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;
059:
060: import java.util.List;
061:
062: /**
063: * Holds a "delta" difference between to revisions of a text.
064: *
065: * @version $Revision: 1.1 $ $Date: 2006/03/12 00:24:21 $
066: *
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
072: *
073: * modifications
074: *
075: * 27 Apr 2003 bwm
076: *
077: * Added getOriginal() and getRevised() accessor methods Added visitor pattern
078: * accept() method
079: */
080:
081: public abstract class Delta extends ToString {
082:
083: protected Chunk original;
084:
085: protected Chunk revised;
086:
087: static Class[][] DeltaClass;
088:
089: static {
090: DeltaClass = new Class[2][2];
091: try {
092: DeltaClass[0][0] = ChangeDelta.class;
093: DeltaClass[0][1] = AddDelta.class;
094: DeltaClass[1][0] = DeleteDelta.class;
095: DeltaClass[1][1] = ChangeDelta.class;
096: } catch (Throwable o) {
097:
098: }
099: }
100:
101: /**
102: * Returns a Delta that corresponds to the given chunks in the original and
103: * revised text respectively.
104: *
105: * @param orig
106: * the chunk in the original text.
107: * @param rev
108: * the chunk in the revised text.
109: * @return Delta
110: */
111: public static Delta newDelta(Chunk orig, Chunk rev) {
112: Class c = DeltaClass[orig.size() > 0 ? 1 : 0][rev.size() > 0 ? 1
113: : 0];
114: Delta result;
115: try {
116: result = (Delta) c.newInstance();
117: } catch (Throwable e) {
118: return null;
119: }
120: result.init(orig, rev);
121: return result;
122: }
123:
124: /**
125: * Creates an uninitialized delta.
126: */
127: protected Delta() {
128: }
129:
130: /**
131: * Creates a delta object with the given chunks from the original and
132: * revised texts.
133: * @param orig
134: * @param rev
135: */
136: protected Delta(Chunk orig, Chunk rev) {
137: init(orig, rev);
138: }
139:
140: /**
141: * Initializaes the delta with the given chunks from the original and
142: * revised texts.
143: * @param orig
144: * @param rev
145: */
146: protected void init(Chunk orig, Chunk rev) {
147: original = orig;
148: revised = rev;
149: }
150:
151: /**
152: * Verifies that this delta can be used to patch 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 abstract void verify(List target)
160: throws PatchFailedException;
161:
162: /**
163: * Applies this delta as a patch to the given text.
164: *
165: * @param target
166: * the text to patch.
167: * @throws PatchFailedException
168: * if the patch cannot be applied.
169: */
170: public final void patch(List target) throws PatchFailedException {
171: verify(target);
172: try {
173: applyTo(target);
174: } catch (Exception e) {
175: throw new PatchFailedException(e.getMessage());
176: }
177: }
178:
179: /**
180: * Applies this delta as a patch to the given text.
181: *
182: * @param target
183: * the text to patch.
184: * @throws PatchFailedException
185: * if the patch cannot be applied.
186: */
187: public abstract void applyTo(List target);
188:
189: /**
190: * Converts this delta into its Unix diff style string representation.
191: *
192: * @param s
193: * a {@link StringBuffer StringBuffer} to which the string
194: * representation will be appended.
195: */
196: public void toString(StringBuffer s) {
197: original.rangeString(s);
198: s.append("x");
199: revised.rangeString(s);
200: s.append(Diff.NL);
201: original.toString(s, "> ", "\n");
202: s.append("---");
203: s.append(Diff.NL);
204: revised.toString(s, "< ", "\n");
205: }
206:
207: /**
208: * Converts this delta into its RCS style string representation.
209: *
210: * @param s
211: * a {@link StringBuffer StringBuffer} to which the string
212: * representation will be appended.
213: * @param EOL
214: * the string to use as line separator.
215: */
216: public abstract void toRCSString(StringBuffer s, String EOL);
217:
218: /**
219: * Converts this delta into its RCS style string representation.
220: *
221: * @param EOL
222: * the string to use as line separator.
223: * @return String
224: */
225: public String toRCSString(String EOL) {
226: StringBuffer s = new StringBuffer();
227: toRCSString(s, EOL);
228: return s.toString();
229: }
230:
231: /**
232: * Accessor method to return the chunk representing the original sequence of
233: * items
234: *
235: * @return the original sequence
236: */
237: public Chunk getOriginal() {
238: return original;
239: }
240:
241: /**
242: * Accessor method to return the chunk representing the updated sequence of
243: * items.
244: *
245: * @return the updated sequence
246: */
247: public Chunk getRevised() {
248: return revised;
249: }
250:
251: /**
252: * Accepts a visitor.
253: * <p>
254: * See the Visitor pattern in "Design Patterns" by the GOF4.
255: *
256: * @param visitor
257: * The visitor.
258: */
259: public abstract void accept(RevisionVisitor visitor);
260: }
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