tikhomirov@51: /*
tikhomirov@51:  * Copyright (c) 2011 Artem Tikhomirov 
tikhomirov@51:  */
tikhomirov@51: package com.tmate.hgkit.fs;
tikhomirov@51: 
tikhomirov@51: import java.io.IOException;
tikhomirov@51: 
tikhomirov@51: /**
tikhomirov@51:  *
tikhomirov@51:  * @author artem
tikhomirov@51:  */
tikhomirov@51: public class ByteArrayDataAccess extends DataAccess {
tikhomirov@51: 
tikhomirov@51: 	private final byte[] data;
tikhomirov@51: 	private final int offset;
tikhomirov@51: 	private final int length;
tikhomirov@51: 	private int pos;
tikhomirov@51: 
tikhomirov@51: 	public ByteArrayDataAccess(byte[] data) {
tikhomirov@51: 		this(data, 0, data.length);
tikhomirov@51: 	}
tikhomirov@51: 
tikhomirov@51: 	public ByteArrayDataAccess(byte[] data, int offset, int length) {
tikhomirov@51: 		this.data = data;
tikhomirov@51: 		this.offset = offset;
tikhomirov@51: 		this.length = length;
tikhomirov@51: 		pos = 0;
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	@Override
tikhomirov@51: 	public byte readByte() throws IOException {
tikhomirov@51: 		if (pos >= length) {
tikhomirov@51: 			throw new IOException();
tikhomirov@51: 		}
tikhomirov@51: 		return data[offset + pos++];
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@51: 	public void readBytes(byte[] buf, int off, int len) throws IOException {
tikhomirov@51: 		if (len > (this.length - pos)) {
tikhomirov@51: 			throw new IOException();
tikhomirov@51: 		}
tikhomirov@51: 		System.arraycopy(data, pos, buf, off, len);
tikhomirov@51: 		pos += len;
tikhomirov@51: 	}
tikhomirov@51: 
tikhomirov@51: 	@Override
tikhomirov@51: 	public void reset() {
tikhomirov@51: 		pos = 0;
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@51: 	public long length() {
tikhomirov@51: 		return length;
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@51: 	public void seek(long offset) {
tikhomirov@51: 		pos = (int) offset;
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@51: 	public void skip(int bytes) throws IOException {
tikhomirov@51: 		seek(pos + bytes);
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@51: 	public boolean isEmpty() {
tikhomirov@51: 		return pos >= length;
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	//
tikhomirov@51: 	
tikhomirov@51: 	// when byte[] needed from DA, we may save few cycles and some memory giving this (otherwise unsafe) access to underlying data
tikhomirov@51: 	@Override
tikhomirov@51: 	public byte[] byteArray() {
tikhomirov@51: 		return data;
tikhomirov@51: 	}
tikhomirov@51: }