net.sf.swan.xml.input.util
Class ContextMap

java.lang.Object
  |
  +--net.sf.swan.xml.input.util.ContextMap

public final class ContextMap

extends java.lang.Object

Utility for maintaining stacked contexts of key/value mappings. This uses a HashMap-like implementation, but has been optimized for the purpose of maintaining stacked contexts of mappings.

This class is used internally by EventContext components, but is made public here because of its reasonably general utility.

Constructor Summary

ContextMap()

ContextMap(int initialCapacity)

ContextMap(int initialCapacity, float loadFactor)

Method Summary

void	clear() Clear the entries from this map.
java.lang.Object	get(java.lang.Object key)
java.util.Enumeration	keys() Enumerate all of the map's keys.
ContextMap	popContext() Releases this child ContextMap and return its parent.
ContextMap	pushContext() Create a new ContextMap that is a child of this one.
java.lang.Object	put(java.lang.Object key, java.lang.Object value) Add or change an entry.

Methods inherited from class java.lang.Object

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

Constructor Detail

ContextMap

public ContextMap()

ContextMap

public ContextMap(int initialCapacity)

ContextMap

public ContextMap(int initialCapacity,
                  float loadFactor)

Method Detail

get

public java.lang.Object get(java.lang.Object key)

pushContext

public ContextMap pushContext()

Create a new ContextMap that is a child of this one. The new ContextMap will be initialized with the same key/value mappings as this one, but modifications in the child will not be reflected in the parent. This ContextMap will become read-only until all children have been released.

Returns:

the new child ContextMap

popContext

public ContextMap popContext()

Releases this child ContextMap and return its parent.

Returns:

the parent ContextMap of this one

Throws:

java.lang.IllegalStateException - if this ContextMap is not a child of another

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Add or change an entry.

Throws:

java.lang.IllegalStateException - if this ContextMap has child context maps that have not been released.

clear

public void clear()

Clear the entries from this map.

Throws:

java.lang.IllegalStateException - if this ContextMap has child context maps that have not been released.

keys

public java.util.Enumeration keys()

Enumerate all of the map's keys. We return an Enumeration for this rather than an Iterator so that there is no ambiguity about the ability to remove keys (you can't).