--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/diff/ReverseAnnotateInspector.java	Wed Aug 14 14:51:51 2013 +0200
@@ -0,0 +1,168 @@
+/*
+ * 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.repo.HgRepository.NO_REVISION;
+
+import java.util.Arrays;
+
+import org.tmatesoft.hg.core.HgAnnotateCommand;
+import org.tmatesoft.hg.core.HgBlameInspector;
+import org.tmatesoft.hg.core.HgIterateDirection;
+import org.tmatesoft.hg.core.HgBlameInspector.RevisionDescriptor;
+import org.tmatesoft.hg.core.HgCallbackTargetException;
+import org.tmatesoft.hg.internal.IntMap;
+import org.tmatesoft.hg.repo.HgInvalidStateException;
+import org.tmatesoft.hg.util.CancelSupport;
+import org.tmatesoft.hg.util.CancelledException;
+import org.tmatesoft.hg.util.ProgressSupport;
+
+/**
+ * Produce output like 'hg annotate' does.
+ * Expects revisions to come in order from child to parent.
+ * Unlike {@link ForwardAnnotateInspector}, can be easily modified to report lines as soon as its origin is detected.
+ * 
+ * (+) Handles annotate of partial history, at any moment lines with ({@link #knownLines} == <code>false</code> indicate lines
+ * that were added prior to any revision already visited. 
+ * 
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public class ReverseAnnotateInspector implements HgBlameInspector, RevisionDescriptor.Recipient {
+
+	// keeps <startSeq1, startSeq2, len> of equal blocks, origin to target, from some previous step
+	private RangePairSeq activeEquals;
+	// equal blocks of the current iteration, to be recalculated before next step
+	// to track line number (current target to ultimate target) mapping 
+	private RangePairSeq intermediateEquals = new RangePairSeq();
+
+	private boolean[] knownLines;
+	private RevisionDescriptor revisionDescriptor;
+	private BlockData lineContent;
+
+	private IntMap<RangePairSeq> mergedRanges = new IntMap<RangePairSeq>(10);
+	private IntMap<RangePairSeq> equalRanges = new IntMap<RangePairSeq>(10);
+	private boolean activeEqualsComesFromMerge = false;
+
+	private int[] lineRevisions;
+	private int[] lineNumbers;
+
+	/**
+	 * @return desired order of iteration for diff
+	 */
+	public HgIterateDirection iterateDirection() {
+		return HgIterateDirection.NewToOld;
+	}
+
+	public void report(int annotateRevIndex, HgAnnotateCommand.Inspector insp, ProgressSupport progress, CancelSupport cancel) throws HgCallbackTargetException, CancelledException {
+		LineImpl li = new LineImpl();
+		progress.start(lineRevisions.length);
+		for (int i = 0; i < lineRevisions.length; i++) {
+			byte[] c = lineContent.elementAt(i).asArray();
+			li.init(i+1, lineNumbers[i] + 1, lineRevisions[i], c);
+			insp.next(li);
+			progress.worked(1);
+			cancel.checkCancelled();
+		}
+		progress.done();
+	}
+
+	public void start(RevisionDescriptor rd) {
+		revisionDescriptor = rd;
+		if (knownLines == null) {
+			lineContent = rd.target();
+			knownLines = new boolean[lineContent.elementCount()];
+			lineRevisions = new int [knownLines.length];
+			Arrays.fill(lineRevisions, NO_REVISION);
+			lineNumbers = new int[knownLines.length];
+			activeEquals = new RangePairSeq();
+			activeEquals.add(0, 0, knownLines.length);
+			equalRanges.put(rd.targetChangesetIndex(), activeEquals);
+		} else {
+			activeEquals = equalRanges.get(rd.targetChangesetIndex());
+			if (activeEquals == null) {
+				// we didn't see this target revision as origin yet
+				// the only way this may happen is that this revision was a merge parent
+				activeEquals = mergedRanges.get(rd.targetChangesetIndex());
+				activeEqualsComesFromMerge = true;
+				if (activeEquals == null) {
+					throw new HgInvalidStateException(String.format("Can't find previously visited revision %d (while in %d->%1$d diff)", rd.targetChangesetIndex(), rd.originChangesetIndex()));
+				}
+			}
+		}
+	}
+
+	public void done(RevisionDescriptor rd) {
+		// update line numbers of the intermediate target to point to ultimate target's line numbers
+		RangePairSeq v = intermediateEquals.intersect(activeEquals);
+		if (activeEqualsComesFromMerge) {
+			mergedRanges.put(rd.originChangesetIndex(), v);
+		} else {
+			equalRanges.put(rd.originChangesetIndex(), v);
+		}
+		if (rd.isMerge() && !mergedRanges.containsKey(rd.mergeChangesetIndex())) {
+			// seen merge, but no lines were merged from p2.
+			// Add empty range to avoid uncertainty when a parent of p2 pops in
+			mergedRanges.put(rd.mergeChangesetIndex(), new RangePairSeq());
+		}
+		intermediateEquals.clear();
+		activeEquals = null;
+		activeEqualsComesFromMerge = false;
+		revisionDescriptor = null;
+	}
+
+	public void same(EqualBlock block) {
+		intermediateEquals.add(block.originStart(), block.targetStart(), block.length());
+	}
+
+	public void added(AddBlock block) {
+		RangePairSeq rs = null;
+		if (revisionDescriptor.isMerge() && block.originChangesetIndex() == revisionDescriptor.mergeChangesetIndex()) {
+			rs = mergedRanges.get(revisionDescriptor.mergeChangesetIndex());
+			if (rs == null) {
+				mergedRanges.put(revisionDescriptor.mergeChangesetIndex(), rs = new RangePairSeq());
+			}
+		}
+		if (activeEquals.size() == 0) {
+			return;
+		}
+		for (int i = 0, ln = block.firstAddedLine(), x = block.totalAddedLines(); i < x; i++, ln++) {
+			int lnInFinal = activeEquals.mapLineIndex(ln);
+			if (lnInFinal != -1/* && !knownLines[lnInFinal]*/) {
+				if (rs != null) {
+					rs.add(block.insertedAt() + i, lnInFinal, 1);
+				} else {
+					line(lnInFinal, ln, block.targetChangesetIndex());
+				}
+				knownLines[lnInFinal] = true;
+			}
+		}
+	}
+
+	public void changed(ChangeBlock block) {
+		added(block);
+	}
+
+	public void deleted(DeleteBlock block) {
+	}
+
+	private void line(int lineNumber, int firstAppearance, int changesetRevIndex) {
+		lineRevisions[lineNumber] = changesetRevIndex;
+		lineNumbers[lineNumber] = firstAppearance;
+	}
+}
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