tikhomirov@20: /*
tikhomirov@20:  * Copyright (c) 2010, 2011 Artem Tikhomirov 
tikhomirov@0:  */
tikhomirov@0: package com.tmate.hgkit.ll;
tikhomirov@0: 
tikhomirov@31: import static com.tmate.hgkit.ll.DigestHelper.toHexString;
tikhomirov@31: 
tikhomirov@24: import java.util.Arrays;
tikhomirov@24: 
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@24: public final class Nodeid {
tikhomirov@0: 	
tikhomirov@31: 	public static final Nodeid NULL = new Nodeid(new byte[20], false);
tikhomirov@0: 	private final byte[] binaryData; 
tikhomirov@0: 
tikhomirov@24: 	/**
tikhomirov@28: 	 * @param binaryRepresentation - byte[20], kept by reference
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@24: 		// TODO consider own impl, especially if byte[] get replaced with 5 ints
tikhomirov@24: 		return Arrays.hashCode(binaryData);
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@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@31: 
tikhomirov@0: 	// binascii.unhexlify()
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: }