weblogic.apache.xml.utils
Class SuballocatedIntVector

java.lang.Object
  |
  +--weblogic.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.

This class is based on an implementation from the Apache XML Project. In future releases the XML parser, XSLT processor, and associated classes will likely be updated to be based on a later version of the Apache implementations. Since Apache does not guarantee backwards compatibility between versions of their software, we cannot guarantee backwards compatibility of any of the classes contained in the weblogic.apache package or sub-packages.

Field Summary

protected int	m_blocksize Size of blocks to allocate
protected int	m_firstFree Number of ints in array
protected int[][]	m_map Array of arrays of ints
protected int[]	m_map0 "Shortcut" handle to m_map[0].
protected int	m_MASK Bitwise addressing (much faster than div/remainder
protected int	m_numblocks Number of blocks to (over)allocate by
protected int	m_SHIFT Bitwise addressing (much faster than div/remainder

Constructor Summary

SuballocatedIntVector()
Default constructor.

SuballocatedIntVector(int blocksize)
Construct a IntVector, using the given block size.

SuballocatedIntVector(int blocksize, int increasesize)
Deprecated. use SuballocatedIntVector(int)

Method Summary

void	addElement(int value) Append a int onto the vector.
int	elementAt(int i) Get the nth element.
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.
int	size() Get the length of the list.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_blocksize

protected int m_blocksize

Size of blocks to allocate

m_SHIFT

protected int m_SHIFT

Bitwise addressing (much faster than div/remainder

m_MASK

protected int m_MASK

Bitwise addressing (much faster than div/remainder

m_numblocks

protected int m_numblocks

Number of blocks to (over)allocate by

m_map

protected int[][] m_map

Array of arrays of ints

m_firstFree

protected int m_firstFree

Number of ints in array

m_map0

protected int[] m_map0

"Shortcut" handle to m_map[0]. Surprisingly helpful for short vectors.

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)

Construct a IntVector, using the given block size. For efficiency, we will round the requested size off to a power of two.

Parameters:

blocksize - Size of block to allocate

SuballocatedIntVector

public SuballocatedIntVector(int blocksize,
                             int increasesize)

Deprecated. use SuballocatedIntVector(int)

We never _did_ use the increasesize parameter, so I'm phasing this constructor out.

See Also:

SuballocatedIntVector(int)

Method Detail

size

public int size()

Get the length of the list.

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:

node - object to set

index - 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.

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.