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 * Licensed to the Apache Software Foundation (ASF) under one or more

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 * 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

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 *      http://www.apache.org/licenses/LICENSE-2.0

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 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

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package com.sun.org.apache.xml.internal.dtm.ref;

import com.sun.org.apache.xml.internal.res.XMLErrorResources;

import com.sun.org.apache.xml.internal.res.XMLMessages;

/**

 * <code>ChunkedIntArray</code> is an extensible array of blocks of integers.

 * (I'd consider Vector, but it's unable to handle integers except by

 * turning them into Objects.)

 * <p>Making this a separate class means some call-and-return overhead. But

 * doing it all inline tends to be fragile and expensive in coder time,

 * not to mention driving up code size. If you want to inline it, feel free.

 * The Java text suggest that private and Final methods may be inlined,

 * and one can argue that this beast need not be made subclassable...</p>

 *

 * <p>%REVIEW% This has strong conceptual overlap with the IntVector class.

 * It would probably be a good thing to merge the two, when time permits.<p>

 */

final class ChunkedIntArray

{

  final int slotsize=4; // Locked, MUST be power of two in current code

  // Debugging tip: Cranking lowbits down to 4 or so is a good

  // way to pound on the array addressing code.

  static final int lowbits=10; // How many bits address within chunks

  static final int chunkalloc=1<<lowbits;

  static final int lowmask=chunkalloc-1;

  ChunksVector chunks=new ChunksVector();

  final int fastArray[] = new int[chunkalloc];

  int lastUsed=0;

  /**

   * Create a new CIA with specified record size. Currently record size MUST

   * be a power of two... and in fact is hardcoded to 4.

   */

  ChunkedIntArray(int slotsize)

  {

    if(this.slotsize<slotsize)

      throw new ArrayIndexOutOfBoundsException(XMLMessages.createXMLMessage(XMLErrorResources.ER_CHUNKEDINTARRAY_NOT_SUPPORTED, new Object[]{Integer.toString(slotsize)})); //"ChunkedIntArray("+slotsize+") not currently supported");

    else if (this.slotsize>slotsize)

      System.out.println("*****WARNING: ChunkedIntArray("+slotsize+") wasting "+(this.slotsize-slotsize)+" words per slot");

    chunks.addElement(fastArray);

  }

  /**

   * Append a 4-integer record to the CIA, starting with record 1. (Since

   * arrays are initialized to all-0, 0 has been reserved as the "unknown"

   * value in DTM.)

   * @return the index at which this record was inserted.

   */

  int appendSlot(int w0, int w1, int w2, int w3)

  {

    /*

    try

    {

      int newoffset = (lastUsed+1)*slotsize;

      fastArray[newoffset] = w0;

      fastArray[newoffset+1] = w1;

      fastArray[newoffset+2] = w2;

      fastArray[newoffset+3] = w3;

      return ++lastUsed;

    }

    catch(ArrayIndexOutOfBoundsException aioobe)

    */

    {

      final int slotsize=4;

      int newoffset = (lastUsed+1)*slotsize;

      int chunkpos = newoffset >> lowbits;

      int slotpos = (newoffset & lowmask);

      // Grow if needed

      if (chunkpos > chunks.size() - 1)

        chunks.addElement(new int[chunkalloc]);

      int[] chunk = chunks.elementAt(chunkpos);

      chunk[slotpos] = w0;

      chunk[slotpos+1] = w1;

      chunk[slotpos+2] = w2;

      chunk[slotpos+3] = w3;

      return ++lastUsed;

    }

  }

  /**

   * Retrieve an integer from the CIA by record number and column within

   * the record, both 0-based (though position 0 is reserved for special

   * purposes).

   * @param position int Record number

   * @param slotpos int Column number

   */

  int readEntry(int position, int offset) throws ArrayIndexOutOfBoundsException

  {

    /*

    try

    {

      return fastArray[(position*slotsize)+offset];

    }

    catch(ArrayIndexOutOfBoundsException aioobe)

    */

    {

      // System.out.println("Using slow read (1)");

      if (offset>=slotsize)

        throw new ArrayIndexOutOfBoundsException(XMLMessages.createXMLMessage(XMLErrorResources.ER_OFFSET_BIGGER_THAN_SLOT, null)); //"Offset bigger than slot");

      position*=slotsize;

      int chunkpos = position >> lowbits;

      int slotpos = position & lowmask;

      int[] chunk = chunks.elementAt(chunkpos);

      return chunk[slotpos + offset];

    }

  }

  // Check that the node at index "position" is not an ancestor

  // of the node at index "startPos". IF IT IS, DO NOT ACCEPT IT AND

  // RETURN -1. If position is NOT an ancestor, return position.

  // Special case: The Document node (position==0) is acceptable.

  //

  // This test supports DTM.getNextPreceding.

  int specialFind(int startPos, int position)

  {

          // We have to look all the way up the ancestor chain

          // to make sure we don't have an ancestor.

          int ancestor = startPos;

          while(ancestor > 0)

          {

                // Get the node whose index == ancestor

                ancestor*=slotsize;

                int chunkpos = ancestor >> lowbits;

                int slotpos = ancestor & lowmask;

                int[] chunk = chunks.elementAt(chunkpos);

                // Get that node's parent (Note that this assumes w[1]

                // is the parent node index. That's really a DTM feature

                // rather than a ChunkedIntArray feature.)

                ancestor = chunk[slotpos + 1];

                if(ancestor == position)

                         break;

          }

          if (ancestor <= 0)

          {

                  return position;

          }

          return -1;

  }

  /**

   * @return int index of highest-numbered record currently in use

   */

  int slotsUsed()

  {

    return lastUsed;

  }

  /** Disard the highest-numbered record. This is used in the string-buffer

   CIA; when only a single characters() chunk has been recieved, its index

   is moved into the Text node rather than being referenced by indirection

   into the text accumulator.

   */

  void discardLast()

  {

    --lastUsed;

  }

  /**

   * Overwrite the integer found at a specific record and column.

   * Used to back-patch existing records, most often changing their

   * "next sibling" reference from 0 (unknown) to something meaningful

   * @param position int Record number

   * @param offset int Column number

   * @param value int New contents

   */

  void writeEntry(int position, int offset, int value) throws ArrayIndexOutOfBoundsException

  {

    /*

    try

    {

      fastArray[( position*slotsize)+offset] = value;

    }

    catch(ArrayIndexOutOfBoundsException aioobe)

    */

    {

      if (offset >= slotsize)

        throw new ArrayIndexOutOfBoundsException(XMLMessages.createXMLMessage(XMLErrorResources.ER_OFFSET_BIGGER_THAN_SLOT, null)); //"Offset bigger than slot");

      position*=slotsize;

      int chunkpos = position >> lowbits;

      int slotpos = position & lowmask;

      int[] chunk = chunks.elementAt(chunkpos);

      chunk[slotpos + offset] = value; // ATOMIC!

    }

  }

  /**

   * Overwrite an entire (4-integer) record at the specified index.

   * Mostly used to create record 0, the Document node.

   * @param position integer Record number

   * @param w0 int

   * @param w1 int

   * @param w2 int

   * @param w3 int

   */

  void writeSlot(int position, int w0, int w1, int w2, int w3)

  {

      position *= slotsize;

      int chunkpos = position >> lowbits;

      int slotpos = (position & lowmask);

    // Grow if needed

    if (chunkpos > chunks.size() - 1)

      chunks.addElement(new int[chunkalloc]);

    int[] chunk = chunks.elementAt(chunkpos);

    chunk[slotpos] = w0;

    chunk[slotpos + 1] = w1;

    chunk[slotpos + 2] = w2;

    chunk[slotpos + 3] = w3;

  }

  /**

   * Retrieve the contents of a record into a user-supplied buffer array.

   * Used to reduce addressing overhead when code will access several

   * columns of the record.

   * @param position int Record number

   * @param buffer int[] Integer array provided by user, must be large enough

   * to hold a complete record.

   */

  void readSlot(int position, int[] buffer)

  {

    /*

    try

    {

      System.arraycopy(fastArray, position*slotsize, buffer, 0, slotsize);

    }

    catch(ArrayIndexOutOfBoundsException aioobe)

    */

    {

      // System.out.println("Using slow read (2): "+position);

      position *= slotsize;

      int chunkpos = position >> lowbits;

      int slotpos = (position & lowmask);

      // Grow if needed

      if (chunkpos > chunks.size() - 1)

        chunks.addElement(new int[chunkalloc]);

      int[] chunk = chunks.elementAt(chunkpos);

      System.arraycopy(chunk,slotpos,buffer,0,slotsize);

    }

  }

  class ChunksVector

  {

    final int BLOCKSIZE = 64;

    int[] m_map[] = new int[BLOCKSIZE][];

    int m_mapSize = BLOCKSIZE;

    int pos = 0;

    ChunksVector()

    {

    }

    final int size()

    {

      return pos;

    }

    void addElement(int[] value)

    {

      if(pos >= m_mapSize)

      {

        int orgMapSize = m_mapSize;

        while(pos >= m_mapSize)

          m_mapSize+=BLOCKSIZE;

        int[] newMap[] = new int[m_mapSize][];

        System.arraycopy(m_map, 0, newMap, 0, orgMapSize);

        m_map = newMap;

      }

      // For now, just do a simple append.  A sorted insert only

      // makes sense if we're doing an binary search or some such.

      m_map[pos] = value;

      pos++;

    }

    final int[] elementAt(int pos)

    {

      return m_map[pos];

    }

  }

}