tikhomirov@533: /*
tikhomirov@533:  * Copyright (c) 2013 TMate Software Ltd
tikhomirov@533:  *  
tikhomirov@533:  * This program is free software; you can redistribute it and/or modify
tikhomirov@533:  * it under the terms of the GNU General Public License as published by
tikhomirov@533:  * the Free Software Foundation; version 2 of the License.
tikhomirov@533:  *
tikhomirov@533:  * This program is distributed in the hope that it will be useful,
tikhomirov@533:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
tikhomirov@533:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
tikhomirov@533:  * GNU General Public License for more details.
tikhomirov@533:  *
tikhomirov@533:  * For information on how to redistribute this software under
tikhomirov@533:  * the terms of a license other than GNU General Public License
tikhomirov@533:  * contact TMate Software at support@hg4j.com
tikhomirov@533:  */
tikhomirov@533: package org.tmatesoft.hg.internal;
tikhomirov@533: 
tikhomirov@533: import java.util.ArrayList;
tikhomirov@533: import java.util.HashMap;
tikhomirov@533: import java.util.Map;
tikhomirov@533: 
tikhomirov@549: import org.tmatesoft.hg.repo.HgInvalidStateException;
tikhomirov@533: 
tikhomirov@533: /**
tikhomirov@538:  * Mercurial cares about changes only up to the line level, e.g. a simple file version dump in manifest looks like (RevlogDump output):
tikhomirov@533:  * 
tikhomirov@533:  *   522:        233748      0        103      17438        433        522      521       -1     756073cf2321df44d3ed0585f2a5754bc8a1b2f6
tikhomirov@533:  *   <PATCH>:
tikhomirov@533:  *   3487..3578, 91:src/org/tmatesoft/hg/core/HgIterateDirection.java\00add61a8a665c5d8f092210767f812fe0d335ac8
tikhomirov@533:  *   
tikhomirov@533:  * I.e. for the {fname}{revision} entry format of manifest, not only {revision} is changed, but the whole line, with unchanged {fname} is recorded
tikhomirov@533:  * in the patch.
tikhomirov@533:  * 
tikhomirov@533:  * Mercurial paper describes reasons for choosing this approach to delta generation, too.
tikhomirov@533:  * 
tikhomirov@533:  * 
tikhomirov@533:  * @author Artem Tikhomirov
tikhomirov@533:  * @author TMate Software Ltd.
tikhomirov@533:  */
tikhomirov@551: public class DiffHelper<T extends DiffHelper.ChunkSequence<?>> {
tikhomirov@533: 
tikhomirov@551: 	private Map<Object, IntVector> chunk2UseIndex;
tikhomirov@544: 	private T seq1, seq2;
tikhomirov@533: 
tikhomirov@533: 	// get filled by #longestMatch, track start of common sequence in seq1 and seq2, respectively
tikhomirov@533: 	private int matchStartS1, matchStartS2;
tikhomirov@541: 
tikhomirov@544: 	private MatchInspector<T> matchInspector; 
tikhomirov@533: 
tikhomirov@544: 	public void init(T s1, T s2) {
tikhomirov@544: 		seq1 = s1;
tikhomirov@544: 		seq2 = s2;
tikhomirov@544: 		prepare(s2);
tikhomirov@533: 	}
tikhomirov@549: 	
tikhomirov@549: 	public void init(T s1) {
tikhomirov@549: 		if (seq2 == null) {
tikhomirov@549: 			throw new IllegalStateException("Use this #init() only when target sequence shall be matched against different origin");
tikhomirov@549: 		}
tikhomirov@549: 		seq1 = s1;
tikhomirov@549: 	}
tikhomirov@533: 
tikhomirov@544: 
tikhomirov@544: 	private void prepare(T s2) {
tikhomirov@551: 		chunk2UseIndex = new HashMap<Object, IntVector>();
tikhomirov@533: 		for (int i = 0, len = s2.chunkCount(); i < len; i++) {
tikhomirov@551: 			Object bc = s2.chunk(i);
tikhomirov@533: 			IntVector loc = chunk2UseIndex.get(bc);
tikhomirov@533: 			if (loc == null) {
tikhomirov@533: 				chunk2UseIndex.put(bc, loc = new IntVector());
tikhomirov@533: 			}
tikhomirov@533: 			loc.add(i);
tikhomirov@533: 			// bc.registerUseIn(i) - BEWARE, use of bc here is incorrect
tikhomirov@533: 			// in this case need to find the only ByteChain to keep indexes
tikhomirov@533: 			// i.e. when there are few equal ByteChain instances, notion of "usedIn" shall be either shared (reference same vector)
tikhomirov@533: 			// or kept within only one of them
tikhomirov@533: 		}
tikhomirov@533: 	}
tikhomirov@533: 	
tikhomirov@544: 	public void findMatchingBlocks(MatchInspector<T> insp) {
tikhomirov@541: 		insp.begin(seq1, seq2);
tikhomirov@541: 		matchInspector = insp;
tikhomirov@533: 		findMatchingBlocks(0, seq1.chunkCount(), 0, seq2.chunkCount());
tikhomirov@541: 		insp.end();
tikhomirov@533: 	}
tikhomirov@533: 	
tikhomirov@533: 	/**
tikhomirov@533: 	 * implementation based on Python's difflib.py and SequenceMatcher 
tikhomirov@533: 	 */
tikhomirov@533: 	public int longestMatch(int startS1, int endS1, int startS2, int endS2) {
tikhomirov@533: 		matchStartS1 = matchStartS2 = 0;
tikhomirov@533: 		int maxLength = 0;
tikhomirov@533: 		IntMap<Integer> chunkIndex2MatchCount = new IntMap<Integer>(8);
tikhomirov@533: 		for (int i = startS1; i < endS1; i++) {
tikhomirov@551: 			Object bc = seq1.chunk(i);
tikhomirov@533: 			IntVector occurencesInS2 = chunk2UseIndex.get(bc);
tikhomirov@533: 			if (occurencesInS2 == null) {
tikhomirov@551: 				chunkIndex2MatchCount.clear();
tikhomirov@533: 				continue;
tikhomirov@533: 			}
tikhomirov@551: 			IntMap<Integer> newChunkIndex2MatchCount = new IntMap<Integer>(8);
tikhomirov@533: 			for (int j : occurencesInS2.toArray()) {
tikhomirov@533: 				// s1[i] == s2[j]
tikhomirov@533: 				if (j < startS2) {
tikhomirov@533: 					continue;
tikhomirov@533: 				}
tikhomirov@533: 				if (j >= endS2) {
tikhomirov@533: 					break;
tikhomirov@533: 				}
tikhomirov@533: 				int prevChunkMatches = chunkIndex2MatchCount.containsKey(j-1) ? chunkIndex2MatchCount.get(j-1) : 0;
tikhomirov@533: 				int k = prevChunkMatches + 1;
tikhomirov@533: 				newChunkIndex2MatchCount.put(j, k);
tikhomirov@533: 				if (k > maxLength) {
tikhomirov@533: 					matchStartS1 = i-k+1;
tikhomirov@533: 					matchStartS2 = j-k+1;
tikhomirov@533: 					maxLength = k;
tikhomirov@533: 				}
tikhomirov@533: 			}
tikhomirov@533: 			chunkIndex2MatchCount = newChunkIndex2MatchCount;
tikhomirov@533: 		}
tikhomirov@533: 		return maxLength;
tikhomirov@533: 	}
tikhomirov@533: 	
tikhomirov@541: 	private void findMatchingBlocks(int startS1, int endS1, int startS2, int endS2) {
tikhomirov@533: 		int matchLength = longestMatch(startS1, endS1, startS2, endS2);
tikhomirov@533: 		if (matchLength > 0) {
tikhomirov@533: 			final int saveStartS1 = matchStartS1, saveStartS2 = matchStartS2;
tikhomirov@533: 			if (startS1 < matchStartS1 && startS2 < matchStartS2) {
tikhomirov@533: 				findMatchingBlocks(startS1, matchStartS1, startS2, matchStartS2);
tikhomirov@533: 			}
tikhomirov@541: 			matchInspector.match(saveStartS1, saveStartS2, matchLength);
tikhomirov@533: 			if (saveStartS1+matchLength < endS1 && saveStartS2+matchLength < endS2) {
tikhomirov@533: 				findMatchingBlocks(saveStartS1 + matchLength, endS1, saveStartS2 + matchLength, endS2);
tikhomirov@533: 			}
tikhomirov@533: 		}
tikhomirov@533: 	}
tikhomirov@533: 	
tikhomirov@551: 	public interface MatchInspector<T extends ChunkSequence<?>> {
tikhomirov@544: 		void begin(T s1, T s2);
tikhomirov@541: 		void match(int startSeq1, int startSeq2, int matchLength);
tikhomirov@541: 		void end();
tikhomirov@541: 	}
tikhomirov@533: 	
tikhomirov@544: 	static class MatchDumpInspector<T extends ChunkSequence<?>> implements MatchInspector<T> {
tikhomirov@545: 		private int matchCount;
tikhomirov@545: 
tikhomirov@544: 		public void begin(T s1, T s2) {
tikhomirov@545: 			matchCount = 0;
tikhomirov@541: 		}
tikhomirov@541: 
tikhomirov@541: 		public void match(int startSeq1, int startSeq2, int matchLength) {
tikhomirov@545: 			matchCount++;
tikhomirov@545: 			System.out.printf("match #%d: from line #%d  and line #%d of length %d\n", matchCount, startSeq1, startSeq2, matchLength);
tikhomirov@541: 		}
tikhomirov@541: 
tikhomirov@541: 		public void end() {
tikhomirov@545: 			if (matchCount == 0) {
tikhomirov@545: 				System.out.println("NO MATCHES FOUND!");
tikhomirov@545: 			}
tikhomirov@541: 		}
tikhomirov@541: 	}
tikhomirov@541: 	
tikhomirov@551: 	/**
tikhomirov@551: 	 * Matcher implementation that translates "match/equal" notification to a delta-style "added/removed/changed". 
tikhomirov@551: 	 */
tikhomirov@551: 	public static class DeltaInspector<T extends ChunkSequence<?>> implements MatchInspector<T> {
tikhomirov@541: 		protected int changeStartS1, changeStartS2;
tikhomirov@544: 		protected T seq1, seq2;
tikhomirov@541: 
tikhomirov@544: 		public void begin(T s1, T s2) {
tikhomirov@541: 			seq1 = s1;
tikhomirov@541: 			seq2 = s2;
tikhomirov@541: 			changeStartS1 = changeStartS2 = 0;
tikhomirov@541: 		}
tikhomirov@541: 
tikhomirov@541: 		public void match(int startSeq1, int startSeq2, int matchLength) {
tikhomirov@542: 			reportDeltaElement(startSeq1, startSeq2, matchLength);
tikhomirov@541: 			changeStartS1 = startSeq1 + matchLength;
tikhomirov@541: 			changeStartS2 = startSeq2 + matchLength;
tikhomirov@541: 		}
tikhomirov@541: 
tikhomirov@541: 		public void end() {
tikhomirov@545: 			if (changeStartS1 < seq1.chunkCount()-1 || changeStartS2 < seq2.chunkCount()-1) {
tikhomirov@545: 				reportDeltaElement(seq1.chunkCount()-1, seq2.chunkCount()-1, 0);
tikhomirov@541: 			}
tikhomirov@541: 		}
tikhomirov@541: 
tikhomirov@542: 		protected void reportDeltaElement(int matchStartSeq1, int matchStartSeq2, int matchLength) {
tikhomirov@541: 			if (changeStartS1 < matchStartSeq1) {
tikhomirov@541: 				if (changeStartS2 < matchStartSeq2) {
tikhomirov@542: 					changed(changeStartS1, matchStartSeq1, changeStartS2, matchStartSeq2);
tikhomirov@541: 				} else {
tikhomirov@541: 					assert changeStartS2 == matchStartSeq2;
tikhomirov@543: 					deleted(matchStartSeq2, changeStartS1, matchStartSeq1);
tikhomirov@541: 				}
tikhomirov@533: 			} else {
tikhomirov@541: 				assert changeStartS1 == matchStartSeq1;
tikhomirov@541: 				if(changeStartS2 < matchStartSeq2) {
tikhomirov@545: 					added(changeStartS1, changeStartS2, matchStartSeq2);
tikhomirov@541: 				} else {
tikhomirov@541: 					assert changeStartS2 == matchStartSeq2;
tikhomirov@549: 					if (matchStartSeq1 > 0 || matchStartSeq2 > 0) {
tikhomirov@549: 						// FIXME perhaps, exception is too much for the case
tikhomirov@549: 						// once diff is covered with tests, replace with assert false : msg; 
tikhomirov@549: 						throw new HgInvalidStateException(String.format("adjustent equal blocks %d, %d and %d,%d", changeStartS1, matchStartSeq1, changeStartS2, matchStartSeq2));
tikhomirov@549: 					}
tikhomirov@541: 				}
tikhomirov@533: 			}
tikhomirov@542: 			if (matchLength > 0) {
tikhomirov@542: 				unchanged(matchStartSeq1, matchStartSeq2, matchLength);
tikhomirov@542: 			}
tikhomirov@542: 		}
tikhomirov@542: 
tikhomirov@542: 		/**
tikhomirov@542: 		 * [s1From..s1To) replaced with [s2From..s2To)
tikhomirov@542: 		 */
tikhomirov@542: 		protected void changed(int s1From, int s1To, int s2From, int s2To) {
tikhomirov@542: 			// NO-OP
tikhomirov@542: 		}
tikhomirov@542: 
tikhomirov@543: 		protected void deleted(int s2DeletePoint, int s1From, int s1To) {
tikhomirov@542: 			// NO-OP
tikhomirov@542: 		}
tikhomirov@542: 
tikhomirov@542: 		protected void added(int s1InsertPoint, int s2From, int s2To) {
tikhomirov@542: 			// NO-OP
tikhomirov@542: 		}
tikhomirov@542: 
tikhomirov@542: 		protected void unchanged(int s1From, int s2From, int length) {
tikhomirov@542: 			// NO-OP
tikhomirov@541: 		}
tikhomirov@541: 	}
tikhomirov@541: 	
tikhomirov@583: 	public static class DeltaDumpInspector<T extends ChunkSequence<?>> extends DeltaInspector<T> {
tikhomirov@542: 
tikhomirov@542: 		@Override
tikhomirov@542: 		protected void changed(int s1From, int s1To, int s2From, int s2To) {
tikhomirov@542: 			System.out.printf("changed [%d..%d) with [%d..%d)\n", s1From, s1To, s2From, s2To);
tikhomirov@542: 		}
tikhomirov@542: 		
tikhomirov@542: 		@Override
tikhomirov@543: 		protected void deleted(int s2DeletionPoint, int s1From, int s1To) {
tikhomirov@542: 			System.out.printf("deleted [%d..%d)\n", s1From, s1To);
tikhomirov@542: 		}
tikhomirov@542: 		
tikhomirov@542: 		@Override
tikhomirov@542: 		protected void added(int s1InsertPoint, int s2From, int s2To) {
tikhomirov@542: 			System.out.printf("added [%d..%d) at %d\n", s2From, s2To, s1InsertPoint);
tikhomirov@542: 		}
tikhomirov@545: 
tikhomirov@545: 		@Override
tikhomirov@545: 		protected void unchanged(int s1From, int s2From, int length) {
tikhomirov@545: 			System.out.printf("same [%d..%d) and [%d..%d)\n", s1From, s1From + length, s2From, s2From + length);
tikhomirov@545: 		}
tikhomirov@542: 	}
tikhomirov@542: 	
tikhomirov@544: 	/**
tikhomirov@544: 	 * Generic sequence of chunk, where chunk is anything comparable to another chunk, e.g. a string or a single char
tikhomirov@544: 	 * Sequence diff algorithm above doesn't care about sequence nature.
tikhomirov@544: 	 */
tikhomirov@551: 	public interface ChunkSequence<T> {
tikhomirov@544: 		public T chunk(int index);
tikhomirov@544: 		public int chunkCount();
tikhomirov@533: 	}
tikhomirov@533: 	
tikhomirov@551: 	public static final class LineSequence implements ChunkSequence<LineSequence.ByteChain> {
tikhomirov@533: 		
tikhomirov@533: 		private final byte[] input;
tikhomirov@533: 		private ArrayList<ByteChain> lines;
tikhomirov@533: 
tikhomirov@544: 		public LineSequence(byte[] data) {
tikhomirov@533: 			input = data;
tikhomirov@533: 		}
tikhomirov@533: 		
tikhomirov@544: 		public static LineSequence newlines(byte[] array) {
tikhomirov@544: 			return new LineSequence(array).splitByNewlines();
tikhomirov@544: 		}
tikhomirov@544: 
tikhomirov@545: 		// sequence ends with fake, empty line chunk
tikhomirov@544: 		public LineSequence splitByNewlines() {
tikhomirov@533: 			lines = new ArrayList<ByteChain>();
tikhomirov@533: 			int lastStart = 0;
tikhomirov@533: 			for (int i = 0; i < input.length; i++) {
tikhomirov@533: 				if (input[i] == '\n') {
tikhomirov@533: 					lines.add(new ByteChain(lastStart, i+1));
tikhomirov@533: 					lastStart = i+1;
tikhomirov@533: 				} else if (input[i] == '\r') {
tikhomirov@533: 					if (i+1 < input.length && input[i+1] == '\n') {
tikhomirov@533: 						i++;
tikhomirov@533: 					}
tikhomirov@533: 					lines.add(new ByteChain(lastStart, i+1));
tikhomirov@533: 					lastStart = i+1;
tikhomirov@533: 				}
tikhomirov@533: 			}
tikhomirov@533: 			if (lastStart < input.length) {
tikhomirov@533: 				lines.add(new ByteChain(lastStart, input.length));
tikhomirov@533: 			}
tikhomirov@538: 			// empty chunk to keep offset of input end
tikhomirov@545: 			lines.add(new ByteChain(input.length));
tikhomirov@544: 			return this;
tikhomirov@533: 		}
tikhomirov@533: 		
tikhomirov@533: 		public ByteChain chunk(int index) {
tikhomirov@533: 			return lines.get(index);
tikhomirov@533: 		}
tikhomirov@533: 		
tikhomirov@533: 		public int chunkCount() {
tikhomirov@533: 			return lines.size();
tikhomirov@533: 		}
tikhomirov@533: 		
tikhomirov@533: 		public byte[] data(int chunkFrom, int chunkTo) {
tikhomirov@533: 			if (chunkFrom == chunkTo) {
tikhomirov@533: 				return new byte[0];
tikhomirov@533: 			}
tikhomirov@533: 			int from = chunk(chunkFrom).getOffset(), to = chunk(chunkTo).getOffset();
tikhomirov@533: 			byte[] rv = new byte[to - from];
tikhomirov@533: 			System.arraycopy(input, from, rv, 0, rv.length);
tikhomirov@533: 			return rv;
tikhomirov@533: 		}
tikhomirov@533: 
tikhomirov@533: 		
tikhomirov@556: 		public final class ByteChain {
tikhomirov@533: 			private final int start, end;
tikhomirov@533: 			private final int hash;
tikhomirov@533: 			
tikhomirov@545: 			/**
tikhomirov@545: 			 * construct a chunk with a sole purpose to keep 
tikhomirov@545: 			 * offset of the data end
tikhomirov@545: 			 */
tikhomirov@545: 			ByteChain(int offset) {
tikhomirov@545: 				start = end = offset;
tikhomirov@545: 				// ensure this chunk doesn't match trailing chunk of another sequence
tikhomirov@545: 				hash = System.identityHashCode(this);
tikhomirov@545: 			}
tikhomirov@545: 			
tikhomirov@533: 			ByteChain(int s, int e) {
tikhomirov@533: 				start = s;
tikhomirov@533: 				end = e;
tikhomirov@533: 				hash = calcHash(input, s, e);
tikhomirov@533: 			}
tikhomirov@533: 			
tikhomirov@533: 			/**
tikhomirov@533: 			 * byte offset of the this ByteChain inside ChainSequence 
tikhomirov@533: 			 */
tikhomirov@533: 			public int getOffset() {
tikhomirov@533: 				return start;
tikhomirov@533: 			}
tikhomirov@533: 			
tikhomirov@533: 			public byte[] data() {
tikhomirov@533: 				byte[] rv = new byte[end - start];
tikhomirov@533: 				System.arraycopy(input, start, rv, 0, rv.length);
tikhomirov@533: 				return rv;
tikhomirov@533: 			}
tikhomirov@533: 			
tikhomirov@533: 			@Override
tikhomirov@533: 			public boolean equals(Object obj) {
tikhomirov@533: 				if (obj == null || obj.getClass() != ByteChain.class) {
tikhomirov@533: 					return false;
tikhomirov@533: 				}
tikhomirov@533: 				ByteChain other = (ByteChain) obj;
tikhomirov@533: 				if (other.hash != hash || other.end - other.start != end - start) {
tikhomirov@533: 					return false;
tikhomirov@533: 				}
tikhomirov@533: 				return other.match(input, start);
tikhomirov@533: 			}
tikhomirov@533: 			
tikhomirov@533: 			private boolean match(byte[] oi, int from) {
tikhomirov@533: 				for (int i = start, j = from; i < end; i++, j++) {
tikhomirov@544: 					if (LineSequence.this.input[i] != oi[j]) {
tikhomirov@533: 						return false;
tikhomirov@533: 					}
tikhomirov@533: 				}
tikhomirov@533: 				return true;
tikhomirov@533: 			}
tikhomirov@533: 			
tikhomirov@533: 			@Override
tikhomirov@533: 			public int hashCode() {
tikhomirov@533: 				return hash;
tikhomirov@533: 			}
tikhomirov@533: 			
tikhomirov@533: 			@Override
tikhomirov@533: 			public String toString() {
tikhomirov@533: 				return String.format("[@%d\"%s\"]", start, new String(data()));
tikhomirov@533: 			}
tikhomirov@533: 		}
tikhomirov@533: 
tikhomirov@533: 		// same as Arrays.hashCode(byte[]), just for a slice of a bigger array
tikhomirov@533: 		static int calcHash(byte[] data, int from, int to) {
tikhomirov@533: 			int result = 1;
tikhomirov@533: 			for (int i = from; i < to; i++) {
tikhomirov@533: 				result = 31 * result + data[i];
tikhomirov@533: 			}
tikhomirov@533: 			return result;
tikhomirov@533: 		}
tikhomirov@533: 	}
tikhomirov@533: }