kitaev@213: /*
kitaev@213:  * Copyright (c) 2011 TMate Software Ltd
kitaev@213:  *  
kitaev@213:  * This program is free software; you can redistribute it and/or modify
kitaev@213:  * it under the terms of the GNU General Public License as published by
kitaev@213:  * the Free Software Foundation; version 2 of the License.
kitaev@213:  *
kitaev@213:  * This program is distributed in the hope that it will be useful,
kitaev@213:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
kitaev@213:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
kitaev@213:  * GNU General Public License for more details.
kitaev@213:  *
kitaev@213:  * For information on how to redistribute this software under
kitaev@213:  * the terms of a license other than GNU General Public License
kitaev@213:  * contact TMate Software at support@hg4j.com
kitaev@213:  */
kitaev@213: package org.tmatesoft.hg.internal;
kitaev@213: 
kitaev@213: import java.io.IOException;
kitaev@213: 
kitaev@213: 
kitaev@213: /**
kitaev@213:  *   
kitaev@213:  * @author Artem Tikhomirov
kitaev@213:  * @author TMate Software Ltd.
kitaev@213:  */
kitaev@213: public class ByteArrayDataAccess extends DataAccess {
kitaev@213: 
kitaev@213: 	private final byte[] data;
kitaev@213: 	private final int offset;
kitaev@213: 	private final int length;
kitaev@213: 	private int pos;
kitaev@213: 
kitaev@213: 	public ByteArrayDataAccess(byte[] data) {
kitaev@213: 		this(data, 0, data.length);
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	public ByteArrayDataAccess(byte[] data, int offset, int length) {
kitaev@213: 		this.data = data;
kitaev@213: 		this.offset = offset;
kitaev@213: 		this.length = length;
kitaev@213: 		pos = 0;
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	@Override
kitaev@213: 	public byte readByte() throws IOException {
kitaev@213: 		if (pos >= length) {
kitaev@213: 			throw new IOException();
kitaev@213: 		}
kitaev@213: 		return data[offset + pos++];
kitaev@213: 	}
kitaev@213: 	@Override
kitaev@213: 	public void readBytes(byte[] buf, int off, int len) throws IOException {
kitaev@213: 		if (len > (this.length - pos)) {
kitaev@213: 			throw new IOException();
kitaev@213: 		}
kitaev@213: 		System.arraycopy(data, pos, buf, off, len);
kitaev@213: 		pos += len;
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	@Override
kitaev@213: 	public ByteArrayDataAccess reset() {
kitaev@213: 		pos = 0;
kitaev@213: 		return this;
kitaev@213: 	}
kitaev@213: 	@Override
kitaev@213: 	public int length() {
kitaev@213: 		return length;
kitaev@213: 	}
kitaev@213: 	@Override
kitaev@213: 	public void seek(int offset) {
kitaev@213: 		pos = (int) offset;
kitaev@213: 	}
kitaev@213: 	@Override
kitaev@213: 	public void skip(int bytes) throws IOException {
kitaev@213: 		seek(pos + bytes);
kitaev@213: 	}
kitaev@213: 	@Override
kitaev@213: 	public boolean isEmpty() {
kitaev@213: 		return pos >= length;
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	//
kitaev@213: 	
kitaev@213: 	// when byte[] needed from DA, we may save few cycles and some memory giving this (otherwise unsafe) access to underlying data
kitaev@213: 	@Override
kitaev@213: 	public byte[] byteArray() {
kitaev@213: 		return data;
kitaev@213: 	}
kitaev@213: }