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	/*
	* reserved comment block
	* DO NOT REMOVE OR ALTER!
	*/
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.sun.org.apache.xalan.internal.xsltc.dom;

	import java.io.Externalizable;
	import java.io.IOException;
	import java.io.ObjectInput;
	import java.io.ObjectOutput;

	import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;


	/**
	* @author Morten Jorgensen
	*/
	public class BitArray implements Externalizable {
	static final long serialVersionUID = -4876019880708377663L;

	private int[] _bits;
	private int _bitSize;
	private int _intSize;
	private int _mask;

	// This table is used to prevent expensive shift operations
	// (These operations are inexpensive on CPUs but very expensive on JVMs.)
	private final static int[] _masks = {
	0x80000000, 0x40000000, 0x20000000, 0x10000000,
	0x08000000, 0x04000000, 0x02000000, 0x01000000,
	0x00800000, 0x00400000, 0x00200000, 0x00100000,
	0x00080000, 0x00040000, 0x00020000, 0x00010000,
	0x00008000, 0x00004000, 0x00002000, 0x00001000,
	0x00000800, 0x00000400, 0x00000200, 0x00000100,
	0x00000080, 0x00000040, 0x00000020, 0x00000010,
	0x00000008, 0x00000004, 0x00000002, 0x00000001 };

	private final static boolean DEBUG_ASSERTIONS = false;

	/**
	* Constructor. Defines the initial size of the bit array (in bits).
	*/
	public BitArray() {
	this(32);
	}

	public BitArray(int size) {
	if (size < 32) size = 32;
	_bitSize = size;
	_intSize = (_bitSize >>> 5) + 1;
	_bits = new int[_intSize + 1];
	}

	public BitArray(int size, int[] bits) {
	if (size < 32) size = 32;
	_bitSize = size;
	_intSize = (_bitSize >>> 5) + 1;
	_bits = bits;
	}

	/**
	* Set the mask for this bit array. The upper 8 bits of this mask
	* indicate the DOM in which the nodes in this array belong.
	*/
	public void setMask(int mask) {
	_mask = mask;
	}

	/**
	* See setMask()
	*/
	public int getMask() {
	return(_mask);
	}

	/**
	* Returns the size of this bit array (in bits).
	*/
	public final int size() {
	return(_bitSize);
	}

	/**
	* Returns true if the given bit is set
	*/
	public final boolean getBit(int bit) {
	if (DEBUG_ASSERTIONS) {
	if (bit >= _bitSize) {
	throw new Error(
	"Programmer's assertion in BitArray.getBit");
	}
	}

	return((_bits[bit>>>5] & _masks[bit%32]) != 0);
	}

	/**
	* Returns the next set bit from a given position
	*/
	public final int getNextBit(int startBit) {
	for (int i = (startBit >>> 5) ; i<=_intSize; i++) {
	int bits = _bits[i];
	if (bits != 0) {
	for (int b = (startBit % 32); b<32; b++) {
	if ((bits & _masks[b]) != 0) {
	return((i << 5) + b);
	}
	}
	}
	startBit = 0;
	}
	return(DTMAxisIterator.END);
	}

	/**
	* This method returns the Nth bit that is set in the bit array. The
	* current position is cached in the following 4 variables and will
	* help speed up a sequence of next() call in an index iterator. This
	* method is a mess, but it is fast and it works, so don't fuck with it.
	*/
	private int _pos = Integer.MAX_VALUE;
	private int _node = 0;
	private int _int = 0;
	private int _bit = 0;

	public final int getBitNumber(int pos) {

	// Return last node if position we're looking for is the same
	if (pos == _pos) return(_node);

	// Start from beginning of position we're looking for is before
	// the point where we left off the last time.
	if (pos < _pos) {
	_int = _bit = _pos = 0;
	}

	// Scan through the bit array - skip integers that have no bits set
	for ( ; _int <= _intSize; _int++) {
	int bits = _bits[_int];
	if (bits != 0) { // Any bits set?
	for ( ; _bit < 32; _bit++) {
	if ((bits & _masks[_bit]) != 0) {
	if (++_pos == pos) {
	_node = ((_int << 5) + _bit) - 1;
	return (_node);
	}
	}
	}
	_bit = 0;
	}
	}
	return(0);
	}

	/**
	* Returns the integer array in which the bit array is contained
	*/
	public final int[] data() {
	return(_bits);
	}

	int _first = Integer.MAX_VALUE; // The index where first set bit is
	int _last = Integer.MIN_VALUE; // The _INTEGER INDEX_ where last set bit is

	/**
	* Sets a given bit
	*/
	public final void setBit(int bit) {
	if (DEBUG_ASSERTIONS) {
	if (bit >= _bitSize) {
	throw new Error(
	"Programmer's assertion in BitArray.getBit");
	}
	}

	if (bit >= _bitSize) return;
	final int i = (bit >>> 5);
	if (i < _first) _first = i;
	if (i > _last) _last = i;
	_bits[i] \|= _masks[bit % 32];
	}

	/**
	* Merge two bit arrays. This currently only works for nodes from
	* a single DOM (because there is only one _mask per array).
	*/
	public final BitArray merge(BitArray other) {
	// Take other array's bits if we have node set
	if (_last == -1) {
	_bits = other._bits;
	}
	// Only merge if other array has any bits set
	else if (other._last != -1) {
	int start = (_first < other._first) ? _first : other._first;
	int stop = (_last > other._last) ? _last : other._last;

	// Merge these bits into other array if other array is larger
	if (other._intSize > _intSize) {
	if (stop > _intSize) stop = _intSize;
	for (int i=start; i<=stop; i++)
	other._bits[i] \|= _bits[i];
	_bits = other._bits;
	}
	// Merge other bits into this array if this arrai is large/equal.
	else {
	if (stop > other._intSize) stop = other._intSize;
	for (int i=start; i<=stop; i++)
	_bits[i] \|= other._bits[i];
	}
	}
	return(this);
	}

	/**
	* Resizes the bit array - try to avoid using this method!!!
	*/
	public final void resize(int newSize) {
	if (newSize > _bitSize) {
	_intSize = (newSize >>> 5) + 1;
	final int[] newBits = new int[_intSize + 1];
	System.arraycopy(_bits, 0, newBits, 0, (_bitSize>>>5) + 1);
	_bits = newBits;
	_bitSize = newSize;
	}
	}

	public BitArray cloneArray() {
	return(new BitArray(_intSize, _bits));
	}

	public void writeExternal(ObjectOutput out) throws IOException {
	out.writeInt(_bitSize);
	out.writeInt(_mask);
	out.writeObject(_bits);
	out.flush();
	}

	/**
	* Read the whole tree from a file (serialized)
	*/
	public void readExternal(ObjectInput in)
	throws IOException, ClassNotFoundException {
	_bitSize = in.readInt();
	_intSize = (_bitSize >>> 5) + 1;
	_mask = in.readInt();
	_bits = (int[])in.readObject();
	}

	}

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