- /*
- * Copyright 1999-2004 The Apache Software Foundation.
- *
- * Licensed 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,v 1.6 2004/02/17 04:21:14 minchau Exp $
- */
- package com.sun.org.apache.xml.internal.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
- */
- public class SuballocatedByteVector
- {
- /** Size of blocks to allocate */
- protected int m_blocksize;
-
- /** Number of blocks to (over)allocate by */
- protected int m_numblocks=32;
-
- /** Array of arrays of bytes */
- protected byte m_map[][];
-
- /** Number of bytes in array */
- protected int m_firstFree = 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.
- */
- public SuballocatedByteVector()
- {
- this(2048);
- }
-
- /**
- * 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.
- *
- * @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.
- *
- * @return length of the list
- */
- public int size()
- {
- return m_firstFree;
- }
-
- /**
- * 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.
- *
- * @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_firstFreem_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.
- *
- * @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_firstFreem_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.
- *
- * @param value Byte to add to the list
- */
- 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!
- *
- * @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=atm_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=atm_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.
- */
- 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.
- *
- * @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.
- *
- * @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=atm_blocksize;
- int maxindex=m_firstFreem_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.
- *
- * @param node object to set
- * @param index 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=atm_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.
- *
- * @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.
- *
- * @throw ArrayIndexOutOfBoundsException if the index was _clearly_
- * unreasonable (negative, or past the highest block).
- *
- * @throw 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[im_blocksize][i%m_blocksize];
- }
-
- /**
- * 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.
- *
- * @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=indexm_blocksize;
- int boffset=index%m_blocksize;
- int maxindex=m_firstFreem_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.
- *
- * @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.
- *
- * @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_firstFreem_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;
- }
-
- }