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comparison src/org/tmatesoft/hg/internal/PatchGenerator.java @ 533:e6f72c9829a6

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Generate patches using diff algorithm
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Wed, 30 Jan 2013 15:48:36 +0100
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children dd4f6311af52
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532:688c1ab113bb 533:e6f72c9829a6
1 /*
2 * Copyright (c) 2013 TMate Software Ltd
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 2 of the License.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * For information on how to redistribute this software under
14 * the terms of a license other than GNU General Public License
15 * contact TMate Software at support@hg4j.com
16 */
17 package org.tmatesoft.hg.internal;
18
19 import java.util.ArrayList;
20 import java.util.HashMap;
21 import java.util.Map;
22
23 import org.tmatesoft.hg.repo.HgDataFile;
24 import org.tmatesoft.hg.repo.HgLookup;
25 import org.tmatesoft.hg.repo.HgRepository;
26
27 /**
28 * Mercurial cares about changes only up to the line level, e.g. a simple file version bump in manifest looks like (RevlogDump output):
29 *
30 * 522: 233748 0 103 17438 433 522 521 -1 756073cf2321df44d3ed0585f2a5754bc8a1b2f6
31 * <PATCH>:
32 * 3487..3578, 91:src/org/tmatesoft/hg/core/HgIterateDirection.java\00add61a8a665c5d8f092210767f812fe0d335ac8
33 *
34 * I.e. for the {fname}{revision} entry format of manifest, not only {revision} is changed, but the whole line, with unchanged {fname} is recorded
35 * in the patch.
36 *
37 * Mercurial paper describes reasons for choosing this approach to delta generation, too.
38 *
39 *
40 * @author Artem Tikhomirov
41 * @author TMate Software Ltd.
42 */
43 public class PatchGenerator {
44
45 private Map<ChunkSequence.ByteChain, IntVector> chunk2UseIndex;
46 private ChunkSequence seq1, seq2;
47
48 // get filled by #longestMatch, track start of common sequence in seq1 and seq2, respectively
49 private int matchStartS1, matchStartS2;
50 // get filled by #findMatchingBlocks, track start of changed/unknown sequence in seq1 and seq2
51 private int changeStartS1, changeStartS2;
52
53 public void init(byte[] data1, byte[] data2) {
54 seq1 = new ChunkSequence(data1);
55 seq1.splitByNewlines();
56 seq2 = new ChunkSequence(data2);
57 seq2.splitByNewlines();
58 prepare(seq2);
59 }
60
61 private void prepare(ChunkSequence s2) {
62 chunk2UseIndex = new HashMap<ChunkSequence.ByteChain, IntVector>();
63 for (int i = 0, len = s2.chunkCount(); i < len; i++) {
64 ChunkSequence.ByteChain bc = s2.chunk(i);
65 IntVector loc = chunk2UseIndex.get(bc);
66 if (loc == null) {
67 chunk2UseIndex.put(bc, loc = new IntVector());
68 }
69 loc.add(i);
70 // bc.registerUseIn(i) - BEWARE, use of bc here is incorrect
71 // in this case need to find the only ByteChain to keep indexes
72 // i.e. when there are few equal ByteChain instances, notion of "usedIn" shall be either shared (reference same vector)
73 // or kept within only one of them
74 }
75 // for (ChunkSequence.ByteChain bc : chunk2UseIndex.keySet()) {
76 // System.out.printf("%s: {", new String(bc.data()));
77 // for (int x : chunk2UseIndex.get(bc).toArray()) {
78 // System.out.printf(" %d,", x);
79 // }
80 // System.out.println("}");
81 // }
82 }
83
84 public void findMatchingBlocks() {
85 changeStartS1 = changeStartS2 = 0;
86 findMatchingBlocks(0, seq1.chunkCount(), 0, seq2.chunkCount());
87 if (changeStartS1 < seq1.chunkCount() || changeStartS2 < seq2.chunkCount()) {
88 reportDeltaElement(seq1.chunkCount(), seq2.chunkCount());
89 }
90 }
91
92 /**
93 * implementation based on Python's difflib.py and SequenceMatcher
94 */
95 public int longestMatch(int startS1, int endS1, int startS2, int endS2) {
96 matchStartS1 = matchStartS2 = 0;
97 int maxLength = 0;
98 IntMap<Integer> chunkIndex2MatchCount = new IntMap<Integer>(8);
99 for (int i = startS1; i < endS1; i++) {
100 ChunkSequence.ByteChain bc = seq1.chunk(i);
101 IntMap<Integer> newChunkIndex2MatchCount = new IntMap<Integer>(8);
102 IntVector occurencesInS2 = chunk2UseIndex.get(bc);
103 if (occurencesInS2 == null) {
104 // chunkIndex2MatchCount.clear(); // TODO need clear instead of new instance
105 chunkIndex2MatchCount = newChunkIndex2MatchCount;
106 continue;
107 }
108 for (int j : occurencesInS2.toArray()) {
109 // s1[i] == s2[j]
110 if (j < startS2) {
111 continue;
112 }
113 if (j >= endS2) {
114 break;
115 }
116 int prevChunkMatches = chunkIndex2MatchCount.containsKey(j-1) ? chunkIndex2MatchCount.get(j-1) : 0;
117 int k = prevChunkMatches + 1;
118 newChunkIndex2MatchCount.put(j, k);
119 if (k > maxLength) {
120 matchStartS1 = i-k+1;
121 matchStartS2 = j-k+1;
122 maxLength = k;
123 }
124 }
125 chunkIndex2MatchCount = newChunkIndex2MatchCount;
126 }
127 return maxLength;
128 }
129
130 public void findMatchingBlocks(int startS1, int endS1, int startS2, int endS2) {
131 int matchLength = longestMatch(startS1, endS1, startS2, endS2);
132 if (matchLength > 0) {
133 final int saveStartS1 = matchStartS1, saveStartS2 = matchStartS2;
134 if (startS1 < matchStartS1 && startS2 < matchStartS2) {
135 findMatchingBlocks(startS1, matchStartS1, startS2, matchStartS2);
136 }
137 reportDeltaElement(saveStartS1, saveStartS2);
138 changeStartS1 = saveStartS1 + matchLength;
139 changeStartS2 = saveStartS2 + matchLength;
140 // System.out.printf("match: from line #%d and line #%d of length %d\n", saveStartS1, saveStartS2, matchLength);
141 if (saveStartS1+matchLength < endS1 && saveStartS2+matchLength < endS2) {
142 findMatchingBlocks(saveStartS1 + matchLength, endS1, saveStartS2 + matchLength, endS2);
143 }
144 }
145 }
146
147 private Patch deltaCollector;
148
149 private void reportDeltaElement(int i, int j) {
150 if (changeStartS1 < i) {
151 if (changeStartS2 < j) {
152 System.out.printf("changed [%d..%d) with [%d..%d)\n", changeStartS1, i, changeStartS2, j);
153 } else {
154 assert changeStartS2 == j;
155 System.out.printf("deleted [%d..%d)\n", changeStartS1, i);
156 }
157 if (deltaCollector != null) {
158 int from = seq1.chunk(changeStartS1).getOffset();
159 int to = seq1.chunk(i).getOffset();
160 byte[] data = seq2.data(changeStartS2, j);
161 deltaCollector.add(from, to, data);
162 }
163 } else {
164 assert changeStartS1 == i;
165 if(changeStartS2 < j) {
166 System.out.printf("added [%d..%d)\n", changeStartS2, j);
167 } else {
168 assert changeStartS2 == j;
169 System.out.printf("adjustent equal blocks %d, %d and %d,%d\n", changeStartS1, i, changeStartS2, j);
170 }
171 if (deltaCollector != null) {
172 int insPoint = seq1.chunk(changeStartS1).getOffset();
173 byte[] data = seq2.data(changeStartS2, j);
174 deltaCollector.add(insPoint, insPoint, data);
175 }
176 }
177 }
178
179 public static void main(String[] args) throws Exception {
180 HgRepository repo = new HgLookup().detectFromWorkingDir();
181 HgDataFile df = repo.getFileNode("cmdline/org/tmatesoft/hg/console/Main.java");
182 ByteArrayChannel bac1, bac2;
183 df.content(80, bac1 = new ByteArrayChannel());
184 df.content(81, bac2 = new ByteArrayChannel());
185 // String s1 = "line 1\nline 2\r\nline 3\n\nline 1\nline 2";
186 // String s2 = "abc\ncdef\r\nline 2\r\nline 3\nline 2";
187 PatchGenerator pg = new PatchGenerator();
188 pg.init(bac1.toArray(), bac2.toArray());
189 pg.findMatchingBlocks();
190 }
191
192 public Patch delta(byte[] prev, byte[] content) {
193 deltaCollector = new Patch();
194 init(prev, content);
195 findMatchingBlocks();
196 return deltaCollector;
197 }
198
199 private static class ChunkSequence {
200
201 private final byte[] input;
202 private ArrayList<ByteChain> lines;
203
204 public ChunkSequence(byte[] data) {
205 input = data;
206 }
207
208 public void splitByNewlines() {
209 lines = new ArrayList<ByteChain>();
210 int lastStart = 0;
211 for (int i = 0; i < input.length; i++) {
212 if (input[i] == '\n') {
213 lines.add(new ByteChain(lastStart, i+1));
214 lastStart = i+1;
215 } else if (input[i] == '\r') {
216 if (i+1 < input.length && input[i+1] == '\n') {
217 i++;
218 }
219 lines.add(new ByteChain(lastStart, i+1));
220 lastStart = i+1;
221 }
222 }
223 if (lastStart < input.length) {
224 lines.add(new ByteChain(lastStart, input.length));
225 }
226 }
227
228 public ByteChain chunk(int index) {
229 return lines.get(index);
230 }
231
232 public int chunkCount() {
233 return lines.size();
234 }
235
236 public byte[] data(int chunkFrom, int chunkTo) {
237 if (chunkFrom == chunkTo) {
238 return new byte[0];
239 }
240 int from = chunk(chunkFrom).getOffset(), to = chunk(chunkTo).getOffset();
241 byte[] rv = new byte[to - from];
242 System.arraycopy(input, from, rv, 0, rv.length);
243 return rv;
244 }
245
246
247 final class ByteChain {
248 private final int start, end;
249 private final int hash;
250
251 ByteChain(int s, int e) {
252 start = s;
253 end = e;
254 hash = calcHash(input, s, e);
255 }
256
257 /**
258 * byte offset of the this ByteChain inside ChainSequence
259 */
260 public int getOffset() {
261 return start;
262 }
263
264 public byte[] data() {
265 byte[] rv = new byte[end - start];
266 System.arraycopy(input, start, rv, 0, rv.length);
267 return rv;
268 }
269
270 @Override
271 public boolean equals(Object obj) {
272 if (obj == null || obj.getClass() != ByteChain.class) {
273 return false;
274 }
275 ByteChain other = (ByteChain) obj;
276 if (other.hash != hash || other.end - other.start != end - start) {
277 return false;
278 }
279 return other.match(input, start);
280 }
281
282 private boolean match(byte[] oi, int from) {
283 for (int i = start, j = from; i < end; i++, j++) {
284 if (ChunkSequence.this.input[i] != oi[j]) {
285 return false;
286 }
287 }
288 return true;
289 }
290
291 @Override
292 public int hashCode() {
293 return hash;
294 }
295
296 @Override
297 public String toString() {
298 return String.format("[@%d\"%s\"]", start, new String(data()));
299 }
300 }
301
302 // same as Arrays.hashCode(byte[]), just for a slice of a bigger array
303 static int calcHash(byte[] data, int from, int to) {
304 int result = 1;
305 for (int i = from; i < to; i++) {
306 result = 31 * result + data[i];
307 }
308 return result;
309 }
310 }
311 }