--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/repo/Revlog.java	Mon Jan 24 03:14:45 2011 +0100
@@ -0,0 +1,262 @@
+/*
+ * Copyright (c) 2010-2011 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@svnkit.com
+ */
+package org.tmatesoft.hg.repo;
+
+import static org.tmatesoft.hg.repo.HgRepository.TIP;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Set;
+
+import org.tmatesoft.hg.core.Nodeid;
+
+
+/**
+ *
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+abstract class Revlog {
+
+	private final HgRepository hgRepo;
+	protected final RevlogStream content;
+
+	protected Revlog(HgRepository hgRepo, RevlogStream content) {
+		if (hgRepo == null) {
+			throw new IllegalArgumentException();
+		}
+		if (content == null) {
+			throw new IllegalArgumentException();
+		}
+		this.hgRepo = hgRepo;
+		this.content = content;
+	}
+
+	public final HgRepository getRepo() {
+		return hgRepo;
+	}
+
+	public int getRevisionCount() {
+		return content.revisionCount();
+	}
+
+	public int getLocalRevisionNumber(Nodeid nid) {
+		int revision = content.findLocalRevisionNumber(nid);
+		if (revision == Integer.MIN_VALUE) {
+			throw new IllegalArgumentException(String.format("%s doesn't represent a revision of %s", nid.toString(), this /*XXX HgDataFile.getPath might be more suitable here*/));
+		}
+		return revision;
+	}
+
+	// Till now, i follow approach that NULL nodeid is never part of revlog
+	public boolean isKnown(Nodeid nodeid) {
+		final int rn = content.findLocalRevisionNumber(nodeid);
+		if (Integer.MIN_VALUE == rn) {
+			return false;
+		}
+		if (rn < 0 || rn >= content.revisionCount()) {
+			// Sanity check
+			throw new IllegalStateException();
+		}
+		return true;
+	}
+
+	/**
+	 * Access to revision data as is (decompressed, but otherwise unprocessed, i.e. not parsed for e.g. changeset or manifest entries) 
+	 * @param nodeid
+	 */
+	public byte[] content(Nodeid nodeid) {
+		return content(getLocalRevisionNumber(nodeid));
+	}
+	
+	/**
+	 * @param revision - repo-local index of this file change (not a changelog revision number!)
+	 */
+	public byte[] content(int revision) {
+		final byte[][] dataPtr = new byte[1][];
+		Revlog.Inspector insp = new Revlog.Inspector() {
+			public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
+				dataPtr[0] = data;
+			}
+		};
+		content.iterate(revision, revision, true, insp);
+		return dataPtr[0];
+	}
+
+	/**
+	 * XXX perhaps, return value Nodeid[2] and boolean needNodeids is better (and higher level) API for this query?
+	 * 
+	 * @param revision - revision to query parents, or {@link HgRepository#TIP}
+	 * @param parentRevisions - int[2] to get local revision numbers of parents (e.g. {6, -1})
+	 * @param parent1 - byte[20] or null, if parent's nodeid is not needed
+	 * @param parent2 - byte[20] or null, if second parent's nodeid is not needed
+	 * @return
+	 */
+	public void parents(int revision, int[] parentRevisions, byte[] parent1, byte[] parent2) {
+		if (revision != TIP && !(revision >= 0 && revision < content.revisionCount())) {
+			throw new IllegalArgumentException(String.valueOf(revision));
+		}
+		if (parentRevisions == null || parentRevisions.length < 2) {
+			throw new IllegalArgumentException(String.valueOf(parentRevisions));
+		}
+		if (parent1 != null && parent1.length < 20) {
+			throw new IllegalArgumentException(parent1.toString());
+		}
+		if (parent2 != null && parent2.length < 20) {
+			throw new IllegalArgumentException(parent2.toString());
+		}
+		class ParentCollector implements Revlog.Inspector {
+			public int p1 = -1;
+			public int p2 = -1;
+			public byte[] nodeid;
+			
+			public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
+				p1 = parent1Revision;
+				p2 = parent2Revision;
+				this.nodeid = new byte[20];
+				// nodeid arg now comes in 32 byte from (as in file format description), however upper 12 bytes are zeros.
+				System.arraycopy(nodeid, nodeid.length > 20 ? nodeid.length - 20 : 0, this.nodeid, 0, 20);
+			}
+		};
+		ParentCollector pc = new ParentCollector();
+		content.iterate(revision, revision, false, pc);
+		parentRevisions[0] = pc.p1;
+		parentRevisions[1] = pc.p2;
+		if (parent1 != null) {
+			if (parentRevisions[0] == -1) {
+				Arrays.fill(parent1, 0, 20, (byte) 0);
+			} else {
+				content.iterate(parentRevisions[0], parentRevisions[0], false, pc);
+				System.arraycopy(pc.nodeid, 0, parent1, 0, 20);
+			}
+		}
+		if (parent2 != null) {
+			if (parentRevisions[1] == -1) {
+				Arrays.fill(parent2, 0, 20, (byte) 0);
+			} else {
+				content.iterate(parentRevisions[1], parentRevisions[1], false, pc);
+				System.arraycopy(pc.nodeid, 0, parent2, 0, 20);
+			}
+		}
+	}
+
+	// FIXME byte[] data might be too expensive, for few usecases it may be better to have intermediate Access object (when we don't need full data 
+	// instantly - e.g. calculate hash, or comparing two revisions
+	// XXX seems that RevlogStream is better place for this class. 
+	public interface Inspector {
+		// XXX boolean retVal to indicate whether to continue?
+		// TODO specify nodeid and data length, and reuse policy (i.e. if revlog stream doesn't reuse nodeid[] for each call) 
+		void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[/*20*/] nodeid, byte[] data);
+	}
+
+	/*
+	 * XXX think over if it's better to do either:
+	 * pw = getChangelog().new ParentWalker(); pw.init() and pass pw instance around as needed
+	 * or
+	 * add Revlog#getParentWalker(), static class, make cons() and #init package-local, and keep SoftReference to allow walker reuse.
+	 * 
+	 *  and yes, walker is not a proper name
+	 */
+	public final class ParentWalker {
+		private Map<Nodeid, Nodeid> firstParent;
+		private Map<Nodeid, Nodeid> secondParent;
+		private Set<Nodeid> allNodes;
+
+		public ParentWalker() {
+			firstParent = secondParent = Collections.emptyMap();
+			allNodes = Collections.emptySet();
+		}
+		
+		public void init() {
+			final RevlogStream stream = Revlog.this.content;
+			final int revisionCount = stream.revisionCount();
+			firstParent = new HashMap<Nodeid, Nodeid>(revisionCount);
+			secondParent = new HashMap<Nodeid, Nodeid>(firstParent.size() >> 1); // assume branches/merges are less frequent
+			allNodes = new LinkedHashSet<Nodeid>();
+			
+			Inspector insp = new Inspector() {
+				final Nodeid[] sequentialRevisionNodeids = new Nodeid[revisionCount];
+				int ix = 0;
+				public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
+					if (ix != revisionNumber) {
+						// XXX temp code, just to make sure I understand what's going on here
+						throw new IllegalStateException();
+					}
+					if (parent1Revision >= revisionNumber || parent2Revision >= revisionNumber) {
+						throw new IllegalStateException(); // sanity, revisions are sequential
+					}
+					final Nodeid nid = new Nodeid(nodeid, true);
+					sequentialRevisionNodeids[ix++] = nid;
+					allNodes.add(nid);
+					if (parent1Revision != -1) {
+						firstParent.put(nid, sequentialRevisionNodeids[parent1Revision]);
+						if (parent2Revision != -1) {
+							secondParent.put(nid, sequentialRevisionNodeids[parent2Revision]);
+						}
+					}
+				}
+			};
+			stream.iterate(0, -1, false, insp);
+		}
+		
+		public Set<Nodeid> allNodes() {
+			return Collections.unmodifiableSet(allNodes);
+		}
+		
+		// FIXME need to decide whether Nodeid(00 * 20) is always known or not
+		public boolean knownNode(Nodeid nid) {
+			return allNodes.contains(nid);
+		}
+
+		// null if none
+		public Nodeid firstParent(Nodeid nid) {
+			return firstParent.get(nid);
+		}
+
+		// never null, Nodeid.NULL if none known
+		public Nodeid safeFirstParent(Nodeid nid) {
+			Nodeid rv = firstParent(nid);
+			return rv == null ? Nodeid.NULL : rv;
+		}
+		
+		public Nodeid secondParent(Nodeid nid) {
+			return secondParent.get(nid);
+		}
+
+		public Nodeid safeSecondParent(Nodeid nid) {
+			Nodeid rv = secondParent(nid);
+			return rv == null ? Nodeid.NULL : rv;
+		}
+
+		public boolean appendParentsOf(Nodeid nid, Collection<Nodeid> c) {
+			Nodeid p1 = firstParent(nid);
+			boolean modified = false;
+			if (p1 != null) {
+				modified = c.add(p1);
+				Nodeid p2 = secondParent(nid);
+				if (p2 != null) {
+					modified = c.add(p2) || modified;
+				}
+			}
+			return modified;
+		}
+	}
+}