xalan/serializer/2.7.2 : org/apache/xml/utils/SuballocatedByteVector.java

SuballocatedByteVector
http://xml.apache.org/xalan-j/: Serializer to write out XML, HTML etc. as a stream of characters from an input DOM or from input SAX events. (The Apache Software Foundation)
The Apache Software License, Version 2.0
/*
 * 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.
 */
/*
 * $Id: SuballocatedByteVector.java 468655 2006-10-28 07:12:06Z minchau $
 */
package org.apache.xml.utils;

A very simple table that stores a list of byte. Very similar API to our
IntVector class (same API); different internal storage.
This version uses an array-of-arrays solution. Read/write access is thus
a bit slower than the simple IntVector, and basic storage is a trifle
higher due to the top-level array -- but appending is O(1) fast rather
than O(N**2) slow, which will swamp those costs in situations where
long vectors are being built up.
Known issues:
Some methods are private because they haven't yet been tested properly.
If an element has not been set (because we skipped it), its value will
initially be 0. Shortening the vector does not clear old storage; if you
then skip values and setElementAt a higher index again, you may see old data
reappear in the truncated-and-restored section. Doing anything else would
have performance costs.
@xsl.usage internal/**
 * A very simple table that stores a list of byte. Very similar API to our
 * IntVector class (same API); different internal storage.
 * 
 * This version uses an array-of-arrays solution. Read/write access is thus
 * a bit slower than the simple IntVector, and basic storage is a trifle
 * higher due to the top-level array -- but appending is O(1) fast rather
 * than O(N**2) slow, which will swamp those costs in situations where
 * long vectors are being built up.
 * 
 * Known issues:
 * 
 * Some methods are private because they haven't yet been tested properly.
 * 
 * If an element has not been set (because we skipped it), its value will
 * initially be 0. Shortening the vector does not clear old storage; if you
 * then skip values and setElementAt a higher index again, you may see old data
 * reappear in the truncated-and-restored section. Doing anything else would
 * have performance costs.
 * @xsl.usage internal
 */
public class SuballocatedByteVector
{
  Size of blocks to allocate          /** Size of blocks to allocate          */
  protected int m_blocksize;
  
  Number of blocks to (over)allocate by /** Number of blocks to (over)allocate by */
  protected  int m_numblocks=32;
  
  Array of arrays of bytes          /** Array of arrays of bytes          */
  protected byte m_map[][];

  Number of bytes in array          /** Number of bytes in array          */
  protected int m_firstFree = 0;

  "Shortcut" handle to m_map[0] /** "Shortcut" handle to m_map[0] */
  protected byte m_map0[];

  Default constructor.  Note that the default
block size is very small, for small lists.
/**
   * Default constructor.  Note that the default
   * block size is very small, for small lists.
   */
  public SuballocatedByteVector()
  {
    this(2048);
  }

  Construct a ByteVector, using the given block size.
Params: blocksize – Size of block to allocate/**
   * Construct a ByteVector, using the given block size.
   *
   * @param blocksize Size of block to allocate
   */
  public SuballocatedByteVector(int blocksize)
  {
    m_blocksize = blocksize;
    m_map0=new byte[blocksize];
    m_map = new byte[m_numblocks][];
    m_map[0]=m_map0;
  }
  
  Construct a ByteVector, using the given block size.
Params: blocksize – Size of block to allocate/**
   * Construct a ByteVector, using the given block size.
   *
   * @param blocksize Size of block to allocate
   */
  public SuballocatedByteVector(int blocksize, int increaseSize)
  {
    // increaseSize not currently used.
    this(blocksize);
  }


  Get the length of the list.
Returns: length of the list/**
   * Get the length of the list.
   *
   * @return length of the list
   */
  public int size()
  {
    return m_firstFree;
  }
  
  Set the length of the list.
Returns: length of the list/**
   * Set the length of the list.
   *
   * @return length of the list
   */
  private  void setSize(int sz)
  {
    if(m_firstFree<sz)
      m_firstFree = sz;
  }

  Append a byte onto the vector.
Params: value – Byte to add to the list/**
   * Append a byte onto the vector.
   *
   * @param value Byte to add to the list 
   */
  public  void addElement(byte value)
  {
    if(m_firstFree<m_blocksize)
      m_map0[m_firstFree++]=value;
    else
    {
      int index=m_firstFree/m_blocksize;
      int offset=m_firstFree%m_blocksize;
      ++m_firstFree;

      if(index>=m_map.length)
      {
        int newsize=index+m_numblocks;
        byte[][] newMap=new byte[newsize][];
        System.arraycopy(m_map, 0, newMap, 0, m_map.length);
        m_map=newMap;
      }
      byte[] block=m_map[index];
      if(null==block)
        block=m_map[index]=new byte[m_blocksize];
      block[offset]=value;
    }
  }
  
  Append several byte values onto the vector.
Params: value – Byte to add to the list/**
   * Append several byte values onto the vector.
   *
   * @param value Byte to add to the list 
   */
  private  void addElements(byte value, int numberOfElements)
  {
    if(m_firstFree+numberOfElements<m_blocksize)
      for (int i = 0; i < numberOfElements; i++) 
      {
        m_map0[m_firstFree++]=value;
      }
    else
    {
      int index=m_firstFree/m_blocksize;
      int offset=m_firstFree%m_blocksize;
      m_firstFree+=numberOfElements;
      while( numberOfElements>0)
      {
        if(index>=m_map.length)
        {
          int newsize=index+m_numblocks;
          byte[][] newMap=new byte[newsize][];
          System.arraycopy(m_map, 0, newMap, 0, m_map.length);
          m_map=newMap;
        }
        byte[] block=m_map[index];
        if(null==block)
          block=m_map[index]=new byte[m_blocksize];
        int copied=(m_blocksize-offset < numberOfElements)
          ? m_blocksize-offset : numberOfElements;
        numberOfElements-=copied;
        while(copied-- > 0)
          block[offset++]=value;

        ++index;offset=0;
      }
    }
  }
  
  Append several slots onto the vector, but do not set the values.
Note: "Not Set" means the value is unspecified.
Params: numberOfElements – /**
   * Append several slots onto the vector, but do not set the values.
   * Note: "Not Set" means the value is unspecified.
   *
   * @param numberOfElements
   */
  private  void addElements(int numberOfElements)
  {
    int newlen=m_firstFree+numberOfElements;
    if(newlen>m_blocksize)
    {
      int index=m_firstFree%m_blocksize;
      int newindex=(m_firstFree+numberOfElements)%m_blocksize;
      for(int i=index+1;i<=newindex;++i)
        m_map[i]=new byte[m_blocksize];
    }
    m_firstFree=newlen;
  }
  
  Inserts the specified node in this vector at the specified index.
Each component in this vector with an index greater or equal to
the specified index is shifted upward to have an index one greater
than the value it had previously.
Insertion may be an EXPENSIVE operation!
Params: value – Byte to insert
at – Index of where to insert/**
   * Inserts the specified node in this vector at the specified index.
   * Each component in this vector with an index greater or equal to
   * the specified index is shifted upward to have an index one greater
   * than the value it had previously.
   *
   * Insertion may be an EXPENSIVE operation!
   *
   * @param value Byte to insert
   * @param at Index of where to insert 
   */
  private  void insertElementAt(byte value, int at)
  {
    if(at==m_firstFree)
      addElement(value);
    else if (at>m_firstFree)
    {
      int index=at/m_blocksize;
      if(index>=m_map.length)
      {
        int newsize=index+m_numblocks;
        byte[][] newMap=new byte[newsize][];
        System.arraycopy(m_map, 0, newMap, 0, m_map.length);
        m_map=newMap;
      }
      byte[] block=m_map[index];
      if(null==block)
        block=m_map[index]=new byte[m_blocksize];
      int offset=at%m_blocksize;
      block[offset]=value;
      m_firstFree=offset+1;
    }
    else
    {
      int index=at/m_blocksize;
      int maxindex=m_firstFree+1/m_blocksize;
      ++m_firstFree;
      int offset=at%m_blocksize;
      byte push;
      
      // ***** Easier to work down from top?
      while(index<=maxindex)
      {
        int copylen=m_blocksize-offset-1;
        byte[] block=m_map[index];
        if(null==block)
        {
          push=0;
          block=m_map[index]=new byte[m_blocksize];
        }
        else
        {
          push=block[m_blocksize-1];
          System.arraycopy(block, offset , block, offset+1, copylen);
        }
        block[offset]=value;
        value=push;
        offset=0;
        ++index;
      }
    }
  }

  Wipe it out. 
/**
   * Wipe it out. 
   */
  public void removeAllElements()
  {
    m_firstFree = 0;
  }

  Removes the first occurrence of the argument from this vector.
If the object is found in this vector, each component in the vector
with an index greater or equal to the object's index is shifted
downward to have an index one smaller than the value it had
previously.
Params: s – Byte to remove from array
Returns: True if the byte was removed, false if it was not found/**
   * Removes the first occurrence of the argument from this vector.
   * If the object is found in this vector, each component in the vector
   * with an index greater or equal to the object's index is shifted
   * downward to have an index one smaller than the value it had
   * previously.
   *
   * @param s Byte to remove from array
   *
   * @return True if the byte was removed, false if it was not found
   */
  private  boolean removeElement(byte s)
  {
    int at=indexOf(s,0);
    if(at<0)
      return false;
    removeElementAt(at);
    return true;
  }

  Deletes the component at the specified index. Each component in
this vector with an index greater or equal to the specified
index is shifted downward to have an index one smaller than
the value it had previously.
Params: at – index of where to remove a byte/**
   * Deletes the component at the specified index. Each component in
   * this vector with an index greater or equal to the specified
   * index is shifted downward to have an index one smaller than
   * the value it had previously.
   *
   * @param at index of where to remove a byte
   */
  private  void removeElementAt(int at)
  {
    // No point in removing elements that "don't exist"...  
    if(at<m_firstFree)
    {
      int index=at/m_blocksize;
      int maxindex=m_firstFree/m_blocksize;
      int offset=at%m_blocksize;
      
      while(index<=maxindex)
      {
        int copylen=m_blocksize-offset-1;
        byte[] block=m_map[index];
        if(null==block)
          block=m_map[index]=new byte[m_blocksize];
        else
          System.arraycopy(block, offset+1, block, offset, copylen);
        if(index<maxindex)
        {
          byte[] next=m_map[index+1];
          if(next!=null)
            block[m_blocksize-1]=(next!=null) ? next[0] : 0;
        }
        else
          block[m_blocksize-1]=0;
        offset=0;
        ++index;
      }
    }
    --m_firstFree;
  }

  Sets the component at the specified index of this vector to be the
specified object. The previous component at that position is discarded.
The index must be a value greater than or equal to 0 and less
than the current size of the vector.
Params: value – 
at –     Index of where to set the object/**
   * Sets the component at the specified index of this vector to be the
   * specified object. The previous component at that position is discarded.
   *
   * The index must be a value greater than or equal to 0 and less
   * than the current size of the vector.
   *
   * @param value
   * @param at     Index of where to set the object
   */
  public void setElementAt(byte value, int at)
  {
    if(at<m_blocksize)
    {
      m_map0[at]=value;
      return;
    }

    int index=at/m_blocksize;
    int offset=at%m_blocksize;
        
    if(index>=m_map.length)
    {
      int newsize=index+m_numblocks;
      byte[][] newMap=new byte[newsize][];
      System.arraycopy(m_map, 0, newMap, 0, m_map.length);
      m_map=newMap;
    }

    byte[] block=m_map[index];
    if(null==block)
      block=m_map[index]=new byte[m_blocksize];
    block[offset]=value;

    if(at>=m_firstFree)
      m_firstFree=at+1;
  }

  Get the nth element. This is often at the innermost loop of an
application, so performance is critical.
Params: i – index of value to get
Throws: ArrayIndexOutOfBoundsException – if the index was _clearly_
unreasonable (negative, or past the highest block).
NullPointerException – if the index points to a block that could
have existed (based on the highest index used) but has never had anything
set into it.
%REVIEW% Could add a catch to create the block in that case, or return 0.
Try/Catch is _supposed_ to be nearly free when not thrown to. Do we
believe that? Should we have a separate safeElementAt?
Returns: value at given index. If that value wasn't previously set,
the result is undefined for performance reasons. It may throw an
exception (see below), may return zero, or (if setSize has previously
been used) may return stale data./**
   * Get the nth element. This is often at the innermost loop of an
   * application, so performance is critical.
   *
   * @param i index of value to get
   *
   * @return value at given index. If that value wasn't previously set,
   * the result is undefined for performance reasons. It may throw an
   * exception (see below), may return zero, or (if setSize has previously
   * been used) may return stale data.
   *
   * @throws ArrayIndexOutOfBoundsException if the index was _clearly_
   * unreasonable (negative, or past the highest block).
   *
   * @throws NullPointerException if the index points to a block that could
   * have existed (based on the highest index used) but has never had anything
   * set into it.
   * %REVIEW% Could add a catch to create the block in that case, or return 0.
   * Try/Catch is _supposed_ to be nearly free when not thrown to. Do we
   * believe that? Should we have a separate safeElementAt?
   */
  public byte elementAt(int i)
  {
    // %OPT% Does this really buy us anything? Test versus division for small,
    // test _plus_ division for big docs.
    if(i<m_blocksize)
      return m_map0[i];

    return m_map[i/m_blocksize][i%m_blocksize];
  }

  Tell if the table contains the given node.
Params: s – object to look for
Returns: true if the object is in the list/**
   * Tell if the table contains the given node.
   *
   * @param s object to look for
   *
   * @return true if the object is in the list
   */
  private  boolean contains(byte s)
  {
    return (indexOf(s,0) >= 0);
  }

  Searches for the first occurence of the given argument,
beginning the search at index, and testing for equality
using the equals method.
Params: elem – object to look for
index – Index of where to begin search
Returns: the index of the first occurrence of the object
argument in this vector at position index or later in the
vector; returns -1 if the object is not found./**
   * Searches for the first occurence of the given argument,
   * beginning the search at index, and testing for equality
   * using the equals method.
   *
   * @param elem object to look for
   * @param index Index of where to begin search
   * @return the index of the first occurrence of the object
   * argument in this vector at position index or later in the
   * vector; returns -1 if the object is not found.
   */
  public int indexOf(byte elem, int index)
  {
    if(index>=m_firstFree)
      return -1;
          
    int bindex=index/m_blocksize;
    int boffset=index%m_blocksize;
    int maxindex=m_firstFree/m_blocksize;
    byte[] block;
    
    for(;bindex<maxindex;++bindex)
    {
      block=m_map[bindex];
      if(block!=null)
        for(int offset=boffset;offset<m_blocksize;++offset)
          if(block[offset]==elem)
            return offset+bindex*m_blocksize;
      boffset=0; // after first
    }
    // Last block may need to stop before end
    int maxoffset=m_firstFree%m_blocksize;
    block=m_map[maxindex];
    for(int offset=boffset;offset<maxoffset;++offset)
      if(block[offset]==elem)
        return offset+maxindex*m_blocksize;

    return -1;    
  }

  Searches for the first occurence of the given argument,
beginning the search at index, and testing for equality
using the equals method.
Params: elem – object to look for
Returns: the index of the first occurrence of the object
argument in this vector at position index or later in the
vector; returns -1 if the object is not found./**
   * Searches for the first occurence of the given argument,
   * beginning the search at index, and testing for equality
   * using the equals method.
   *
   * @param elem object to look for
   * @return the index of the first occurrence of the object
   * argument in this vector at position index or later in the
   * vector; returns -1 if the object is not found.
   */
  public int indexOf(byte elem)
  {
    return indexOf(elem,0);
  }

  Searches for the first occurence of the given argument,
beginning the search at index, and testing for equality
using the equals method.
Params: elem – Object to look for
Returns: the index of the first occurrence of the object
argument in this vector at position index or later in the
vector; returns -1 if the object is not found./**
   * Searches for the first occurence of the given argument,
   * beginning the search at index, and testing for equality
   * using the equals method.
   *
   * @param elem Object to look for
   * @return the index of the first occurrence of the object
   * argument in this vector at position index or later in the
   * vector; returns -1 if the object is not found.
   */
  private  int lastIndexOf(byte elem)
  {
    int boffset=m_firstFree%m_blocksize;
    for(int index=m_firstFree/m_blocksize;
        index>=0;
        --index)
    {
      byte[] block=m_map[index];
      if(block!=null)
        for(int offset=boffset; offset>=0; --offset)
          if(block[offset]==elem)
            return offset+index*m_blocksize;
      boffset=0; // after first
    }
    return -1;
  }

}
Params:	s – Byte to remove from array
Returns:	True if the byte was removed, false if it was not found
Params:	i – index of value to get
Throws:	ArrayIndexOutOfBoundsException – if the index was _clearly_ unreasonable (negative, or past the highest block). NullPointerException – if the index points to a block that could have existed (based on the highest index used) but has never had anything set into it. %REVIEW% Could add a catch to create the block in that case, or return 0. Try/Catch is _supposed_ to be nearly free when not thrown to. Do we believe that? Should we have a separate safeElementAt?
Returns:	value at given index. If that value wasn't previously set, the result is undefined for performance reasons. It may throw an exception (see below), may return zero, or (if setSize has previously been used) may return stale data.
Params:	s – object to look for
Returns:	true if the object is in the list
Params:	elem – object to look for index – Index of where to begin search
Returns:	the index of the first occurrence of the object argument in this vector at position index or later in the vector; returns -1 if the object is not found.
Params:	elem – object to look for
Returns:	the index of the first occurrence of the object argument in this vector at position index or later in the vector; returns -1 if the object is not found.
/

xalan/ serializer/ 2.7.2/ org/apache/xml/utils/SuballocatedByteVector.java
