tikhomirov@20: /*
tikhomirov@74:  * Copyright (c) 2010-2011 TMate Software Ltd
tikhomirov@74:  *  
tikhomirov@74:  * This program is free software; you can redistribute it and/or modify
tikhomirov@74:  * it under the terms of the GNU General Public License as published by
tikhomirov@74:  * the Free Software Foundation; version 2 of the License.
tikhomirov@74:  *
tikhomirov@74:  * This program is distributed in the hope that it will be useful,
tikhomirov@74:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
tikhomirov@74:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
tikhomirov@74:  * GNU General Public License for more details.
tikhomirov@74:  *
tikhomirov@74:  * For information on how to redistribute this software under
tikhomirov@74:  * the terms of a license other than GNU General Public License
tikhomirov@74:  * contact TMate Software at support@svnkit.com
tikhomirov@0:  */
tikhomirov@74: package org.tmatesoft.hg.core;
tikhomirov@0: 
tikhomirov@74: import static org.tmatesoft.hg.internal.DigestHelper.toHexString;
tikhomirov@31: 
tikhomirov@24: import java.util.Arrays;
tikhomirov@24: 
tikhomirov@20: 
tikhomirov@0: 
tikhomirov@0: /**
tikhomirov@74:  * A 20-bytes (40 characters) long hash value to identify a revision.
tikhomirov@74:  * @see http://mercurial.selenic.com/wiki/Nodeid
tikhomirov@74:  *
tikhomirov@74:  * @author Artem Tikhomirov
tikhomirov@74:  * @author TMate Software Ltd.
tikhomirov@0:  *
tikhomirov@0:  */
tikhomirov@24: public final class Nodeid {
tikhomirov@0: 	
tikhomirov@74: 	/**
tikhomirov@74: 	 * <b>nullid</b>, empty root revision.
tikhomirov@74: 	 */
tikhomirov@31: 	public static final Nodeid NULL = new Nodeid(new byte[20], false);
tikhomirov@74: 
tikhomirov@0: 	private final byte[] binaryData; 
tikhomirov@0: 
tikhomirov@24: 	/**
tikhomirov@74: 	 * @param binaryRepresentation - array of exactly 20 bytes
tikhomirov@28: 	 * @param shallClone - true if array is subject to future modification and shall be copied, not referenced 
tikhomirov@24: 	 */
tikhomirov@28: 	public Nodeid(byte[] binaryRepresentation, boolean shallClone) {
tikhomirov@0: 		// 5 int fields => 32 bytes
tikhomirov@0: 		// byte[20] => 48 bytes
tikhomirov@24: 		if (binaryRepresentation == null || binaryRepresentation.length != 20) {
tikhomirov@24: 			throw new IllegalArgumentException();
tikhomirov@24: 		}
tikhomirov@28: 		this.binaryData = shallClone ? binaryRepresentation.clone() : binaryRepresentation;
tikhomirov@0: 	}
tikhomirov@0: 
tikhomirov@24: 	@Override
tikhomirov@24: 	public int hashCode() {
tikhomirov@46: 		// digest (part thereof) seems to be nice candidate for the hashCode
tikhomirov@46: 		byte[] b = binaryData;
tikhomirov@46: 		return b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
tikhomirov@24: 	}
tikhomirov@24: 	
tikhomirov@24: 	@Override
tikhomirov@24: 	public boolean equals(Object o) {
tikhomirov@24: 		if (o instanceof Nodeid) {
tikhomirov@24: 			return Arrays.equals(this.binaryData, ((Nodeid) o).binaryData);
tikhomirov@24: 		}
tikhomirov@24: 		return false;
tikhomirov@22: 	}
tikhomirov@22: 
tikhomirov@22: 	public boolean equalsTo(byte[] buf) {
tikhomirov@24: 		return Arrays.equals(this.binaryData, buf);
tikhomirov@22: 	}
tikhomirov@22: 	
tikhomirov@0: 	@Override
tikhomirov@0: 	public String toString() {
tikhomirov@34: 		// XXX may want to output just single 0 for the NULL id?
tikhomirov@31: 		return toHexString(binaryData, 0, binaryData.length);
tikhomirov@0: 	}
tikhomirov@31: 
tikhomirov@31: 	public String shortNotation() {
tikhomirov@31: 		return toHexString(binaryData, 0, 6);
tikhomirov@31: 	}
tikhomirov@34: 	
tikhomirov@34: 	public boolean isNull() {
tikhomirov@34: 		if (this == NULL) {
tikhomirov@34: 			return true;
tikhomirov@34: 		}
tikhomirov@34: 		for (int i = 0; i < 20; i++) {
tikhomirov@34: 			if (this.binaryData[i] != 0) {
tikhomirov@34: 				return false;
tikhomirov@34: 			}
tikhomirov@34: 		}
tikhomirov@34: 		return true;
tikhomirov@34: 	}
tikhomirov@34: 
tikhomirov@74: 	// copy 
tikhomirov@74: 	public byte[] toByteArray() {
tikhomirov@41: 		return binaryData.clone();
tikhomirov@41: 	}
tikhomirov@41: 
tikhomirov@34: 	// primary difference with cons is handling of NULL id (this method returns constant)
tikhomirov@34: 	// always makes a copy of an array passed
tikhomirov@34: 	public static Nodeid fromBinary(byte[] binaryRepresentation, int offset) {
tikhomirov@34: 		if (binaryRepresentation == null || binaryRepresentation.length - offset < 20) {
tikhomirov@34: 			throw new IllegalArgumentException();
tikhomirov@34: 		}
tikhomirov@34: 		int i = 0;
tikhomirov@34: 		while (i < 20 && binaryRepresentation[offset+i] == 0) i++;
tikhomirov@34: 		if (i == 20) {
tikhomirov@34: 			return NULL;
tikhomirov@34: 		}
tikhomirov@34: 		if (offset == 0 && binaryRepresentation.length == 20) {
tikhomirov@34: 			return new Nodeid(binaryRepresentation, true);
tikhomirov@34: 		}
tikhomirov@34: 		byte[] b = new byte[20]; // create new instance if no other reasonable guesses possible
tikhomirov@34: 		System.arraycopy(binaryRepresentation, offset, b, 0, 20);
tikhomirov@34: 		return new Nodeid(b, false);
tikhomirov@34: 	}
tikhomirov@31: 
tikhomirov@0: 	public static Nodeid fromAscii(byte[] asciiRepresentation, int offset, int length) {
tikhomirov@24: 		if (length != 40) {
tikhomirov@24: 			throw new IllegalArgumentException();
tikhomirov@24: 		}
tikhomirov@24: 		byte[] data = new byte[20];
tikhomirov@31: 		boolean zeroBytes = true;
tikhomirov@0: 		for (int i = 0, j = offset; i < data.length; i++) {
tikhomirov@0: 			int hiNibble = Character.digit(asciiRepresentation[j++], 16);
tikhomirov@0: 			int lowNibble = Character.digit(asciiRepresentation[j++], 16);
tikhomirov@31: 			byte b = (byte) (((hiNibble << 4) | lowNibble) & 0xFF);
tikhomirov@31: 			data[i] = b;
tikhomirov@31: 			zeroBytes = zeroBytes && b == 0;
tikhomirov@31: 		}
tikhomirov@31: 		if (zeroBytes) {
tikhomirov@31: 			return NULL;
tikhomirov@0: 		}
tikhomirov@28: 		return new Nodeid(data, false);
tikhomirov@0: 	}
tikhomirov@0: }