tikhomirov@329: /*
tikhomirov@329:  * Copyright (c) 2011 TMate Software Ltd
tikhomirov@329:  *  
tikhomirov@329:  * This program is free software; you can redistribute it and/or modify
tikhomirov@329:  * it under the terms of the GNU General Public License as published by
tikhomirov@329:  * the Free Software Foundation; version 2 of the License.
tikhomirov@329:  *
tikhomirov@329:  * This program is distributed in the hope that it will be useful,
tikhomirov@329:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
tikhomirov@329:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
tikhomirov@329:  * GNU General Public License for more details.
tikhomirov@329:  *
tikhomirov@329:  * For information on how to redistribute this software under
tikhomirov@329:  * the terms of a license other than GNU General Public License
tikhomirov@329:  * contact TMate Software at support@hg4j.com
tikhomirov@329:  */
tikhomirov@329: package org.tmatesoft.hg.internal;
tikhomirov@329: 
tikhomirov@329: import java.io.IOException;
tikhomirov@329: import java.util.ArrayList;
tikhomirov@329: 
tikhomirov@329: /**
tikhomirov@329:  * @see http://mercurial.selenic.com/wiki/BundleFormat, in Changelog group description
tikhomirov@329:  * 
tikhomirov@329:  * range [start..end] in original source gets replaced with data of length (do not keep, use data.length instead)
tikhomirov@329:  * range [end(i)..start(i+1)] is copied from the source
tikhomirov@329:  * 
tikhomirov@329:  * @author Artem Tikhomirov
tikhomirov@329:  * @author TMate Software Ltd.
tikhomirov@329:  */
tikhomirov@329: public final class Patch {
tikhomirov@329: 	private final IntVector starts, ends;
tikhomirov@329: 	private final ArrayList<byte[]> data;
tikhomirov@329: 	
tikhomirov@329: 	public Patch() {
tikhomirov@329: 		starts = new IntVector();
tikhomirov@329: 		ends = new IntVector();
tikhomirov@329: 		data = new ArrayList<byte[]>();
tikhomirov@329: 	}
tikhomirov@329: 	
tikhomirov@329: 	public int count() {
tikhomirov@329: 		return data.size();
tikhomirov@329: 	}
tikhomirov@329: 
tikhomirov@329: 	// number of bytes this patch will add (or remove, if negative) from the base revision
tikhomirov@329: 	private int patchSizeDelta() {
tikhomirov@329: 		int rv = 0;
tikhomirov@329: 		int prevEnd = 0;
tikhomirov@329: 		for (int i = 0, x = data.size(); i < x; i++) {
tikhomirov@329: 			final int start = starts.get(i);
tikhomirov@329: 			final int len = data.get(i).length;
tikhomirov@329: 			rv += start - prevEnd; // would copy from original
tikhomirov@329: 			rv += len; // and add new
tikhomirov@329: 			prevEnd = ends.get(i);
tikhomirov@329: 		}
tikhomirov@329: 		rv -= prevEnd;
tikhomirov@329: 		return rv;
tikhomirov@329: 	}
tikhomirov@329: 	
tikhomirov@329: 	public byte[] apply(DataAccess baseRevisionContent, int outcomeLen) throws IOException {
tikhomirov@329: 		if (outcomeLen == -1) {
tikhomirov@329: 			outcomeLen = baseRevisionContent.length() + patchSizeDelta();
tikhomirov@329: 		}
tikhomirov@329: 		int prevEnd = 0, destIndex = 0;
tikhomirov@329: 		byte[] rv = new byte[outcomeLen];
tikhomirov@329: 		for (int i = 0, x = data.size(); i < x; i++) {
tikhomirov@329: 			final int start = starts.get(i);
tikhomirov@329: 			baseRevisionContent.seek(prevEnd);
tikhomirov@329: 			// copy source bytes that were not modified (up to start of the record)
tikhomirov@329: 			baseRevisionContent.readBytes(rv, destIndex, start - prevEnd);
tikhomirov@329: 			destIndex += start - prevEnd;
tikhomirov@329: 			// insert new data from the patch, if any
tikhomirov@329: 			byte[] d = data.get(i);
tikhomirov@329: 			System.arraycopy(d, 0, rv, destIndex, d.length);
tikhomirov@329: 			destIndex += d.length;
tikhomirov@329: 			prevEnd = ends.get(i);
tikhomirov@329: 		}
tikhomirov@329: 		baseRevisionContent.seek(prevEnd);
tikhomirov@329: 		// copy everything in the source past last record's end
tikhomirov@329: 		baseRevisionContent.readBytes(rv, destIndex, (int) (baseRevisionContent.length() - prevEnd));
tikhomirov@329: 		return rv;
tikhomirov@329: 	}
tikhomirov@329: 	
tikhomirov@329: 	public void clear() {
tikhomirov@329: 		starts.clear();
tikhomirov@329: 		ends.clear();
tikhomirov@329: 		data.clear();
tikhomirov@329: 	}
tikhomirov@329: 	
tikhomirov@329: 	/**
tikhomirov@329: 	 * Initialize instance from stream. Any previous patch information (i.e. if instance if reused) is cleared first.
tikhomirov@329: 	 * Read up to the end of DataAccess and interpret data as patch records.
tikhomirov@329: 	 */
tikhomirov@329: 	public void read(DataAccess da) throws IOException {
tikhomirov@329: 		clear();
tikhomirov@329: 		while (!da.isEmpty()) {
tikhomirov@329: 			readOne(da);
tikhomirov@329: 		}
tikhomirov@329: 	}
tikhomirov@329: 
tikhomirov@329: 	/**
tikhomirov@329: 	 * Caller is responsible to ensure stream got some data to read
tikhomirov@329: 	 */
tikhomirov@329: 	public void readOne(DataAccess da) throws IOException {
tikhomirov@329: 		int s = da.readInt();
tikhomirov@329: 		int e = da.readInt();
tikhomirov@329: 		int len = da.readInt();
tikhomirov@329: 		byte[] src = new byte[len];
tikhomirov@329: 		da.readBytes(src, 0, len);
tikhomirov@329: 		starts.add(s);
tikhomirov@329: 		ends.add(e);
tikhomirov@329: 		data.add(src);
tikhomirov@329: 	}
tikhomirov@329: 
tikhomirov@329: /*
tikhomirov@329: 	private void add(Patch another, int index) {
tikhomirov@329: 		starts.add(another.starts.get(index));
tikhomirov@329: 		ends.add(another.ends.get(index));
tikhomirov@329: 		data.add(another.data.get(index));
tikhomirov@329: 	}
tikhomirov@329: 
tikhomirov@329: 	/**
tikhomirov@329: 	 * Modify this patch with subsequent patch 
tikhomirov@329: 	 * /
tikhomirov@329: 	public void apply(Patch another) {
tikhomirov@329: 		Patch r = new Patch();
tikhomirov@329: 		int p1AppliedPos = 0;
tikhomirov@329: 		int p1PrevEnd = 0;
tikhomirov@329: 		for (int i = 0, j = 0, iMax = another.count(), jMax = this.count(); i < iMax; i++) {
tikhomirov@329: 			int newerPatchEntryStart = another.starts.get(i);
tikhomirov@329: 			int olderPatchEntryEnd;
tikhomirov@329: 			
tikhomirov@329: 			while (j < jMax) {
tikhomirov@329: 				if (starts.get(j) < newerPatchEntryStart) {
tikhomirov@329: 					if (starts.get(j)+data.get(j).length <= newerPatchEntryStart) {
tikhomirov@329: 						r.add(this, j);
tikhomirov@329: 					} else {
tikhomirov@329: 						int newLen = newerPatchEntryStart - starts.get(j);
tikhomirov@329: 						int newEnd = ends.get(j) <= newerPatchEntryStart ? ends.get(j) : newerPatchEntryStart; 
tikhomirov@329: 						r.add(starts.get(j), newEnd, data.get(j), newLen);
tikhomirov@329: 						break;
tikhomirov@329: 					}
tikhomirov@329: 				}
tikhomirov@329: 				p1AppliedPos += starts.get(j) - p1PrevEnd;
tikhomirov@329: 				p1AppliedPos += data.get(j).length;
tikhomirov@329: 				p1PrevEnd = ends.get(j);
tikhomirov@329: 				j++;
tikhomirov@329: 			}
tikhomirov@329: 			r.add(newerPatchEntryStart, another.ends.get(i), another.data.get(i));
tikhomirov@329: 			p1AppliedPos += newerPatchEntryStart + p1PrevEnd - another.data.get(i).length;
tikhomirov@329: 			// either j == jMax and another(i, i+1, ..., iMax) need to be just copied
tikhomirov@329: 			// or new patch entry starts before end of one of original patch entries
tikhomirov@329: 			if (olderPatchEntryEnd > (destPosition + newerPatchEntryStart)) {
tikhomirov@329: 				destPosition += starts.get(j) - prevEnd; // count those in the original stream up to old patch start
tikhomirov@329: 				int newLen = newerPatchEntryStart - destPosition;
tikhomirov@329: 			}
tikhomirov@329: 		}
tikhomirov@329: 	}
tikhomirov@329: */
tikhomirov@329: }