Package com.tangosol.util.filter

Class EqualsFilter<T,E>

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.util.filter.AbstractQueryRecorderFilter<T>
com.tangosol.util.filter.ExtractorFilter<T,E>
com.tangosol.util.filter.ComparisonFilter<T,E,E>
com.tangosol.util.filter.EqualsFilter<T,E>
Type Parameters:
T - the type of the input argument to the filter
E - the type of the value to use for comparison
All Implemented Interfaces:
ExternalizableLite, PortableObject, Filter<T>, EntryFilter<Object,T>, IndexAwareFilter<Object,T>, QueryRecorderFilter<T>, Serializable
Direct Known Subclasses:
IsNullFilter
public class EqualsFilter<T,E> extends ComparisonFilter<T,E,E> implements IndexAwareFilter<Object,T>
Filter which compares the result of a method invocation with a value for equality.
Author:
cp/gg 2002.10.27
See Also:

  • Constructor Details

    • EqualsFilter

      public EqualsFilter()
      Default constructor (necessary for the ExternalizableLite interface).

    • EqualsFilter

      public EqualsFilter(ValueExtractor<? super T,? extends E> extractor, E value)
      Construct an EqualsFilter for testing equality.
      Parameters:
      extractor - the ValueExtractor to use by this filter
      value - the object to compare the result with

    • EqualsFilter

      public EqualsFilter(String sMethod, E value)
      Construct an EqualsFilter for testing equality.
      Parameters:
      sMethod - the name of the method to invoke via reflection
      value - the object to compare the result with

  • Method Details

    • getOperator

      protected String getOperator()
      Overrides:
      getOperator in class ComparisonFilter<T,E,E>

    • evaluateExtracted

      protected boolean evaluateExtracted(E extracted)
      Evaluate the specified extracted value.
      Specified by:
      evaluateExtracted in class ExtractorFilter<T,E>
      Parameters:
      extracted - an extracted value to evaluate
      Returns:
      true iff the test passes

    • 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 many keys will remain in the set after the index is applied. If no keys will remain in the set after the index is applied, this method should return 0. If all the keys will remain in the set, implying that no entries would be filtered out based on this filter, this method should return setKeys.size(). Otherwise, it should return the value between 0 and setKeys.size(). If there is no index in the specified index map that can be used by this filter, this method should return a negative integer.

      The effectiveness returned will be used by the composite filters to reorder nested filters from most to least effective, in order to optimize query execution.

      Specified by:
      calculateEffectiveness in interface IndexAwareFilter<T,E>
      Overrides:
      calculateEffectiveness in class ExtractorFilter<T,E>
      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(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<T,E>
      Overrides:
      applyIndex in class ExtractorFilter<T,E>
      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