--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/diff/BlameHelper.java	Wed Aug 14 14:51:51 2013 +0200
@@ -0,0 +1,972 @@
+/*
+ * Copyright (c) 2013 TMate Software Ltd
+ *  
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@hg4j.com
+ */
+package org.tmatesoft.hg.internal.diff;
+
+import static org.tmatesoft.hg.core.HgIterateDirection.OldToNew;
+import static org.tmatesoft.hg.repo.HgRepository.NO_REVISION;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.ListIterator;
+
+import org.tmatesoft.hg.core.HgCallbackTargetException;
+import org.tmatesoft.hg.core.Nodeid;
+import org.tmatesoft.hg.internal.ByteArrayChannel;
+import org.tmatesoft.hg.internal.FileHistory;
+import org.tmatesoft.hg.internal.FileRevisionHistoryChunk;
+import org.tmatesoft.hg.internal.IntSliceSeq;
+import org.tmatesoft.hg.internal.IntTuple;
+import org.tmatesoft.hg.internal.IntVector;
+import org.tmatesoft.hg.internal.diff.DiffHelper.LineSequence;
+import org.tmatesoft.hg.internal.diff.DiffHelper.LineSequence.ByteChain;
+import org.tmatesoft.hg.internal.diff.DiffRangeMap.RangePair;
+import org.tmatesoft.hg.core.HgBlameInspector;
+import org.tmatesoft.hg.core.HgBlameInspector.*;
+import org.tmatesoft.hg.repo.HgChangelog;
+import org.tmatesoft.hg.repo.HgDataFile;
+import org.tmatesoft.hg.repo.HgInvalidStateException;
+import org.tmatesoft.hg.repo.HgParentChildMap;
+import org.tmatesoft.hg.repo.HgRepository;
+import org.tmatesoft.hg.repo.HgRevisionMap;
+import org.tmatesoft.hg.repo.HgRuntimeException;
+import org.tmatesoft.hg.util.Adaptable;
+import org.tmatesoft.hg.util.CancelledException;
+import org.tmatesoft.hg.util.Pair;
+
+/**
+ * Blame implementation
+ * @see HgBlameInspector
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public class BlameHelper {
+	
+	private final HgBlameInspector insp;
+	private FileLinesCache linesCache;
+	private HgParentChildMap<HgChangelog> clogMap;
+
+	public BlameHelper(HgBlameInspector inspector) {
+		insp = inspector;
+	}
+
+	/**
+	 * Build history of the file for the specified range (follow renames if necessary). This history
+	 * is used to access various file revision data during subsequent {@link #diff(int, int, int, int)} and
+	 * {@link #annotateChange(int, int, int[], int[])} calls. Callers can use returned history for own approaches 
+	 * to iteration over file history.
+
+	 * <p>NOTE, clogRevIndexEnd has to list name of the supplied file in the corresponding manifest,
+	 * as it's not possible to trace rename history otherwise.
+	 */
+	public FileHistory prepare(HgDataFile df, int clogRevIndexStart, int clogRevIndexEnd) throws HgRuntimeException {
+		assert clogRevIndexStart <= clogRevIndexEnd;
+		FileHistory fileHistory = new FileHistory(df, clogRevIndexStart, clogRevIndexEnd);
+		fileHistory.build();
+		int cacheHint = 5; // cache comes useful when we follow merge branches and don't want to
+		// parse base revision twice. There's no easy way to determine max(distance(all(base,merge))),
+		// hence the heuristics to use the longest history chunk:
+		for (FileRevisionHistoryChunk c : fileHistory.iterate(OldToNew)) {
+			// iteration order is not important here
+			if (c.revisionCount() > cacheHint) {
+				cacheHint = c.revisionCount();
+			}
+		}
+		linesCache = new FileLinesCache(cacheHint);
+		for (FileRevisionHistoryChunk fhc : fileHistory.iterate(OldToNew)) {
+			// iteration order is not important here
+			linesCache.useFileUpTo(fhc.getFile(), fhc.getEndChangeset());
+		}
+		return fileHistory;
+	}
+	
+	// NO_REVISION is not allowed as any argument
+	public void diff(int fileRevIndex1, int clogRevIndex1, int fileRevIndex2, int clogRevIndex2) throws HgCallbackTargetException, HgRuntimeException {
+		HgDataFile targetFile = linesCache.getFile(clogRevIndex2);
+		LineSequence c1 = linesCache.lines(clogRevIndex1, fileRevIndex1);
+		LineSequence c2 = linesCache.lines(clogRevIndex2, fileRevIndex2);
+		DiffHelper<LineSequence> pg = new DiffHelper<LineSequence>();
+		pg.init(c1, c2);
+		BlameBlockInspector bbi = new BlameBlockInspector(targetFile, fileRevIndex2, insp, clogRevIndex1, clogRevIndex2);
+		pg.findMatchingBlocks(bbi);
+		bbi.checkErrors();
+	}
+
+	public void annotateChange(int fileRevIndex, int csetRevIndex, int[] fileParentRevs, int[] fileParentClogRevs) throws HgCallbackTargetException, HgRuntimeException {
+		HgDataFile targetFile = linesCache.getFile(csetRevIndex);
+		final LineSequence fileRevLines = linesCache.lines(csetRevIndex, fileRevIndex);
+		if (fileParentClogRevs[0] != NO_REVISION && fileParentClogRevs[1] != NO_REVISION) {
+			int p1ClogIndex = fileParentClogRevs[0];
+			int p2ClogIndex = fileParentClogRevs[1];
+			LineSequence p1Lines = linesCache.lines(p1ClogIndex, fileParentRevs[0]);
+			LineSequence p2Lines = linesCache.lines(p2ClogIndex, fileParentRevs[1]);
+			MergeResolutionStrategy mergeResolver = createMergeStrategy(fileRevLines, p1Lines, p2Lines, csetRevIndex, fileParentClogRevs);
+			//
+			DiffHelper<LineSequence> pg = new DiffHelper<LineSequence>();
+			pg.init(p1Lines, fileRevLines);
+			BlameBlockInspector bbi = new BlameBlockInspector(targetFile, fileRevIndex, insp, p1ClogIndex, csetRevIndex);
+			bbi.setMergeParent2(mergeResolver, p2ClogIndex);
+			pg.findMatchingBlocks(bbi);
+			bbi.checkErrors();
+		} else if (fileParentClogRevs[0] == fileParentClogRevs[1]) {
+			// may be equal iff both are unset
+			assert fileParentClogRevs[0] == NO_REVISION;
+			// everything added
+			BlameBlockInspector bbi = new BlameBlockInspector(targetFile, fileRevIndex, insp, NO_REVISION, csetRevIndex);
+			bbi.begin(LineSequence.newlines(new byte[0]), fileRevLines);
+			bbi.match(0, fileRevLines.chunkCount()-1, 0);
+			bbi.end();
+			bbi.checkErrors();
+		} else {
+			int soleParentIndex = fileParentClogRevs[0] == NO_REVISION ? 1 : 0;
+			assert fileParentClogRevs[soleParentIndex] != NO_REVISION;
+			LineSequence parentLines = linesCache.lines(fileParentClogRevs[soleParentIndex], fileParentRevs[soleParentIndex]);
+			
+			DiffHelper<LineSequence> pg = new DiffHelper<LineSequence>();
+			pg.init(parentLines, fileRevLines);
+			BlameBlockInspector bbi = new BlameBlockInspector(targetFile, fileRevIndex, insp, fileParentClogRevs[soleParentIndex], csetRevIndex);
+			pg.findMatchingBlocks(bbi);
+			bbi.checkErrors();
+		}
+	}
+	
+	private static final boolean useNewStrategy = Boolean.TRUE.booleanValue();
+	
+	private MergeResolutionStrategy createMergeStrategy(LineSequence fileRevLines, LineSequence p1Lines, LineSequence p2Lines, int csetRevIndex, int[] fileParentClogRevs) {
+		DiffHelper<LineSequence> pg = new DiffHelper<LineSequence>();
+		if (useNewStrategy) {
+			final ArrayList<RangePairSeq> allMatches = new ArrayList<RangePairSeq>();
+			pg.init(p2Lines, fileRevLines);
+			pg.findAllMatchAlternatives(new DiffHelper.MatchInspector<LineSequence>() {
+				private RangePairSeq matches;
+
+				public void begin(LineSequence s1, LineSequence s2) {
+					matches = new RangePairSeq();
+				}
+
+				public void match(int startSeq1, int startSeq2, int matchLength) {
+					matches.add(startSeq1, startSeq2, matchLength);
+				}
+
+				public void end() {
+					if (matches.size() > 0) {
+						allMatches.add(matches);
+					}
+				}
+				
+			});
+			//
+			LineSequence baseLines = getBaseRevisionLines(csetRevIndex, fileParentClogRevs);
+			pg.init(p1Lines, baseLines);
+			DiffRangeMap p1ToBase = new DiffRangeMap().fill(pg);
+			pg.init(baseLines, p2Lines);
+			DiffRangeMap baseToP2 = new DiffRangeMap().fill(pg);
+			return new MergeStrategy2(allMatches, p1ToBase, baseToP2);
+		} else {
+			pg.init(p2Lines, fileRevLines);
+			EqualBlocksCollector p2MergeCommon = new EqualBlocksCollector();
+			pg.findMatchingBlocks(p2MergeCommon);
+			return new MergeStrategy1(p2MergeCommon.matches);
+		}
+	}
+
+	private LineSequence getBaseRevisionLines(int clogRevIndex, int[] fileParentClogRevs) {
+		assert fileParentClogRevs[0] >= 0;
+		assert fileParentClogRevs[1] >= 0;
+		HgDataFile targetFile = linesCache.getFile(clogRevIndex);
+		final HgRepository repo = targetFile.getRepo();
+		if (clogMap == null) {
+			// FIXME replace HgParentChildMap with revlog.indexWalk(AncestorIterator))
+			clogMap = new HgParentChildMap<HgChangelog>(repo.getChangelog());
+			clogMap.init();
+		}
+		final HgRevisionMap<HgChangelog> m = clogMap.getRevisionMap();
+		Nodeid ancestor = clogMap.ancestor(m.revision(fileParentClogRevs[0]), m.revision(fileParentClogRevs[1]));
+		final int ancestorRevIndex = m.revisionIndex(ancestor);
+		Nodeid fr = repo.getManifest().getFileRevision(ancestorRevIndex, targetFile.getPath());
+		if (fr == null) {
+			return LineSequence.newlines(new byte[0]);
+		}
+		return linesCache.lines(ancestorRevIndex, targetFile.getRevisionIndex(fr));
+	}
+
+	private static class FileLinesCache {
+		private final LinkedList<Pair<Integer, LineSequence>> lruCache;
+		private final int limit;
+		private final LinkedList<Pair<Integer, HgDataFile>> files; // TODO in fact, need sparse array 
+
+		/**
+		 * @param lruLimit how many parsed file revisions to keep
+		 */
+		public FileLinesCache(int lruLimit) {
+			limit = lruLimit;
+			lruCache = new LinkedList<Pair<Integer, LineSequence>>();
+			files = new LinkedList<Pair<Integer,HgDataFile>>();
+		}
+		
+		public void useFileUpTo(HgDataFile df, int clogRevIndex) {
+			Pair<Integer, HgDataFile> newEntry = new Pair<Integer, HgDataFile>(clogRevIndex, df);
+			for (ListIterator<Pair<Integer, HgDataFile>> it = files.listIterator(); it.hasNext();) {
+				Pair<Integer, HgDataFile> e = it.next();
+				if (e.first() == clogRevIndex) {
+					assert e.second().getPath().equals(df.getPath());
+					return;
+				}
+				if (e.first() > clogRevIndex) {
+					// insert new entry before current
+					it.previous();
+					it.add(newEntry);
+					return;
+				}
+			}
+			files.add(newEntry);
+		}
+		
+		public HgDataFile getFile(int clogRevIndex) {
+			for (Pair<Integer, HgDataFile> e : files) {
+				if (e.first() >= clogRevIndex) {
+					return e.second();
+				}
+			}
+			throw new HgInvalidStateException(String.format("Got %d file-changelog mappings, but no luck for revision %d.", files.size(), clogRevIndex));
+		}
+
+		public LineSequence lines(int clogRevIndex, int fileRevIndex) throws HgRuntimeException {
+			Pair<Integer, LineSequence> cached = checkCache(clogRevIndex);
+			if (cached != null) {
+				return cached.second();
+			}
+			HgDataFile df = getFile(clogRevIndex);
+			try {
+				ByteArrayChannel c;
+				df.content(fileRevIndex, c = new ByteArrayChannel());
+				LineSequence rv = LineSequence.newlines(c.toArray());
+				lruCache.addFirst(new Pair<Integer, LineSequence>(clogRevIndex, rv));
+				if (lruCache.size() > limit) {
+					lruCache.removeLast();
+				}
+				return rv;
+			} catch (CancelledException ex) {
+				// TODO likely it was bad idea to throw cancelled exception from content()
+				// deprecate and provide alternative?
+				HgInvalidStateException ise = new HgInvalidStateException("ByteArrayChannel never throws CancelledException");
+				ise.initCause(ex);
+				throw ise;
+			}
+		}
+		
+		private Pair<Integer,LineSequence> checkCache(int fileRevIndex) {
+			Pair<Integer, LineSequence> rv = null;
+			for (ListIterator<Pair<Integer, LineSequence>> it = lruCache.listIterator(); it.hasNext(); ) {
+				Pair<Integer, LineSequence> p = it.next();
+				if (p.first() == fileRevIndex) {
+					rv = p;
+					it.remove();
+					break;
+				}
+			}
+			if (rv != null) {
+				lruCache.addFirst(rv);
+			}
+			return rv;
+		}
+	}
+
+	private static class BlameBlockInspector extends DiffHelper.DeltaInspector<LineSequence> {
+		private final HgBlameInspector insp;
+		private final int csetOrigin;
+		private final int csetTarget;
+		private MergeResolutionStrategy p2MergeCommon;
+		private int csetMergeParent;
+		private final AnnotateRev annotatedRevision;
+		private HgCallbackTargetException error;
+
+		public BlameBlockInspector(HgDataFile df, int fileRevIndex, HgBlameInspector inspector, int originCset, int targetCset) {
+			assert inspector != null;
+			insp = inspector;
+			annotatedRevision = new AnnotateRev();
+			annotatedRevision.set(df, fileRevIndex);
+			csetOrigin = originCset;
+			csetTarget = targetCset;
+		}
+		
+		public void setMergeParent2(MergeResolutionStrategy p2MergeStrategy, int parentCset2) {
+			p2MergeCommon = p2MergeStrategy;
+			csetMergeParent = parentCset2;
+		}
+		
+		@Override
+		public void begin(LineSequence s1, LineSequence s2) {
+			super.begin(s1, s2);
+			if (shallStop()) {
+				return;
+			}
+			ContentBlock originContent = new ContentBlock(s1);
+			ContentBlock targetContent = new ContentBlock(s2);
+			annotatedRevision.set(originContent, targetContent);
+			annotatedRevision.set(csetOrigin, csetTarget, p2MergeCommon != null ? csetMergeParent : NO_REVISION);
+			RevisionDescriptor.Recipient curious = Adaptable.Factory.getAdapter(insp, RevisionDescriptor.Recipient.class, null);
+			if (curious != null) {
+				try {
+					curious.start(annotatedRevision);
+				} catch (HgCallbackTargetException ex) {
+					error = ex;
+				}
+			}
+		}
+		
+		@Override
+		public void end() {
+			super.end();
+			if (shallStop()) {
+				return;
+			}
+			RevisionDescriptor.Recipient curious = Adaptable.Factory.getAdapter(insp, RevisionDescriptor.Recipient.class, null);
+			if (curious != null) {
+				try {
+					curious.done(annotatedRevision);
+				} catch (HgCallbackTargetException ex) {
+					error = ex;
+				}
+			}
+			p2MergeCommon = null;
+		}
+
+		@Override
+		protected void changed(int s1From, int s1To, int s2From, int s2To) {
+			if (shallStop()) {
+				return;
+			}
+			try {
+				if (p2MergeCommon != null) {
+					IntSliceSeq mergeRanges = p2MergeCommon.combineAndMarkRangesWithSource(s1From, s1To, s2From, s2To, csetOrigin, csetMergeParent);
+					
+					/*
+					 * Usecases, how it USED TO BE initially:
+					 * 3 lines changed to 10 lines. range of 10 lines breaks down to 2 from p2, 3 from p1, and 5 from p2.
+					 * We report: 2 lines changed to 2(p2), then 1 line changed with 3(p1) and 5 lines added from p2.
+					 * 
+					 * 10 lines changed to 3 lines, range of 3 lines breaks down to 2 line from p1 and 1 line from p2.
+					 * We report: 2 lines changed to 2(p1) and 8 lines changed to 1(p2)
+					 * 
+					 * NOW, lines from p2 are always reported as pure add (since we need their insertion point to be in p2, not in p1)
+					 * and we try to consume p1 changes as soon as we see first p1's range 
+					 */
+					int s1TotalLines = s1To - s1From, s1ConsumedLines = 0, s1Start = s1From;
+					
+					for (Iterator<IntTuple> it = mergeRanges.iterator(); it.hasNext();) {
+						IntTuple mergeRange = it.next();
+						final int rangeOrigin = mergeRange.at(0);
+						final int rangeStart = mergeRange.at(1);
+						final int rangeLen = mergeRange.at(2);
+						final boolean lastRange = it.hasNext();
+						final int s1LinesLeft = s1TotalLines - s1ConsumedLines;
+						// how many lines we may report as changed (don't use more than in range unless it's the very last range)
+						final int s1LinesToBorrow = lastRange ? s1LinesLeft : Math.min(s1LinesLeft, rangeLen);
+						if (rangeOrigin != csetMergeParent && s1LinesToBorrow > 0) {
+							ChangeBlockImpl block = getChangeBlock(s1Start, s1LinesToBorrow, rangeStart, rangeLen);
+							block.setOriginAndTarget(rangeOrigin, csetTarget);
+							insp.changed(block);
+							s1ConsumedLines += s1LinesToBorrow;
+							s1Start += s1LinesToBorrow;
+						} else {
+							int blockInsPoint = rangeOrigin != csetMergeParent ? s1Start : p2MergeCommon.getLineInP2(rangeStart);
+							ChangeBlockImpl block = getAddBlock(rangeStart, rangeLen, blockInsPoint);
+							block.setOriginAndTarget(rangeOrigin, csetTarget);
+							insp.added(block);
+						}
+					}
+					if (s1ConsumedLines != s1TotalLines) {
+						assert s1ConsumedLines < s1TotalLines : String.format("Expected to process %d lines, but actually was %d", s1TotalLines, s1ConsumedLines);
+						// either there were no ranges from p1, whole s2From..s2To range came from p2, shall report as deleted
+						// or the ranges found were not enough to consume whole s2From..s2To
+						// The "deletion point" is shifted to the end of last csetOrigin->csetTarget change
+						int s2DeletePoint = s2From + s1ConsumedLines;
+						ChangeBlockImpl block =  new ChangeBlockImpl(annotatedRevision.origin, null, s1Start, s1To - s1Start, -1, -1, -1, s2DeletePoint);
+						block.setOriginAndTarget(csetOrigin, csetTarget);
+						insp.deleted(block);
+					}
+				} else {
+					ChangeBlockImpl block = getChangeBlock(s1From, s1To - s1From, s2From, s2To - s2From);
+					block.setOriginAndTarget(csetOrigin, csetTarget);
+					insp.changed(block);
+				}
+			} catch (HgCallbackTargetException ex) {
+				error = ex;
+			}
+		}
+		
+		@Override
+		protected void added(int s1InsertPoint, int s2From, int s2To) {
+			if (shallStop()) {
+				return;
+			}
+			try {
+				if (p2MergeCommon != null) {
+					IntSliceSeq mergeRanges = p2MergeCommon.combineAndMarkRangesWithSource(s1InsertPoint, s2From, s2To, csetOrigin, csetMergeParent);
+					int insPoint = s1InsertPoint; // track changes to insertion point
+					for (IntTuple mergeRange : mergeRanges) {
+						int rangeOrigin = mergeRange.at(0);
+						int rangeStart = mergeRange.at(1);
+						int rangeLen = mergeRange.at(2);
+						// XXX likely need somewhat similar to the code above: 
+						// int blockInsPoint = rangeOrigin != csetMergeParent ? s1Start : p2MergeCommon.reverseMapLine(rangeStart);
+						//
+						ChangeBlockImpl block = getAddBlock(rangeStart, rangeLen, insPoint);
+						block.setOriginAndTarget(rangeOrigin, csetTarget);
+						insp.added(block);
+						// indicate insPoint moved down number of lines we just reported
+						insPoint += rangeLen;
+					}
+				} else {
+					ChangeBlockImpl block = getAddBlock(s2From, s2To - s2From, s1InsertPoint);
+					block.setOriginAndTarget(csetOrigin, csetTarget);
+					insp.added(block);
+				}
+			} catch (HgCallbackTargetException ex) {
+				error = ex;
+			}
+		}
+		
+		@Override
+		protected void deleted(int s2DeletePoint, int s1From, int s1To) {
+			if (shallStop()) {
+				return;
+			}
+			try {
+				ChangeBlockImpl block = new ChangeBlockImpl(annotatedRevision.origin, null, s1From, s1To - s1From, -1, -1, -1, s2DeletePoint);
+				block.setOriginAndTarget(csetOrigin, csetTarget);
+				insp.deleted(block);
+			} catch (HgCallbackTargetException ex) {
+				error = ex;
+			}
+		}
+
+		@Override
+		protected void unchanged(int s1From, int s2From, int length) {
+			if (shallStop()) {
+				return;
+			}
+			try {
+				EqualBlockImpl block = new EqualBlockImpl(s1From, s2From, length, annotatedRevision.target);
+				block.setOriginAndTarget(csetOrigin, csetTarget);
+				insp.same(block);
+			} catch (HgCallbackTargetException ex) {
+				error = ex;
+			}
+		}
+		
+		void checkErrors() throws HgCallbackTargetException {
+			if (error != null) {
+				throw error;
+			}
+		}
+		
+		private boolean shallStop() {
+			return error != null;
+		}
+		
+		private ChangeBlockImpl getAddBlock(int start, int len, int insPoint) {
+			return new ChangeBlockImpl(null, annotatedRevision.target, -1, -1, start, len, insPoint, -1);
+		}
+		
+		private ChangeBlockImpl getChangeBlock(int start1, int len1, int start2, int len2) {
+			return new ChangeBlockImpl(annotatedRevision.origin, annotatedRevision.target, start1, len1, start2, len2, start1, start2);
+		}
+	}
+	
+	private static class BlockImpl implements Block {
+		private int originCset;
+		private int targetCset;
+
+		void setOriginAndTarget(int originChangesetIndex, int targetChangesetIndex) {
+			// XXX perhaps, shall be part of Inspector API, rather than Block's
+			// as they don't change between blocks (although the moment about merged revisions)
+			// is not yet clear to me
+			originCset = originChangesetIndex;
+			targetCset = targetChangesetIndex;
+		}
+
+		public int originChangesetIndex() {
+			return originCset;
+		}
+
+		public int targetChangesetIndex() {
+			return targetCset;
+		}
+	}
+
+	private static class EqualBlockImpl extends BlockImpl implements EqualBlock {
+		private final int start1, start2;
+		private final int length;
+		private final ContentBlock fullContent;
+		private FilterBlock myContent;
+		
+		EqualBlockImpl(int blockStartSeq1, int blockStartSeq2, int blockLength, ContentBlock targetContent) {
+			start1 = blockStartSeq1;
+			start2 = blockStartSeq2;
+			length = blockLength;
+			fullContent = targetContent;
+		}
+
+		public int originStart() {
+			return start1;
+		}
+
+		public int targetStart() {
+			return start2;
+		}
+
+		public int length() {
+			return length;
+		}
+		
+		public BlockData content() {
+			if (myContent == null) {
+				myContent = new FilterBlock(fullContent, start2, length);
+			}
+			return myContent;
+		}
+		
+		@Override
+		public String toString() {
+			return String.format("@@ [%d..%d) == [%d..%d) @@", start1, start1+length, start2, start2+length);
+		}
+	}
+	
+	private static class ChangeBlockImpl extends BlockImpl implements ChangeBlock {
+		private final ContentBlock oldContent;
+		private final ContentBlock newContent;
+		private final int s1Start;
+		private final int s1Len;
+		private final int s2Start;
+		private final int s2Len;
+		private final int s1InsertPoint;
+		private final int s2DeletePoint;
+		private FilterBlock addedBlock, removedBlock;
+
+		public ChangeBlockImpl(ContentBlock c1, ContentBlock c2, int s1Start, int s1Len, int s2Start, int s2Len, int s1InsertPoint, int s2DeletePoint) {
+			oldContent = c1;
+			newContent = c2;
+			this.s1Start = s1Start;
+			this.s1Len = s1Len;
+			this.s2Start = s2Start;
+			this.s2Len = s2Len;
+			this.s1InsertPoint = s1InsertPoint;
+			this.s2DeletePoint = s2DeletePoint;
+		}
+		
+		public int insertedAt() {
+			return s1InsertPoint;
+		}
+
+		public int firstAddedLine() {
+			return s2Start;
+		}
+
+		public int totalAddedLines() {
+			return s2Len;
+		}
+
+		public BlockData addedLines() {
+			if (addedBlock == null) {
+				addedBlock = new FilterBlock(newContent, firstAddedLine(), totalAddedLines());
+			}
+			return addedBlock;
+		}
+		
+		public int removedAt() {
+			return s2DeletePoint;
+		}
+
+		public int firstRemovedLine() {
+			return s1Start;
+		}
+
+		public int totalRemovedLines() {
+			return s1Len;
+		}
+
+		public BlockData removedLines() {
+			if (removedBlock == null) {
+				removedBlock = new FilterBlock(oldContent, firstRemovedLine(), totalRemovedLines());
+			}
+			return removedBlock;
+		}
+		
+		@Override
+		public String toString() {
+			if (s2DeletePoint == -1) {
+				return String.format("@@ -%d,0 +%d,%d @@", insertedAt(), firstAddedLine(), totalAddedLines());
+			} else if (s1InsertPoint == -1) {
+				// delete only
+				return String.format("@@ -%d,%d +%d,0 @@", firstRemovedLine(), totalRemovedLines(), removedAt());
+			}
+			return String.format("@@ -%d,%d +%d,%d @@", firstRemovedLine(), totalRemovedLines(), firstAddedLine(), totalAddedLines());
+		}
+	}
+	
+	private static class SingleLine implements BlockData {
+		private final ByteChain line;
+
+		public SingleLine(ByteChain lineContent) {
+			line = lineContent;
+		}
+
+		public BlockData elementAt(int index) {
+			assert false;
+			return null;
+		}
+
+		public int elementCount() {
+			return 0;
+		}
+
+		public byte[] asArray() {
+			return line.data();
+		}
+	}
+	
+	private static class ContentBlock implements BlockData {
+		private final LineSequence seq;
+
+		public ContentBlock(LineSequence sequence) {
+			seq = sequence;
+		}
+
+		public BlockData elementAt(int index) {
+			return new SingleLine(seq.chunk(index));
+		}
+
+		public int elementCount() {
+			return seq.chunkCount() - 1;
+		}
+
+		public byte[] asArray() {
+			return seq.data(0, seq.chunkCount() - 1);
+		}
+	}
+	
+	private static class FilterBlock implements BlockData {
+		private final ContentBlock contentBlock;
+		private final int from;
+		private final int length;
+
+		public FilterBlock(ContentBlock bd, int startFrom, int len) {
+			assert bd != null;
+			assert startFrom + len < bd.seq.chunkCount(); // there's one extra chunk in the end, so strict less is ok
+			contentBlock = bd;
+			from = startFrom;
+			length = len;
+		}
+
+		public BlockData elementAt(int index) {
+			if (index < 0 || index >= length) {
+				throw new IllegalArgumentException(String.format("Expected value from [0..%d), got %d", length, index));
+			}
+			return contentBlock.elementAt(from + index);
+		}
+
+		public int elementCount() {
+			return length;
+		}
+
+		public byte[] asArray() {
+			return contentBlock.seq.data(from, from + length);
+		}
+	}
+
+	private static class EqualBlocksCollector implements DiffHelper.MatchInspector<LineSequence> {
+		private final RangePairSeq matches = new RangePairSeq();
+
+		public void begin(LineSequence s1, LineSequence s2) {
+		}
+
+		public void match(int startSeq1, int startSeq2, int matchLength) {
+			matches.add(startSeq1, startSeq2, matchLength);
+		}
+
+		public void end() {
+		}
+
+		public void intersectWithTarget(int start, int length, IntVector result) {
+			int s = start;
+			for (int l = start, x = start + length; l < x; l++) {
+				if (!matches.includesTargetLine(l)) {
+					if (l - s > 0) {
+						result.add(s);
+						result.add(l - s);
+					}
+					s = l+1;
+				}
+			}
+			if (s < start+length) {
+				result.add(s);
+				result.add((start + length) - s);
+			}
+		}
+		
+	}
+
+	interface MergeResolutionStrategy {
+		/**
+		 * breaks region [start2..end2) into ranges according to deduced (or simply guessed)
+		 * matching of [start1..end1) lines to lines in source1 and source2
+		 * @return list of tuples (source, start, length), where source is one of the identifiers supplied
+		 */
+		public IntSliceSeq combineAndMarkRangesWithSource(int start1, int end1, int start2, int end2, int source1, int source2);
+		public IntSliceSeq combineAndMarkRangesWithSource(int insPoint, int start, int end, int source1, int source2);
+		public int getLineInP2(int mergeLine);
+	}
+
+	// report lines as merged from p2 solely based on whether target line belongs
+	// to a region that is equal to p2 region
+	private static class MergeStrategy1 implements MergeResolutionStrategy {
+		// equal ranges in p2 and merged revision
+		private final RangePairSeq matches; 
+		private final IntSliceSeq mergeRanges;
+
+		public MergeStrategy1(RangePairSeq p2EqualToM) {
+			matches = p2EqualToM;
+			mergeRanges = new IntSliceSeq(3, 10, 10);
+		}
+
+		/*
+		 * intersects [start..start+length) with ranges of target lines, and based on the intersection 
+		 * breaks initial range into smaller ranges and records them into result, with marker to indicate
+		 * whether the range is from initial range (markerSource) or is a result of the intersection with target
+		 * (markerTarget)
+		 */
+		private IntSliceSeq doCombine(int start, int length, int markerSource, int markerTarget) {
+			mergeRanges.clear();
+			assert mergeRanges.sliceSize() == 3;
+			int sourceStart = start, targetStart = start, sourceEnd = start + length;
+			for (int l = sourceStart; l < sourceEnd; l++) {
+				if (matches.includesTargetLine(l)) {
+					// l is from target
+					if (sourceStart < l) {
+						// few lines from source range were not in the target, report them
+						mergeRanges.add(markerSource, sourceStart, l - sourceStart);
+					}
+					// indicate the earliest line from source range to use
+					sourceStart = l + 1;
+				} else {
+					// l is not in target
+					if (targetStart < l) {
+						// report lines from target range
+						mergeRanges.add(markerTarget, targetStart, l - targetStart);
+					}
+					// next line *may* be from target
+					targetStart = l + 1;
+				}
+			}
+			// if source range end with line from target, sourceStart would be == sourceEnd, and we need to add range with markerTarget
+			// if source range doesn't end with target line, targetStart == sourceEnd, while sourceStart < sourceEnd
+			if (sourceStart < sourceEnd) {
+				assert targetStart == sourceEnd;
+				// something left from the source range
+				mergeRanges.add(markerSource, sourceStart, sourceEnd - sourceStart);
+			} else if (targetStart < sourceEnd) {
+				assert sourceStart == sourceEnd;
+				mergeRanges.add(markerTarget, targetStart, sourceEnd - targetStart);
+			}
+			return mergeRanges;
+		}
+
+		public int getLineInP2(int mergeLine) {
+			return matches.reverseMapLine(mergeLine);
+		}
+
+		public IntSliceSeq combineAndMarkRangesWithSource(int start1, int end1, int start2, int end2, int source1, int source2) {
+			return doCombine(start2, end2 - start2, source1, source2);
+		}
+
+		public IntSliceSeq combineAndMarkRangesWithSource(int insPoint, int start, int end, int source1, int source2) {
+			return doCombine(start, end - start, source1, source2);
+		}
+	}
+	
+	private static class MergeStrategy2 implements MergeResolutionStrategy {
+		// equal ranges in p2 and merged revision
+		private final List<RangePairSeq> matches; 
+		private final IntSliceSeq mergeRanges;
+		private final DiffRangeMap p1ToBase;
+		private final DiffRangeMap baseToP2;
+
+		public MergeStrategy2(List<RangePairSeq> p2EqualToM, DiffRangeMap p1ToBaseRanges, DiffRangeMap baseToP2Ranges) {
+			matches = p2EqualToM;
+			p1ToBase = p1ToBaseRanges;
+			baseToP2= baseToP2Ranges;
+			mergeRanges = new IntSliceSeq(3, 10, 10);
+		}
+
+
+		public IntSliceSeq combineAndMarkRangesWithSource(int insPoint, int start, int end, int source1, int source2) {
+			return combineAndMarkRangesWithSource(insPoint, insPoint, start, end, source1, source2);
+		}
+
+		public IntSliceSeq combineAndMarkRangesWithSource(int start1, int end1, int start2, int end2, int source1, int source2) {
+			mergeRanges.clear();
+			IntSliceSeq mergedLines = new IntSliceSeq(2, end2-start2, 0);
+			for (int i = start2; i < end2; i++) {
+				mergedLines.add(source1, 0);
+			}
+			// [s1Start..s1End) // range in p1 seen as changed in m
+			for (RangePair p1_b : p1ToBase.findInSource(start1, end1)) {
+				// there might be few ranges in (p1-base) that overlap with (p1-m) changes
+				for (RangePair b_p2 : baseToP2.findInSource(p1_b.start2(), p1_b.end2())) {
+					// regions in p2 that correspond to affected regions in base
+					for (int p2Line = b_p2.start2(); p2Line < b_p2.end2(); p2Line++) {
+						for (RangePairSeq eq : matches) {
+							if (eq.includesOriginLine(p2Line)) {
+								// this line in p2 is equal to some line in merge
+								int mergeLine = eq.mapLineIndex(p2Line);
+								if (mergeLine >= start2 && mergeLine < end2) {
+									mergedLines.set(mergeLine - start2, source2, p2Line);
+								}
+							}
+						}
+					}
+				}
+			}
+			int lineCount = 0, start = start2;
+			int lastSeenSource = source1;
+			for (IntTuple t : mergedLines) {
+				if (t.at(0) == lastSeenSource) {
+					lineCount++;
+				} else {
+					if (lineCount > 0) {
+						mergeRanges.add(lastSeenSource, start, lineCount);
+						start += lineCount;
+					}
+					lineCount = 1;
+					lastSeenSource = t.at(0);
+				}
+			}
+			if (lineCount > 0) {
+				mergeRanges.add(lastSeenSource, start, lineCount);
+			}
+			return mergeRanges;
+		}
+
+		public int getLineInP2(int mergeLine) {
+			for (RangePairSeq eq : matches) {
+				if (eq.includesTargetLine(mergeLine)) {
+					return eq.reverseMapLine(mergeLine);
+				}
+			}
+			return -1;
+		}
+	}
+
+
+	private static class AnnotateRev implements RevisionDescriptor {
+		public ContentBlock origin, target;
+		public int originCset, targetCset, mergeCset, fileRevIndex;
+		public HgDataFile df;
+		
+		public void set(HgDataFile file, int fileRev) {
+			df = file;
+			fileRevIndex = fileRev;
+		}
+		public void set(ContentBlock o, ContentBlock t) {
+			origin = o;
+			target = t;
+		}
+		public void set(int o, int t, int m) {
+			originCset = o;
+			targetCset = t;
+			mergeCset = m;
+		}
+		
+		public BlockData origin() {
+			return origin;
+		}
+
+		public BlockData target() {
+			return target;
+		}
+
+		public int originChangesetIndex() {
+			return originCset;
+		}
+
+		public int targetChangesetIndex() {
+			return targetCset;
+		}
+
+		public boolean isMerge() {
+			return mergeCset != NO_REVISION;
+		}
+
+		public int mergeChangesetIndex() {
+			return mergeCset;
+		}
+
+		public int fileRevisionIndex() {
+			return fileRevIndex;
+		}
+		public HgDataFile file() {
+			return df;
+		}
+		@Override
+		public String toString() {
+			if (isMerge()) {
+				return String.format("[%d,%d->%d]", originCset, mergeCset, targetCset);
+			}
+			return String.format("[%d->%d]", originCset, targetCset);
+		}
+	}
+
+	public static void main(String[] args) {
+		EqualBlocksCollector bc = new EqualBlocksCollector();
+		bc.match(-1, 5, 3);
+		bc.match(-1, 10, 2);
+		bc.match(-1, 15, 3);
+		bc.match(-1, 20, 3);
+		IntVector r = new IntVector();
+		bc.intersectWithTarget(7, 10, r);
+		for (int i = 0; i < r.size(); i+=2) {
+			System.out.printf("[%d..%d) ", r.get(i), r.get(i) + r.get(i+1));
+		}
+		System.out.println();
+		MergeStrategy1 ms = new MergeStrategy1(bc.matches);
+		IntSliceSeq mr = ms.doCombine(0, 16, 508, 514);
+		for (IntTuple t : mr) {
+			System.out.printf("%d:[%d..%d)  ", t.at(0), t.at(1), t.at(1) + t.at(2));
+		}
+		System.out.println();
+		System.out.println();
+		DiffRangeMap m1 = new DiffRangeMap(); // p1 -> base
+		m1.match(0, 0, 1); // =1..1 -> 1..1
+		m1.match(7, 3, 0);  // *2..7 -> 2..3
+		DiffRangeMap m2 = new DiffRangeMap(); // base -> p2
+		m2.match(0, 0, 1); // =1..1 -> 1..1
+		m2.match(3, 3, 0); // *2..3 -> 2..3
+		RangePairSeq eq1 = new RangePairSeq();
+		eq1.add(0, 0, 3);
+		RangePairSeq eq2 = new RangePairSeq();
+		eq2.add(0, 4, 3);
+		MergeStrategy2 ms2 = new MergeStrategy2(Arrays.asList(eq1, eq2), m1, m2);
+		mr = ms2.combineAndMarkRangesWithSource(5, 7, 5, 7, 33, 44);
+		for (IntTuple t : mr) {
+			System.out.printf("%d:[%d..%d)  ", t.at(0), t.at(1), t.at(1) + t.at(2));
+		}
+	}
+}