com.tangosol.util.filter
Class XorFilter

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.util.BitHelper
          com.tangosol.util.ExternalizableHelper
              com.tangosol.util.filter.ArrayFilter
                  com.tangosol.util.filter.XorFilter

All Implemented Interfaces:

ExternalizableLite, PortableObject, Filter, EntryFilter, IndexAwareFilter, java.io.Serializable

public class XorFilter
extends ArrayFilter

Filter which returns the logical exclusive or ("xor") of two other filters.

Author:

cp/gg 2002.10.27

Nested Class Summary

Nested classes/interfaces inherited from class com.tangosol.util.filter.ArrayFilter

ArrayFilter.WeightedFilter

Field Summary

Fields inherited from class com.tangosol.util.filter.ArrayFilter

m_aFilter

Constructor Summary

XorFilter()
Default constructor (necessary for the ExternalizableLite interface).

XorFilter(Filter filterLeft, Filter filterRight)
Construct a "xor" filter.

Method Summary

Filter	applyIndex(java.util.Map mapIndexes, java.util.Set setKeys) Filter remaining keys using a Map of available indexes.
int	calculateEffectiveness(java.util.Map mapIndexes, java.util.Set setKeys) Given a Map of available indexes, determine if this IndexAwareFilter can use any of the indexes to assist in its processing, and if so, determine how effective the use of that index would be.
boolean	evaluate(java.lang.Object o) Apply the test to the object.
boolean	evaluateEntry(java.util.Map.Entry entry) Apply the test to a Map Entry.

Methods inherited from class com.tangosol.util.filter.ArrayFilter

applyFilter, calculateFilters, equals, getFilters, hashCode, readExternal, readExternal, toString, writeExternal, writeExternal

Methods inherited from class com.tangosol.util.BitHelper

countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, toBitString, toBitString, toBitString

Constructor Detail

XorFilter

public XorFilter()

Default constructor (necessary for the ExternalizableLite interface).

XorFilter

public XorFilter(Filter filterLeft,
                 Filter filterRight)

Construct a "xor" filter. The result is defined as:

filterLeft ^ filterRight

Parameters:

filterLeft - the "left" filter

filterRight - the "right" filter

Method Detail

evaluate

public boolean evaluate(java.lang.Object o)

Apply the test to the object.

Parameters:

o - the object to test

Returns:

true if the test passes, false otherwise

evaluateEntry

public boolean evaluateEntry(java.util.Map.Entry entry)

Apply the test to a Map Entry.

Parameters:

entry - the Map Entry to evaluate; never null

Returns:

true if the test passes, false otherwise

calculateEffectiveness

public int calculateEffectiveness(java.util.Map mapIndexes,
                                  java.util.Set setKeys)

Given a Map of available indexes, determine if this IndexAwareFilter can use any of the indexes to assist in its processing, and if so, determine how effective the use of that index would be.

The returned value is an effectiveness estimate of how well this filter can use the specified indexes to filter the specified keys. An operation that requires no more than a single access to the index content (i.e. Equals, NotEquals) has an effectiveness of one. Evaluation of a single entry is assumed to have an effectiveness that depends on the index implementation and is usually measured as a constant number of the single operations. This number is referred to as evaluation cost.

If the effectiveness of a filter evaluates to a number larger than the keySet.size() * <evaluation cost> then a user could avoid using the index and iterate through the keySet calling evaluate rather then applyIndex.

Parameters:

mapIndexes - the available MapIndex objects keyed by the related ValueExtractor; read-only

setKeys - the set of keys that will be filtered; read-only

Returns:

an effectiveness estimate of how well this filter can use the specified indexes to filter the specified keys

applyIndex

public Filter applyIndex(java.util.Map mapIndexes,
                         java.util.Set setKeys)

Filter remaining keys using a Map of available indexes.

The filter is responsible for removing all keys from the passed set of keys that the applicable indexes can prove should be filtered. If the filter does not fully evaluate the remaining keys using just the index information, it must return a filter (which may be an EntryFilter) that can complete the task using an iterating implementation. If, on the other hand, the filter does fully evaluate the remaining keys using just the index information, then it should return null to indicate that no further filtering is necessary.

Parameters:

mapIndexes - the available MapIndex objects keyed by the related ValueExtractor; read-only

setKeys - the mutable set of keys that remain to be filtered

Returns:

a Filter object (which may be an EntryFilter) that can be used to process the remaining keys, or null if no additional filter processing is necessary