| /* |
| * 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: SuballocatedIntVector.java 468655 2006-10-28 07:12:06Z minchau $ |
| */ |
| package org.apache.xml.utils; |
| |
| /** |
| * A very simple table that stores a list of int. 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. |
| * |
| * Retrieval performance is critical, since this is used at the core |
| * of the DTM model. (Append performance is almost as important.) |
| * That's pushing me toward just letting reads from unset indices |
| * throw exceptions or return stale data; safer behavior would have |
| * performance costs. |
| * */ |
| public class SuballocatedIntVector |
| { |
| /** Size of blocks to allocate */ |
| protected int m_blocksize; |
| |
| /** Bitwise addressing (much faster than div/remainder */ |
| protected int m_SHIFT, m_MASK; |
| |
| /** The default number of blocks to (over)allocate by */ |
| protected static final int NUMBLOCKS_DEFAULT = 32; |
| |
| /** The number of blocks to (over)allocate by */ |
| protected int m_numblocks = NUMBLOCKS_DEFAULT; |
| |
| /** Array of arrays of ints */ |
| protected int m_map[][]; |
| |
| /** Number of ints in array */ |
| protected int m_firstFree = 0; |
| |
| /** "Shortcut" handle to m_map[0]. Surprisingly helpful for short vectors. */ |
| protected int m_map0[]; |
| |
| /** "Shortcut" handle to most recently added row of m_map. |
| * Very helpful during construction. |
| * @xsl.usage internal |
| */ |
| protected int m_buildCache[]; |
| protected int m_buildCacheStartIndex; |
| |
| |
| /** |
| * Default constructor. Note that the default |
| * block size is currently 2K, which may be overkill for |
| * small lists and undershootng for large ones. |
| */ |
| public SuballocatedIntVector() |
| { |
| this(2048); |
| } |
| |
| /** |
| * Construct a IntVector, using the given block size and number |
| * of blocks. For efficiency, we will round the requested size |
| * off to a power of two. |
| * |
| * @param blocksize Size of block to allocate |
| * @param numblocks Number of blocks to allocate |
| * */ |
| public SuballocatedIntVector(int blocksize, int numblocks) |
| { |
| //m_blocksize = blocksize; |
| for(m_SHIFT=0;0!=(blocksize>>>=1);++m_SHIFT) |
| ; |
| m_blocksize=1<<m_SHIFT; |
| m_MASK=m_blocksize-1; |
| m_numblocks = numblocks; |
| |
| m_map0=new int[m_blocksize]; |
| m_map = new int[numblocks][]; |
| m_map[0]=m_map0; |
| m_buildCache = m_map0; |
| m_buildCacheStartIndex = 0; |
| } |
| |
| /** Construct a IntVector, using the given block size and |
| * the default number of blocks (32). |
| * |
| * @param blocksize Size of block to allocate |
| * */ |
| public SuballocatedIntVector(int blocksize) |
| { |
| this(blocksize, NUMBLOCKS_DEFAULT); |
| } |
| |
| /** |
| * Get the length of the list. |
| * |
| * @return length of the list |
| */ |
| public int size() |
| { |
| return m_firstFree; |
| } |
| |
| /** |
| * Set the length of the list. This will only work to truncate the list, and |
| * even then it has not been heavily tested and may not be trustworthy. |
| * |
| * @return length of the list |
| */ |
| public void setSize(int sz) |
| { |
| if(m_firstFree>sz) // Whups; had that backward! |
| m_firstFree = sz; |
| } |
| |
| /** |
| * Append a int onto the vector. |
| * |
| * @param value Int to add to the list |
| */ |
| public void addElement(int value) |
| { |
| int indexRelativeToCache = m_firstFree - m_buildCacheStartIndex; |
| |
| // Is the new index an index into the cache row of m_map? |
| if(indexRelativeToCache >= 0 && indexRelativeToCache < m_blocksize) { |
| m_buildCache[indexRelativeToCache]=value; |
| ++m_firstFree; |
| } else { |
| // Growing the outer array should be rare. We initialize to a |
| // total of m_blocksize squared elements, which at the default |
| // size is 4M integers... and we grow by at least that much each |
| // time. However, attempts to microoptimize for this (assume |
| // long enough and catch exceptions) yield no noticable |
| // improvement. |
| |
| int index=m_firstFree>>>m_SHIFT; |
| int offset=m_firstFree&m_MASK; |
| |
| if(index>=m_map.length) |
| { |
| int newsize=index+m_numblocks; |
| int[][] newMap=new int[newsize][]; |
| System.arraycopy(m_map, 0, newMap, 0, m_map.length); |
| m_map=newMap; |
| } |
| int[] block=m_map[index]; |
| if(null==block) |
| block=m_map[index]=new int[m_blocksize]; |
| block[offset]=value; |
| |
| // Cache the current row of m_map. Next m_blocksize-1 |
| // values added will go to this row. |
| m_buildCache = block; |
| m_buildCacheStartIndex = m_firstFree-offset; |
| |
| ++m_firstFree; |
| } |
| } |
| |
| /** |
| * Append several int values onto the vector. |
| * |
| * @param value Int to add to the list |
| */ |
| private void addElements(int 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_SHIFT; |
| int offset=m_firstFree&m_MASK; |
| m_firstFree+=numberOfElements; |
| while( numberOfElements>0) |
| { |
| if(index>=m_map.length) |
| { |
| int newsize=index+m_numblocks; |
| int[][] newMap=new int[newsize][]; |
| System.arraycopy(m_map, 0, newMap, 0, m_map.length); |
| m_map=newMap; |
| } |
| int[] block=m_map[index]; |
| if(null==block) |
| block=m_map[index]=new int[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 numberOfElements Int to add to the list |
| */ |
| private void addElements(int numberOfElements) |
| { |
| int newlen=m_firstFree+numberOfElements; |
| if(newlen>m_blocksize) |
| { |
| int index=m_firstFree>>>m_SHIFT; |
| int newindex=(m_firstFree+numberOfElements)>>>m_SHIFT; |
| for(int i=index+1;i<=newindex;++i) |
| m_map[i]=new int[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 Int to insert |
| * @param at Index of where to insert |
| */ |
| private void insertElementAt(int value, int at) |
| { |
| if(at==m_firstFree) |
| addElement(value); |
| else if (at>m_firstFree) |
| { |
| int index=at>>>m_SHIFT; |
| if(index>=m_map.length) |
| { |
| int newsize=index+m_numblocks; |
| int[][] newMap=new int[newsize][]; |
| System.arraycopy(m_map, 0, newMap, 0, m_map.length); |
| m_map=newMap; |
| } |
| int[] block=m_map[index]; |
| if(null==block) |
| block=m_map[index]=new int[m_blocksize]; |
| int offset=at&m_MASK; |
| block[offset]=value; |
| m_firstFree=offset+1; |
| } |
| else |
| { |
| int index=at>>>m_SHIFT; |
| int maxindex=m_firstFree>>>m_SHIFT; // %REVIEW% (m_firstFree+1?) |
| ++m_firstFree; |
| int offset=at&m_MASK; |
| int push; |
| |
| // ***** Easier to work down from top? |
| while(index<=maxindex) |
| { |
| int copylen=m_blocksize-offset-1; |
| int[] block=m_map[index]; |
| if(null==block) |
| { |
| push=0; |
| block=m_map[index]=new int[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. Currently defined as equivalent to setSize(0). |
| */ |
| public void removeAllElements() |
| { |
| m_firstFree = 0; |
| m_buildCache = m_map0; |
| m_buildCacheStartIndex = 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 Int to remove from array |
| * |
| * @return True if the int was removed, false if it was not found |
| */ |
| private boolean removeElement(int 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 i index of where to remove and int |
| */ |
| private void removeElementAt(int at) |
| { |
| // No point in removing elements that "don't exist"... |
| if(at<m_firstFree) |
| { |
| int index=at>>>m_SHIFT; |
| int maxindex=m_firstFree>>>m_SHIFT; |
| int offset=at&m_MASK; |
| |
| while(index<=maxindex) |
| { |
| int copylen=m_blocksize-offset-1; |
| int[] block=m_map[index]; |
| if(null==block) |
| block=m_map[index]=new int[m_blocksize]; |
| else |
| System.arraycopy(block, offset+1, block, offset, copylen); |
| if(index<maxindex) |
| { |
| int[] 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 value object to set |
| * @param at Index of where to set the object |
| */ |
| public void setElementAt(int value, int at) |
| { |
| if(at<m_blocksize) |
| m_map0[at]=value; |
| else |
| { |
| int index=at>>>m_SHIFT; |
| int offset=at&m_MASK; |
| |
| if(index>=m_map.length) |
| { |
| int newsize=index+m_numblocks; |
| int[][] newMap=new int[newsize][]; |
| System.arraycopy(m_map, 0, newMap, 0, m_map.length); |
| m_map=newMap; |
| } |
| |
| int[] block=m_map[index]; |
| if(null==block) |
| block=m_map[index]=new int[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. |
| * |
| * @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 int elementAt(int i) |
| { |
| // This is actually a significant optimization! |
| if(i<m_blocksize) |
| return m_map0[i]; |
| |
| return m_map[i>>>m_SHIFT][i&m_MASK]; |
| } |
| |
| /** |
| * 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(int 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(int elem, int index) |
| { |
| if(index>=m_firstFree) |
| return -1; |
| |
| int bindex=index>>>m_SHIFT; |
| int boffset=index&m_MASK; |
| int maxindex=m_firstFree>>>m_SHIFT; |
| int[] 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_MASK; |
| 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(int 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(int elem) |
| { |
| int boffset=m_firstFree&m_MASK; |
| for(int index=m_firstFree>>>m_SHIFT; |
| index>=0; |
| --index) |
| { |
| int[] 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; |
| } |
| |
| /** |
| * Return the internal m_map0 array |
| * @return the m_map0 array |
| */ |
| public final int[] getMap0() |
| { |
| return m_map0; |
| } |
| |
| /** |
| * Return the m_map double array |
| * @return the internal map of array of arrays |
| */ |
| public final int[][] getMap() |
| { |
| return m_map; |
| } |
| |
| } |