--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/core/HgMergeCommand.java	Wed Aug 14 20:07:26 2013 +0200
@@ -0,0 +1,205 @@
+/*
+ * 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.core;
+
+import static org.tmatesoft.hg.repo.HgRepository.BAD_REVISION;
+
+import java.io.InputStream;
+
+import org.tmatesoft.hg.internal.Callback;
+import org.tmatesoft.hg.internal.CsetParamKeeper;
+import org.tmatesoft.hg.internal.Experimental;
+import org.tmatesoft.hg.internal.ManifestRevision;
+import org.tmatesoft.hg.internal.Pool;
+import org.tmatesoft.hg.repo.HgChangelog;
+import org.tmatesoft.hg.repo.HgParentChildMap;
+import org.tmatesoft.hg.repo.HgRepository;
+import org.tmatesoft.hg.repo.HgRepositoryLock;
+import org.tmatesoft.hg.repo.HgRevisionMap;
+import org.tmatesoft.hg.repo.HgRuntimeException;
+import org.tmatesoft.hg.util.CancelledException;
+import org.tmatesoft.hg.util.Path;
+
+/**
+ * Merge two revisions, 'hg merge REV' counterpart
+ * 
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ * @since 1.2
+ */
+@Experimental(reason="Provisional API. Work in progress")
+public class HgMergeCommand extends HgAbstractCommand<HgMergeCommand> {
+
+	private final HgRepository repo;
+	private int firstCset, secondCset, ancestorCset;
+
+	public HgMergeCommand(HgRepository hgRepo) {
+		repo = hgRepo;
+		firstCset = secondCset = ancestorCset = BAD_REVISION;
+	}
+	
+	public HgMergeCommand changeset(Nodeid changeset) throws HgBadArgumentException {
+		initHeadsAndAncestor(new CsetParamKeeper(repo).set(changeset).get());
+		return this;
+	}
+	
+	public HgMergeCommand changeset(int revisionIndex) throws HgBadArgumentException {
+		initHeadsAndAncestor(new CsetParamKeeper(repo).set(revisionIndex).get());
+		return this;
+	}
+
+	public void execute(Mediator mediator) throws HgCallbackTargetException, HgRepositoryLockException, HgLibraryFailureException, CancelledException {
+		if (firstCset == BAD_REVISION || secondCset == BAD_REVISION || ancestorCset == BAD_REVISION) {
+			throw new IllegalArgumentException("Merge heads and their ancestors are not initialized");
+		}
+		final HgRepositoryLock wdLock = repo.getWorkingDirLock();
+		wdLock.acquire();
+		try {
+			Pool<Nodeid> cacheRevs = new Pool<Nodeid>();
+			Pool<Path> cacheFiles = new Pool<Path>();
+			ManifestRevision m1, m2, ma;
+			m1 = new ManifestRevision(cacheRevs, cacheFiles).init(repo, firstCset);
+			m2 = new ManifestRevision(cacheRevs, cacheFiles).init(repo, secondCset);
+			ma = new ManifestRevision(cacheRevs, cacheFiles).init(repo, ancestorCset);
+			ResolverImpl resolver = new ResolverImpl();
+			for (Path f : m1.files()) {
+				Nodeid fileRevBase, fileRevA, fileRevB;
+				if (m2.contains(f)) {
+					fileRevA = m1.nodeid(f);
+					fileRevB = m2.nodeid(f);
+					fileRevBase = ma.contains(f) ? ma.nodeid(f) : null;
+					if (fileRevA.equals(fileRevB)) {
+						HgFileRevision fr = new HgFileRevision(repo, fileRevA, m1.flags(f), f);
+						mediator.same(fr, fr, resolver);
+					} else if (fileRevBase == fileRevA) {
+						assert fileRevBase != null;
+						HgFileRevision frBase = new HgFileRevision(repo, fileRevBase, ma.flags(f), f);
+						HgFileRevision frSecond= new HgFileRevision(repo, fileRevB, m2.flags(f), f);
+						mediator.fastForwardB(frBase, frSecond, resolver);
+					} else if (fileRevBase == fileRevB) {
+						assert fileRevBase != null;
+						HgFileRevision frBase = new HgFileRevision(repo, fileRevBase, ma.flags(f), f);
+						HgFileRevision frFirst = new HgFileRevision(repo, fileRevA, m1.flags(f), f);
+						mediator.fastForwardA(frBase, frFirst, resolver);
+					} else {
+						HgFileRevision frBase = fileRevBase == null ? null : new HgFileRevision(repo, fileRevBase, ma.flags(f), f);
+						HgFileRevision frFirst = new HgFileRevision(repo, fileRevA, m1.flags(f), f);
+						HgFileRevision frSecond= new HgFileRevision(repo, fileRevB, m2.flags(f), f);
+						mediator.resolve(frBase, frFirst, frSecond, resolver);
+					}
+				} else {
+					// m2 doesn't contain the file, either new in m1, or deleted in m2
+					HgFileRevision frFirst = new HgFileRevision(repo, m1.nodeid(f), m1.flags(f), f);
+					if (ma.contains(f)) {
+						// deleted in m2
+						HgFileRevision frBase = new HgFileRevision(repo, ma.nodeid(f), ma.flags(f), f);
+						mediator.onlyA(frBase, frFirst, resolver);
+					} else {
+						// new in m1
+						mediator.newInA(frFirst, resolver);
+					}
+				}
+				resolver.apply();
+			} // for m1 files
+			for (Path f : m2.files()) {
+				if (m1.contains(f)) {
+					continue;
+				}
+				HgFileRevision frSecond= new HgFileRevision(repo, m2.nodeid(f), m2.flags(f), f);
+				// file in m2 is either new or deleted in m1
+				if (ma.contains(f)) {
+					// deleted in m1
+					HgFileRevision frBase = new HgFileRevision(repo, ma.nodeid(f), ma.flags(f), f);
+					mediator.onlyB(frBase, frSecond, resolver);
+				} else {
+					// new in m2
+					mediator.newInB(frSecond, resolver);
+				}
+				resolver.apply();
+			}
+		} catch (HgRuntimeException ex) {
+			throw new HgLibraryFailureException(ex);
+		} finally {
+			wdLock.release();
+		}
+	}
+
+	private void initHeadsAndAncestor(int csetIndexB) throws HgBadArgumentException {
+		firstCset = secondCset = ancestorCset = BAD_REVISION;
+		if (csetIndexB == HgRepository.BAD_REVISION) {
+			throw new HgBadArgumentException("Need valid second head for merge", null);
+		}
+		// TODO cache/share parent-child map, e.g. right in HgChangelog?! #getOrCreate
+		HgParentChildMap<HgChangelog> pmap = new HgParentChildMap<HgChangelog>(repo.getChangelog());
+		pmap.init();
+		final HgRevisionMap<HgChangelog> rmap = pmap.getRevisionMap();
+		final Nodeid csetA = repo.getWorkingCopyParents().first();
+		final Nodeid csetB = rmap.revision(csetIndexB);
+		final Nodeid ancestor = pmap.ancestor(csetA, csetB);
+		assert !ancestor.isNull();
+		if (ancestor.equals(csetA) || ancestor.equals(csetB)) {
+			throw new HgBadArgumentException(String.format("Revisions %s and %s are on the same line of descent, use update instead of merge", csetA.shortNotation(), csetB.shortNotation()), null);
+		}
+		firstCset = rmap.revisionIndex(csetA);
+		secondCset = csetIndexB;
+		ancestorCset = rmap.revisionIndex(ancestor);
+	}
+
+	/**
+	 * This is the way client code takes part in the merge process
+	 */
+	@Experimental(reason="Provisional API. Work in progress")
+	@Callback
+	public interface Mediator {
+		public void same(HgFileRevision first, HgFileRevision second, Resolver resolver) throws HgCallbackTargetException;
+		public void onlyA(HgFileRevision base, HgFileRevision rev, Resolver resolver) throws HgCallbackTargetException;
+		public void onlyB(HgFileRevision base, HgFileRevision rev, Resolver resolver) throws HgCallbackTargetException;
+		public void newInA(HgFileRevision rev, Resolver resolver) throws HgCallbackTargetException;
+		public void newInB(HgFileRevision rev, Resolver resolver) throws HgCallbackTargetException;
+		public void fastForwardA(HgFileRevision base, HgFileRevision first, Resolver resolver) throws HgCallbackTargetException;
+		public void fastForwardB(HgFileRevision base, HgFileRevision second, Resolver resolver) throws HgCallbackTargetException;
+		public void resolve(HgFileRevision base, HgFileRevision first, HgFileRevision second, Resolver resolver) throws HgCallbackTargetException;
+	}
+
+	/**
+	 * Clients shall not implement this interface.
+	 * They use this API from inside {@link Mediator#resolve(HgFileRevision, HgFileRevision, HgFileRevision, Resolver)}
+	 */
+	@Experimental(reason="Provisional API. Work in progress")
+	public interface Resolver {
+		public void use(HgFileRevision rev);
+		public void use(InputStream content);
+		public void unresolved(); // record the file for later processing by 'hg resolve'
+	}
+
+	private static class ResolverImpl implements Resolver {
+		void apply() {
+		}
+
+		public void use(HgFileRevision rev) {
+			// TODO Auto-generated method stub
+		}
+
+		public void use(InputStream content) {
+			// TODO Auto-generated method stub
+		}
+
+		public void unresolved() {
+			// TODO Auto-generated method stub
+		}
+	}
+}