Buffer.java

/*
 * Javolution - Java(TM) Solution for Real-Time and Embedded Systems
 * Copyright (C) 2005 - Javolution (http://javolution.org/)
 * All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software is
 * freely granted, provided that this notice is preserved.
 */
package j2me.nio;

/**
 * Clean-room implementation of Buffer to support 
 * <code>javolution.util.Struct</code> when <code>java.nio</code> is
 * not available.
 */
public abstract class Buffer {
    final int _capacity;

    int _limit;

    int _position;

    int _mark;

    Buffer(int capacity, int limit, int position, int mark) {
        _capacity = capacity;
        _limit = limit;
        _position = position;
        _mark = mark;
    }

    public final int capacity() {
        return _capacity;
    }

    public final Buffer clear() {
        _limit = _capacity;
        _position = 0;
        _mark = -1;
        return this;
    }

    public final Buffer flip() {
        _limit = _position;
        _position = 0;
        _mark = -1;
        return this;
    }

    public final boolean hasRemaining() {
        return _limit - _position > 0;
    }

    public boolean isReadOnly() {
        return false;
    }

    public final int limit() {
        return _limit;
    }

    public final Buffer limit(int newLimit) {
        if ((newLimit < 0) || (newLimit > _capacity)) {
            throw new IllegalArgumentException();
        }
        if (newLimit < _mark) {
            _mark = -1;
        }
        if (_position > newLimit) {
            _position = newLimit;
        }
        _limit = newLimit;
        return this;
    }

    public final Buffer mark() {
        _mark = _position;
        return this;
    }

    public final int position() {
        return _position;
    }

    public final Buffer position(int newPosition) {
        if ((newPosition < 0) || (newPosition > _limit)) {
            throw new IllegalArgumentException();
        }

        if (newPosition <= _mark) {
            _mark = -1;
        }
        _position = newPosition;
        return this;
    }

    public final int remaining() {
        return _limit - _position;
    }

    public final Buffer reset() {
        if (_mark == -1) {
            throw new InvalidMarkException();
        }
        _position = _mark;
        return this;
    }

    public final Buffer rewind() {
        _position = 0;
        _mark = -1;
        return this;
    }
}