com.tangosol.util.filter
Class GreaterFilter

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.util.BitHelper
          com.tangosol.util.ExternalizableHelper
              com.tangosol.util.filter.ExtractorFilter
                  com.tangosol.util.filter.ComparisonFilter
                      com.tangosol.util.filter.GreaterFilter

All Implemented Interfaces:

ExternalizableLite, PortableObject, Filter, EntryFilter, IndexAwareFilter, Serializable

public class GreaterFilter
extends ComparisonFilter
implements IndexAwareFilter

Filter which compares the result of a method invocation with a value for "Greater" condition. In a case when either result of a method invocation or a value to compare are equal to null, the evaluate test yields false. This approach is equivalent to the way the NULL values are handled by SQL.

Author:

cp/gg 2002.10.29

Field Summary

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

m_oValue

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

EVAL_COST, m_extractor

Constructor Summary

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

GreaterFilter(String sMethod, Comparable oValue)
Construct a GreaterFilter for testing "Greater" condition.

GreaterFilter(String sMethod, double dValue)
Construct a GreaterFilter for testing "Greater" condition.

GreaterFilter(String sMethod, float fValue)
Construct a GreaterFilter for testing "Greater" condition.

GreaterFilter(String sMethod, int iValue)
Construct a GreaterFilter for testing "Greater" condition.

GreaterFilter(String sMethod, long lValue)
Construct a GreaterFilter for testing "Greater" condition.

GreaterFilter(ValueExtractor extractor, Comparable oValue)
Construct a GreaterFilter for testing "Greater" condition.

Method Summary

Filter	applyIndex(Map mapIndexes, Set setKeys) Filter remaining keys using a Map of available indexes.
int	calculateEffectiveness(Map mapIndexes, 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.
protected boolean	evaluateExtracted(Object oExtracted) Evaluate the specified extracted value.

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

equals, getValue, hashCode, readExternal, readExternal, toString, writeExternal, writeExternal

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

evaluate, evaluateEntry, extract, getValueExtractor

Methods inherited from class com.tangosol.util.BitHelper

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

Methods inherited from interface com.tangosol.util.filter.EntryFilter

evaluateEntry

Methods inherited from interface com.tangosol.util.Filter

evaluate

Constructor Detail

GreaterFilter

public GreaterFilter()

Default constructor (necessary for the ExternalizableLite interface).

GreaterFilter

public GreaterFilter(ValueExtractor extractor,
                     Comparable oValue)

Construct a GreaterFilter for testing "Greater" condition.

Parameters:

extractor - the ValueExtractor to use by this filter

oValue - the object to compare the result with

GreaterFilter

public GreaterFilter(String sMethod,
                     Comparable oValue)

Construct a GreaterFilter for testing "Greater" condition.

Parameters:

sMethod - the name of the method to invoke via reflection

oValue - the object to compare the result with

GreaterFilter

public GreaterFilter(String sMethod,
                     int iValue)

Construct a GreaterFilter for testing "Greater" condition.

Parameters:

sMethod - the name of the method to invoke via reflection

iValue - the integer value to compare the result with

GreaterFilter

public GreaterFilter(String sMethod,
                     long lValue)

Construct a GreaterFilter for testing "Greater" condition.

Parameters:

sMethod - the name of the method to invoke via reflection

lValue - the long value to compare the result with

GreaterFilter

public GreaterFilter(String sMethod,
                     float fValue)

Construct a GreaterFilter for testing "Greater" condition.

Parameters:

sMethod - the name of the method to invoke via reflection

fValue - the float value to compare the result with

GreaterFilter

public GreaterFilter(String sMethod,
                     double dValue)

Construct a GreaterFilter for testing "Greater" condition.

Parameters:

sMethod - the name of the method to invoke via reflection

dValue - the double value to compare the result with

Method Detail

evaluateExtracted

protected boolean evaluateExtracted(Object oExtracted)

Evaluate the specified extracted value.

Specified by:

evaluateExtracted in class ExtractorFilter

Parameters:

oExtracted - an extracted value to evaluate

calculateEffectiveness

public int calculateEffectiveness(Map mapIndexes,
                                  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.

Specified by:

calculateEffectiveness in interface IndexAwareFilter

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:

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

applyIndex

public Filter applyIndex(Map mapIndexes,
                         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.

Specified by:

applyIndex in interface IndexAwareFilter

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