Oracle Coherence for C++ API
Release 3.6.1.0

E18813-01

LessEqualsFilter Class Reference

#include <coherence/util/filter/LessEqualsFilter.hpp>

Inherits ComparisonFilter, and IndexAwareFilter.

List of all members.


Detailed Description

Filter which compares the result of a method invocation with a value for "Less or Equals" 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:
djl 2008.03.24

Public Types

typedef spec::Handle  Handle
  LessEqualsFilter Handle definition.
typedef spec::View  View
  LessEqualsFilter View definition.
typedef spec::Holder  Holder
  LessEqualsFilter Holder definition.

Public Member Functions

virtual size32_t  calculateEffectiveness (Map::View vMapIndexes, Set::View vSetKeys) const
  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:
vMapIndexes  the available MapIndex objects keyed by the related ValueExtractor; read-only
vSetKeys  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

virtual Filter::View  applyIndex (Map::View vMapIndexes, Set::Handle hSetKeys) const
  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:
vMapIndexes  the available MapIndex objects keyed by the related ValueExtractor; read-only
hSetKeys  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


Protected Member Functions

  LessEqualsFilter ()
  Default constructor (necessary for the PortableObject interface).
  LessEqualsFilter (ValueExtractor::View vValueExtractor, Comparable::View vComparable)
  Construct a LessEqualsFilter for testing "Less or Equals" condition.
virtual bool  evaluateExtracted (Object::View vExtracted) const
  Evaluate the specified extracted value.
Parameters:
vExtracted  an extracted value to evaluate


Constructor & Destructor Documentation

LessEqualsFilter ( ValueExtractor::View  vValueExtractor,
Comparable::View  vComparable  
) [protected]

Construct a LessEqualsFilter for testing "Less or Equals" condition.

Parameters:
vValueExtractor  the ValueExtractor to use by this filter
vComparable  the object to compare the result with

The documentation for this class was generated from the following file:
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