001: /*
002: * ====================================================================
003: *
004: * The Apache Software License, Version 1.1
005: *
006: * Copyright (c) 1999-2003 The Apache Software Foundation.
007: * All rights reserved.
008: *
009: * Redistribution and use in source and binary forms, with or without
010: * modification, are permitted provided that the following conditions
011: * are met:
012: *
013: * 1. Redistributions of source code must retain the above copyright
014: * notice, this list of conditions and the following disclaimer.
015: *
016: * 2. Redistributions in binary form must reproduce the above copyright
017: * notice, this list of conditions and the following disclaimer in
018: * the documentation and/or other materials provided with the
019: * distribution.
020: *
021: * 3. The end-user documentation included with the redistribution, if
022: * any, must include the following acknowledgement:
023: * "This product includes software developed by the
024: * Apache Software Foundation (http://www.apache.org/)."
025: * Alternately, this acknowledgement may appear in the software itself,
026: * if and wherever such third-party acknowledgements normally appear.
027: *
028: * 4. The names "The Jakarta Project", "Commons", and "Apache Software
029: * Foundation" must not be used to endorse or promote products derived
030: * from this software without prior written permission. For written
031: * permission, please contact apache@apache.org.
032: *
033: * 5. Products derived from this software may not be called "Apache"
034: * nor may "Apache" appear in their names without prior written
035: * permission of the Apache Software Foundation.
036: *
037: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
038: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
039: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
040: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
041: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
042: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
043: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
044: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
045: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
046: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
047: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
048: * SUCH DAMAGE.
049: * ====================================================================
050: *
051: * This software consists of voluntary contributions made by many
052: * individuals on behalf of the Apache Software Foundation. For more
053: * information on the Apache Software Foundation, please see
054: * <http://www.apache.org/>.
055: *
056: */
057:
058: package wicket.util.diff.myers;
059:
060: /**
061: * A node in a diffpath.
062: *
063: * @version $Revision: 1.1 $ $Date: 2006/03/12 00:24:21 $
064: * @author <a href="mailto:juanco@suigeneris.org">Juanco Anez</a>
065: *
066: * @see DiffNode
067: * @see Snake
068: *
069: */
070: public abstract class PathNode {
071: /** Position in the original sequence. */
072: public final int i;
073: /** Position in the revised sequence. */
074: public final int j;
075: /** The previous node in the path. */
076: public final PathNode prev;
077:
078: /**
079: * Concatenates a new path node with an existing diffpath.
080: *
081: * @param i
082: * The position in the original sequence for the new node.
083: * @param j
084: * The position in the revised sequence for the new node.
085: * @param prev
086: * The previous node in the path.
087: */
088: public PathNode(int i, int j, PathNode prev) {
089: this .i = i;
090: this .j = j;
091: this .prev = prev;
092: }
093:
094: /**
095: * Is this node a {@link Snake Snake node}?
096: *
097: * @return true if this is a {@link Snake Snake node}
098: */
099: public abstract boolean isSnake();
100:
101: /**
102: * Is this a bootstrap node?
103: * <p>
104: * In bottstrap nodes one of the two corrdinates is less than zero.
105: *
106: * @return tru if this is a bootstrap node.
107: */
108: public boolean isBootstrap() {
109: return i < 0 || j < 0;
110: }
111:
112: /**
113: * Skips sequences of {@link DiffNode DiffNodes} until a {@link Snake} or
114: * bootstrap node is found, or the end of the path is reached.
115: *
116: * @return The next first {@link Snake} or bootstrap node in the path, or
117: * <code>null</code> if none found.
118: */
119: public final PathNode previousSnake() {
120: if (isBootstrap())
121: return null;
122: if (!isSnake() && prev != null)
123: return prev.previousSnake();
124: return this ;
125: }
126:
127: /**
128: * {@inheritDoc}
129: */
130: public String toString() {
131: StringBuffer buf = new StringBuffer("[");
132: PathNode node = this ;
133: while (node != null) {
134: buf.append("(");
135: buf.append(Integer.toString(node.i));
136: buf.append(",");
137: buf.append(Integer.toString(node.j));
138: buf.append(")");
139: node = node.prev;
140: }
141: buf.append("]");
142: return buf.toString();
143: }
144: }
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