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 org.apache.commons.jrcs.diff;
059:
060: import java.util.List;
061:
062: /**
063: * Holds a "delta" difference between to revisions of a text.
064: *
065: * @version $Revision: 15101 $ $Date: 2006-04-12 18:30:19 +0100 (Wed, 12 Apr
066: * 2006) $
067: * @author <a href="mailto:juanco@suigeneris.org">Juanco Anez</a>
068: * @author <a href="mailto:bwm@hplb.hpl.hp.com">Brian McBride</a>
069: * @see Diff
070: * @see Chunk
071: * @see Revision modifications 27 Apr 2003 bwm Added getOriginal() and
072: * getRevised() accessor methods Added visitor pattern accept() method
073: */
074:
075: public abstract class Delta extends
076: org.apache.commons.jrcs.util.ToString {
077:
078: protected Chunk original;
079:
080: protected Chunk revised;
081:
082: static Class[][] DeltaClass;
083:
084: static {
085: DeltaClass = new Class[2][2];
086: DeltaClass[0][0] = org.apache.commons.jrcs.diff.ChangeDelta.class;
087: DeltaClass[0][1] = org.apache.commons.jrcs.diff.AddDelta.class;
088: DeltaClass[1][0] = org.apache.commons.jrcs.diff.DeleteDelta.class;
089: DeltaClass[1][1] = org.apache.commons.jrcs.diff.ChangeDelta.class;
090: }
091:
092: /**
093: * Returns a Delta that corresponds to the given chunks in the original and
094: * revised text respectively.
095: *
096: * @param orig
097: * the chunk in the original text.
098: * @param rev
099: * the chunk in the revised text.
100: */
101: public static Delta newDelta(Chunk orig, Chunk rev) {
102: Class c = DeltaClass[orig.size() > 0 ? 1 : 0][rev.size() > 0 ? 1
103: : 0];
104: Delta result;
105: try {
106: result = (Delta) c.newInstance();
107: } catch (InstantiationException e) {
108: return null;
109: } catch (IllegalAccessException e) {
110: return null;
111: }
112: result.init(orig, rev);
113: return result;
114: }
115:
116: /**
117: * Creates an uninitialized delta.
118: */
119: protected Delta() {
120: // default constructor
121: }
122:
123: /**
124: * Creates a delta object with the given chunks from the original and
125: * revised texts.
126: */
127: protected Delta(Chunk orig, Chunk rev) {
128: init(orig, rev);
129: }
130:
131: /**
132: * Initializaes the delta with the given chunks from the original and
133: * revised texts.
134: */
135: protected void init(Chunk orig, Chunk rev) {
136: original = orig;
137: revised = rev;
138: }
139:
140: /**
141: * Verifies that this delta can be used to patch the given text.
142: *
143: * @param target
144: * the text to patch.
145: * @throws PatchFailedException
146: * if the patch cannot be applied.
147: */
148: public abstract void verify(List target)
149: throws PatchFailedException;
150:
151: /**
152: * Applies this delta as a patch to the given text.
153: *
154: * @param target
155: * the text to patch.
156: * @throws PatchFailedException
157: * if the patch cannot be applied.
158: */
159: public final void patch(List target) throws PatchFailedException {
160: verify(target);
161: try {
162: applyTo(target);
163: } catch (Exception e) {
164: throw new PatchFailedException(e.getMessage(), e);
165: }
166: }
167:
168: /**
169: * Applies this delta as a patch to the given text.
170: *
171: * @param target
172: * the text to patch.
173: * @throws PatchFailedException
174: * if the patch cannot be applied.
175: */
176: public abstract void applyTo(List target);
177:
178: /**
179: * Converts this delta into its Unix diff style string representation.
180: *
181: * @param s
182: * a {@link StringBuffer StringBuffer} to which the string
183: * representation will be appended.
184: */
185: public void toString(StringBuffer s) {
186: original.rangeString(s);
187: s.append("x");
188: revised.rangeString(s);
189: s.append(Diff.NL);
190: original.toString(s, "> ", "\n");
191: s.append("---");
192: s.append(Diff.NL);
193: revised.toString(s, "< ", "\n");
194: }
195:
196: /**
197: * Converts this delta into its RCS style string representation.
198: *
199: * @param s
200: * a {@link StringBuffer StringBuffer} to which the string
201: * representation will be appended.
202: * @param EOL
203: * the string to use as line separator.
204: */
205: public abstract void toRCSString(StringBuffer s, String EOL);
206:
207: /**
208: * Converts this delta into its RCS style string representation.
209: *
210: * @param EOL
211: * the string to use as line separator.
212: */
213: public String toRCSString(String EOL) {
214: StringBuffer s = new StringBuffer();
215: toRCSString(s, EOL);
216: return s.toString();
217: }
218:
219: /**
220: * Accessor method to return the chunk representing the original sequence of
221: * items
222: *
223: * @return the original sequence
224: */
225: public Chunk getOriginal() {
226: return original;
227: }
228:
229: /**
230: * Accessor method to return the chunk representing the updated sequence of
231: * items.
232: *
233: * @return the updated sequence
234: */
235: public Chunk getRevised() {
236: return revised;
237: }
238:
239: /**
240: * Accepts a visitor.
241: * <p>
242: * See the Visitor pattern in "Design Patterns" by the GOF4.
243: *
244: * @param visitor
245: * The visitor.
246: */
247: public abstract void accept(RevisionVisitor visitor);
248: }
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