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Java > Open Source Codes > org > apache > commons > jrcs > diff > myers > PathNode


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57
58 package org.apache.commons.jrcs.diff.myers;
59
60 /**
61  * A node in a diffpath.
62  *
63  * @version $Revision: 1.1 $ $Date: 2004/10/06 09:47:23 $
64  * @author <a HREF="mailto:juanco@suigeneris.org">Juanco Anez</a>
65  *
66  * @see DiffNode
67  * @see Snake
68  *
69  */
70 public abstract class PathNode
71 {
72     /** Position in the original sequence. */
73     public final int i;
74     /** Position in the revised sequence. */
75     public final int j;
76     /** The previous node in the path. */
77     public final PathNode prev;
78
79     /**
80      * Concatenates a new path node with an existing diffpath.
81      * @param i The position in the original sequence for the new node.
82      * @param j The position in the revised sequence for the new node.
83      * @param prev The previous node in the path.
84      */
85     public PathNode(int i, int j, PathNode prev)
86     {
87         this.i = i;
88         this.j = j;
89         this.prev = prev;
90     }
91
92     /**
93      * Is this node a {@link Snake Snake node}?
94      * @return true if this is a {@link Snake Snake node}
95      */
96     public abstract boolean isSnake();
97
98     /**
99      * Is this a bootstrap node?
100      * <p>
101      * In bottstrap nodes one of the two corrdinates is
102      * less than zero.
103      * @return tru if this is a bootstrap node.
104      */
105     public boolean isBootstrap()
106     {
107         return i < 0 || j < 0;
108     }
109
110     /**
111      * Skips sequences of {@link DiffNode DiffNodes} until a
112      * {@link Snake} or bootstrap node is found, or the end
113      * of the path is reached.
114      * @return The next first {@link Snake} or bootstrap node in the path, or
115      * <code>null</code>
116      * if none found.
117      */
118     public final PathNode previousSnake()
119     {
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 JavaDoc toString()
131     {
132         StringBuffer JavaDoc buf = new StringBuffer JavaDoc("[");
133         PathNode node = this;
134         while (node != null)
135         {
136             buf.append("(");
137             buf.append(Integer.toString(node.i));
138             buf.append(",");
139             buf.append(Integer.toString(node.j));
140             buf.append(")");
141             node = node.prev;
142         }
143         buf.append("]");
144         return buf.toString();
145     }
146 }
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