       // Word boundary means input[index-1] was a word character
+       // and input[index] is not, or input[index] is a word character
+       // and input[index-1] was not
+       //  In the string "one two three", these positions match:
+       //  |o|n|e| |t|w|o| |t|h|r|e|e|
+       //  ^     ^ ^     ^ ^         ^
+       boolean after = false;  // is current character a letter or digit?
+       boolean before = false; // is previous character a letter or digit?
+       char ch;
+
+       // TODO: Also check REG_ANCHORINDEX vs. anchor
+       if (((mymatch.eflags & RE.REG_ANCHORINDEX) != RE.REG_ANCHORINDEX) 
+           || (mymatch.offset + mymatch.index > mymatch.anchor)) {
+           if ((ch = input.charAt(mymatch.index - 1)) != CharIndexed.OUT_OF_BOUNDS) {
+               before = Character.isLetterOrDigit(ch) || (ch == '_');
+           }
+       }
+
+       if ((ch = input.charAt(mymatch.index)) != CharIndexed.OUT_OF_BOUNDS) {
+           after = Character.isLetterOrDigit(ch) || (ch == '_');
+       }
+
+       // if (before) and (!after), we're at end (\>)
+       // if (after) and (!before), we're at beginning (\<)
+       boolean doNext = false;
+
+       if ((where & BEGIN) == BEGIN) {
+           doNext = after && !before;
+       }
+       if ((where & END) == END) {
+           doNext ^= before && !after;
+       }
+
+       if (negated) doNext = !doNext;
+
+       return (doNext ? next(input, mymatch) : false);
+    }
+    
+    void dump(StringBuffer os) {
+       if (where == (BEGIN | END)) {
+           os.append( negated ? "\\B" : "\\b" );
+       } else if (where == BEGIN) {
+           os.append("\\<");
+       } else {
+           os.append("\\>");
+       }
+    }
+}