text: /*
   * 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 change 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();
      }
  
  }
  