Package com.tangosol.util.filter

Class AlwaysFilter<T>

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.AlwaysFilter<T>
Type Parameters:
T - the type of the input argument to the filter
All Implemented Interfaces:
ExternalizableLite, PortableObject, Filter<T>, EntryFilter<Object,T>, IndexAwareFilter<Object,T>, QueryRecorderFilter<T>, Serializable
public class AlwaysFilter<T> extends AbstractQueryRecorderFilter<T> implements EntryFilter<Object,T>, IndexAwareFilter<Object,T>, ExternalizableLite, PortableObject
Filter which always evaluates to true.
Author:
gg 2003.09.18
See Also:

  • Field Details

    • INSTANCE

      public static final AlwaysFilter INSTANCE
      An instance of the AlwaysFilter.

  • Constructor Details

    • AlwaysFilter

      public AlwaysFilter()
      Construct an AlwaysFilter.

  • Method Details

    • evaluate

      public boolean evaluate(T o)
      Apply the test to the input argument.
      Specified by:
      evaluate in interface Filter<T>
      Parameters:
      o - the input argument to evaluate
      Returns:
      true if the input argument matches the filter, otherwise false

    • toExpression

      public String toExpression()
      Description copied from interface: Filter
      Return a string expression for this filter.
      Specified by:
      toExpression in interface Filter<T>
      Returns:
      a string expression for this filter

    • evaluateEntry

      public boolean evaluateEntry(Map.Entry entry)
      Apply the test to a Map Entry.
      Specified by:
      evaluateEntry in interface EntryFilter<Object,T>
      Parameters:
      entry - the Map Entry to evaluate; never null
      Returns:
      true if the test passes, false otherwise

    • 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<Object,T>
      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<Object,T>
      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

    • equals

      public boolean equals(Object o)
      Compare the AlwaysFilter with another object to determine equality.
      Overrides:
      equals in class Object
      Returns:
      true iff this AlwaysFilter and the passed object are equivalent AlwaysFilters

    • hashCode

      public int hashCode()
      Determine a hash value for the AlwaysFilter object according to the general Object.hashCode() contract.
      Overrides:
      hashCode in class Object
      Returns:
      an integer hash value for this AlwaysFilter object

    • toString

      public String toString()
      Return a human-readable description for this Filter.
      Overrides:
      toString in class Object
      Returns:
      a String description of the Filter

    • readExternal

      public void readExternal(DataInput in) throws IOException
      Restore the contents of this object by loading the object's state from the passed DataInput object.
      Specified by:
      readExternal in interface ExternalizableLite
      Parameters:
      in - the DataInput stream to read data from in order to restore the state of this object
      Throws:
      IOException - if an I/O exception occurs

    • writeExternal

      public void writeExternal(DataOutput out) throws IOException
      Save the contents of this object by storing the object's state into the passed DataOutput object.
      Specified by:
      writeExternal in interface ExternalizableLite
      Parameters:
      out - the DataOutput stream to write the state of this object to
      Throws:
      IOException - if an I/O exception occurs

    • readExternal

      public void readExternal(PofReader in) throws IOException
      Restore the contents of a user type instance by reading its state using the specified PofReader object.
      Specified by:
      readExternal in interface PortableObject
      Parameters:
      in - the PofReader from which to read the object's state
      Throws:
      IOException - if an I/O error occurs

    • writeExternal

      public void writeExternal(PofWriter out) throws IOException
      Save the contents of a POF user type instance by writing its state using the specified PofWriter object.
      Specified by:
      writeExternal in interface PortableObject
      Parameters:
      out - the PofWriter to which to write the object's state
      Throws:
      IOException - if an I/O error occurs

    • INSTANCE

      public static <T> AlwaysFilter<T> INSTANCE()
      Return an instance of the AlwaysFilter.
      Type Parameters:
      T - the type of the input argument to the filter
      Returns:
      a AlwaysFilter instance