tikhomirov@20: /*
tikhomirov@20:  * Copyright (c) 2010, 2011 Artem Tikhomirov 
tikhomirov@0:  */
tikhomirov@0: package com.tmate.hgkit.ll;
tikhomirov@0: 
tikhomirov@20: 
tikhomirov@0: 
tikhomirov@0: /**
tikhomirov@20:  * Whether to store fixed size array (20 bytes) - ease of manipulation (e.g. hashcode/equals), or 
tikhomirov@20:  * memory effective - reuse supplied array, keep significant bits only?
tikhomirov@20:  * Fixed size array looks most appealing to me now - I doubt one can save any significant amount of memory. 
tikhomirov@20:  * There'd always 20 non-zero bytes, the difference is only for any extra bytes one may pass to constructor  
tikhomirov@0:  * @author artem
tikhomirov@0:  *
tikhomirov@0:  */
tikhomirov@20: public final class Nodeid implements Comparable<Nodeid> {
tikhomirov@0: 	
tikhomirov@0: 	public static int NULLREV = -1;
tikhomirov@0: 	private final byte[] binaryData; 
tikhomirov@0: 
tikhomirov@0: 	public Nodeid(byte[] binaryRepresentation) {
tikhomirov@0: 		// 5 int fields => 32 bytes
tikhomirov@0: 		// byte[20] => 48 bytes
tikhomirov@0: 		this.binaryData = binaryRepresentation;
tikhomirov@0: 	}
tikhomirov@0: 
tikhomirov@20: 	// instead of hashCode/equals
tikhomirov@20: 	public int compareTo(Nodeid o) {
tikhomirov@22: 		return equals(this.binaryData, o.binaryData) ? 0 : -1;
tikhomirov@22: 	}
tikhomirov@22: 
tikhomirov@22: 	public boolean equalsTo(byte[] buf) {
tikhomirov@22: 		return equals(this.binaryData, buf);
tikhomirov@22: 	}
tikhomirov@22: 	
tikhomirov@22: 	private static boolean equals(byte[] a1, byte[] a2) {
tikhomirov@22: 		if (a1 == null || a1.length < 20 || a2 == null || a2.length < 20) {
tikhomirov@22: 			throw new IllegalArgumentException();
tikhomirov@20: 		}
tikhomirov@22: 		// assume significant bits are at the end of the array
tikhomirov@22: 		final int s1 = a1.length - 20, s2 = a2.length - 20;
tikhomirov@22: 		for (int i = 0; i < 20; i++) {
tikhomirov@22: 			if (a1[s1+i] != a2[s2+i]) {
tikhomirov@22: 				return false;
tikhomirov@22: 			}
tikhomirov@20: 		}
tikhomirov@22: 		return true;
tikhomirov@20: 	}
tikhomirov@20: 
tikhomirov@0: 	@Override
tikhomirov@0: 	public String toString() {
tikhomirov@13: 		return new DigestHelper().toHexString(binaryData, 0, binaryData.length);
tikhomirov@0: 	}
tikhomirov@20: 	
tikhomirov@0: 	// binascii.unhexlify()
tikhomirov@0: 	public static Nodeid fromAscii(byte[] asciiRepresentation, int offset, int length) {
tikhomirov@0: 		assert length % 2 == 0; // Python's binascii.hexlify convert each byte into 2 digits
tikhomirov@9: 		byte[] data = new byte[length >>> 1]; // XXX use known size instead? nodeid is always 20 bytes
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@0: 			data[i] = (byte) (((hiNibble << 4) | lowNibble) & 0xFF);
tikhomirov@0: 		}
tikhomirov@0: 		return new Nodeid(data);
tikhomirov@0: 	}
tikhomirov@0: }