--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/DirstateBuilder.java	Fri Jan 11 18:12:39 2013 +0100
@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2012-2013 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;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.WritableByteChannel;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.tmatesoft.hg.core.Nodeid;
+import org.tmatesoft.hg.repo.HgDirstate;
+import org.tmatesoft.hg.repo.HgManifest.Flags;
+import org.tmatesoft.hg.util.Path;
+
+/**
+ * Facility to build a dirstate file as described in {@linkplain http://mercurial.selenic.com/wiki/DirState}
+ * 
+ * @see http://mercurial.selenic.com/wiki/DirState
+ * @see HgDirstate
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public class DirstateBuilder {
+	private List<HgDirstate.Record> normal = new ArrayList<HgDirstate.Record>();
+	private Nodeid parent1, parent2;
+	private final EncodingHelper encodingHelper;
+	
+	public DirstateBuilder(EncodingHelper encHelper) {
+		encodingHelper = encHelper;
+	}
+	
+	public void parents(Nodeid p1, Nodeid p2) {
+		parent1 = p1 == null ? Nodeid.NULL : p1;
+		parent2 = p2 == null ? Nodeid.NULL : p2;
+	}
+	
+	public void recordNormal(Path fname, Flags flags, int bytesWritten) {
+		// Mercurial seems to write "n   0  -1   unset fname" on `hg --clean co -rev <earlier rev>`
+		// and the reason for 'force lookup' I suspect is a slight chance of simultaneous modification
+		// of the file by user that doesn't alter its size the very second dirstate is being written
+		// (or the file is being updated and the update brought in changes that didn't alter the file size - 
+		// with size and timestamp set, later `hg status` won't notice these changes)
+		
+		// However, as long as we use this class to write clean copies of the files, we can put all the fields
+		// right away.
+		int fmode = flags == Flags.RegularFile ? 0666 : 0777; // FIXME actual unix flags
+		int mtime = (int) (System.currentTimeMillis() / 1000);
+		normal.add(new HgDirstate.Record(fmode, bytesWritten, mtime,fname, null));
+		
+	}
+
+	public void serialize(WritableByteChannel dest) throws IOException {
+		assert parent1 != null : "Parent(s) of the working directory shall be set first";
+		ByteBuffer bb = ByteBuffer.allocate(256);
+		bb.put(parent1.toByteArray());
+		bb.put(parent2.toByteArray());
+		bb.flip();
+		// header
+		int written = dest.write(bb);
+		if (written != bb.limit()) {
+			throw new IOException("Incomplete write");
+		}
+		bb.clear();
+		// entries
+		for (HgDirstate.Record r : normal) {
+			// normal entry is 1+4+4+4+4+fname.length bytes
+			byte[] fname = encodingHelper.toDirstate(r.name().toString());
+			bb = ensureCapacity(bb, 17 + fname.length);
+			bb.put((byte) 'n');
+			bb.putInt(r.mode());
+			bb.putInt(r.size());
+			bb.putInt(r.modificationTime());
+			bb.putInt(fname.length);
+			bb.put(fname);
+			bb.flip();
+			written = dest.write(bb);
+			if (written != bb.limit()) {
+				throw new IOException("Incomplete write");
+			}
+			bb.clear();
+		}
+	}
+
+	private static ByteBuffer ensureCapacity(ByteBuffer buf, int cap) {
+		if (buf.capacity() >= cap) {
+			return buf;
+		}
+		return ByteBuffer.allocate(cap);
+	}
+}