Package com.tangosol.util.filter

Class LikeFilter<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,String>
com.tangosol.util.filter.LikeFilter<T,E>
Type Parameters:
T - the type of the input argument to the filter
E - the type of the extracted attribute to use for comparison
All Implemented Interfaces:
ExternalizableLite, PortableObject, Filter<T>, EntryFilter<Object,T>, IndexAwareFilter<Object,T>, QueryRecorderFilter<T>, Serializable
public class LikeFilter<T,E> extends ComparisonFilter<T,E,String> implements IndexAwareFilter<Object,T>
Filter which compares the result of a method invocation with a value for pattern match. A pattern can include regular characters and wildcard characters '_' and '%'.

During pattern matching, regular characters must exactly match the characters in an evaluated string. Wildcard character '_' (underscore) can be matched with any single character, and wildcard character '%' can be matched with any string fragment of zero or more characters.

Author:
cp/gg 2002.10.27
See Also:

  • Constructor Details

    • LikeFilter

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

    • LikeFilter

      public LikeFilter(String sMethod, String sPattern)
      Construct a LikeFilter for pattern match.
      Parameters:
      sMethod - the name of the method to invoke via reflection
      sPattern - the string pattern to compare the result with

    • LikeFilter

      public LikeFilter(String sMethod, String sPattern, boolean fIgnoreCase)
      Construct a LikeFilter for pattern match.
      Parameters:
      sMethod - the name of the method to invoke via reflection
      sPattern - the string pattern to compare the result with
      fIgnoreCase - true to be case-insensitive

    • LikeFilter

      public LikeFilter(String sMethod, String sPattern, char chEscape, boolean fIgnoreCase)
      Construct a LikeFilter for pattern match.
      Parameters:
      sMethod - the name of the method to invoke via reflection
      sPattern - the string pattern to compare the result with
      chEscape - the escape character for escaping '%' and '_'
      fIgnoreCase - true to be case-insensitive

    • LikeFilter

      public LikeFilter(ValueExtractor<? super T,? extends E> extractor, String sPattern)
      Construct a LikeFilter for pattern match.
      Parameters:
      extractor - the ValueExtractor used by this filter
      sPattern - the string pattern to compare the result with

    • LikeFilter

      public LikeFilter(ValueExtractor<? super T,? extends E> extractor, String sPattern, char chEscape, boolean fIgnoreCase)
      Construct a LikeFilter for pattern match.
      Parameters:
      extractor - the ValueExtractor used by this filter
      sPattern - the string pattern to compare the result with
      chEscape - the escape character for escaping '%' and '_'
      fIgnoreCase - true to be case-insensitive

  • Method Details

    • 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 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<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

    • getPattern

      public String getPattern()
      Obtain the filter's pattern string.
      Returns:
      the pattern string

    • isIgnoreCase

      public boolean isIgnoreCase()
      Check whether or not the filter is case incensitive.
      Returns:
      true iff case insensitivity is specifically enabled

    • getEscapeChar

      public char getEscapeChar()
      Obtain the escape character that is used for escaping '%' and '_' in the pattern or zero if there is no escape.
      Returns:
      the escape character

    • showPlan

      public void showPlan()
      Display the execution plan that the LikeFilter has selected.

    • 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
      Overrides:
      readExternal in class ComparisonFilter<T,E,String>
      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
      Overrides:
      writeExternal in class ComparisonFilter<T,E,String>
      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
      Overrides:
      readExternal in class ComparisonFilter<T,E,String>
      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
      Overrides:
      writeExternal in class ComparisonFilter<T,E,String>
      Parameters:
      out - the PofWriter to which to write the object's state
      Throws:
      IOException - if an I/O error occurs

    • buildPlan

      protected void buildPlan()
      Build a plan for processing the LIKE functionality.

    • isMatch

      protected boolean isMatch(String sValue)
      Check the passed String value to see if it matches the pattern that this filter was constructed with.
      Parameters:
      sValue - the String value to match against this filter's pattern
      Returns:
      true iff the passed String value is LIKE this filter's pattern