org.apache.xml.utils
Class SuballocatedIntVector

java.lang.Object
  |
  +--org.apache.xml.utils.SuballocatedIntVector

public class SuballocatedIntVector
extends java.lang.Object

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.


Constructor Summary
SuballocatedIntVector()
          Default constructor.
SuballocatedIntVector(int blocksize)
          Construct a IntVector, using the given block size and the default number of blocks (32).
SuballocatedIntVector(int blocksize, int numblocks)
          Construct a IntVector, using the given block size and number of blocks.
 
Method Summary
 void addElement(int value)
          Append a int onto the vector.
 int elementAt(int i)
          Get the nth element.
 int[][] getMap()
          Return the m_map double array
 int[] getMap0()
          Return the internal m_map0 array
 int indexOf(int elem)
          Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
 int indexOf(int elem, int index)
          Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
 void removeAllElements()
          Wipe it out.
 void setElementAt(int value, int at)
          Sets the component at the specified index of this vector to be the specified object.
 void setSize(int sz)
          Set the length of the list.
 int size()
          Get the length of the list.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SuballocatedIntVector

public SuballocatedIntVector()
Default constructor. Note that the default block size is currently 2K, which may be overkill for small lists and undershootng for large ones.

SuballocatedIntVector

public SuballocatedIntVector(int blocksize,
                             int numblocks)
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.
Parameters:
blocksize - Size of block to allocate
numblocks - Number of blocks to allocate

SuballocatedIntVector

public SuballocatedIntVector(int blocksize)
Construct a IntVector, using the given block size and the default number of blocks (32).
Parameters:
blocksize - Size of block to allocate
Method Detail

size

public int size()
Get the length of the list.
Returns:
length of the list

setSize

public void setSize(int sz)
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.
Returns:
length of the list

addElement

public void addElement(int value)
Append a int onto the vector.
Parameters:
value - Int to add to the list

removeAllElements

public void removeAllElements()
Wipe it out. Currently defined as equivalent to setSize(0).

setElementAt

public void setElementAt(int value,
                         int at)
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.
Parameters:
value - object to set
at - Index of where to set the object

elementAt

public int elementAt(int i)
Get the nth element. This is often at the innermost loop of an application, so performance is critical.
Parameters:
i - index of value to get
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.
Throws:
java.lang.ArrayIndexOutOfBoundsException - if the index was _clearly_ unreasonable (negative, or past the highest block).
java.lang.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?

indexOf

public int indexOf(int elem,
                   int index)
Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
Parameters:
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.

indexOf

public int indexOf(int elem)
Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
Parameters:
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.

getMap0

public final int[] getMap0()
Return the internal m_map0 array
Returns:
the m_map0 array

getMap

public final int[][] getMap()
Return the m_map double array
Returns:
the internal map of array of arrays


Copyright 2006 Apache XML Project. All Rights Reserved.