Oracle® Coherence Java API Reference
v3.5

E14977-01

com.tangosol.util.filter
Class LikeFilter

java.lang.Object
  extended by com.tangosol.util.Base
      extended by com.tangosol.util.BitHelper
          extended by com.tangosol.util.ExternalizableHelper
              extended by com.tangosol.util.filter.ExtractorFilter
                  extended by com.tangosol.util.filter.ComparisonFilter
                      extended by com.tangosol.util.filter.LikeFilter
All Implemented Interfaces:
ExternalizableLite, PortableObject, Filter, EntryFilter, IndexAwareFilter, java.io.Serializable

public class LikeFilter
extends ComparisonFilter
implements IndexAwareFilter

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

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
LikeFilter()
          Default constructor (necessary for the ExternalizableLite interface).
LikeFilter(java.lang.String sMethod, java.lang.String sPattern)
          Construct a LikeFilter for pattern match.
LikeFilter(java.lang.String sMethod, java.lang.String sPattern, boolean fIgnoreCase)
          Construct a LikeFilter for pattern match.
LikeFilter(java.lang.String sMethod, java.lang.String sPattern, char chEscape, boolean fIgnoreCase)
          Construct a LikeFilter for pattern match.
LikeFilter(ValueExtractor extractor, java.lang.String sPattern, char chEscape, boolean fIgnoreCase)
          Construct a LikeFilter for pattern match.
 
Method Summary
 Filter applyIndex(java.util.Map mapIndexes, java.util.Set setKeys)
          Filter remaining keys using a Map of available indexes.
protected  void buildPlan()
          Build a plan for processing the LIKE functionality.
 int calculateEffectiveness(java.util.Map mapIndexes, java.util.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(java.lang.Object oExtracted)
          Evaluate the specified extracted value.
 char getEscapeChar()
          Obtain the escape character that is used for escaping '%' and '_' in the pattern or zero if there is no escape.
 java.lang.String getPattern()
          Obtain the filter's pattern string.
 boolean isIgnoreCase()
          Check whether or not the filter is case incensitive.
protected  boolean isMatch(java.lang.String sValue)
          Check the passed String value to see if it matches the pattern that this filter was constructed with.
 void readExternal(java.io.DataInput in)
          Restore the contents of this object by loading the object's state from the passed DataInput object.
 void readExternal(PofReader in)
          Restore the contents of a user type instance by reading its state using the specified PofReader object.
 void showPlan()
          Display the execution plan that the LikeFilter has selected.
 void writeExternal(java.io.DataOutput out)
          Save the contents of this object by storing the object's state into the passed DataOutput object.
 void writeExternal(PofWriter out)
          Save the contents of a POF user type instance by writing its state using the specified PofWriter object.
 
Methods inherited from class com.tangosol.util.filter.ComparisonFilter
calculateIteratorEffectiveness, calculateMatchEffectiveness, calculateRangeEffectiveness, equals, getValue, hashCode, toString
 
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, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString
 
Methods inherited from interface com.tangosol.util.filter.EntryFilter
evaluateEntry
 
Methods inherited from interface com.tangosol.util.Filter
evaluate
 

Constructor Detail

LikeFilter

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


LikeFilter

public LikeFilter(java.lang.String sMethod,
                  java.lang.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(java.lang.String sMethod,
                  java.lang.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(java.lang.String sMethod,
                  java.lang.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 extractor,
                  java.lang.String sPattern,
                  char chEscape,
                  boolean fIgnoreCase)
Construct a LikeFilter for pattern match.

Parameters:
extractor - the ValueExtractor to use 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 Detail

evaluateExtracted

protected boolean evaluateExtracted(java.lang.Object oExtracted)
Evaluate the specified extracted value.

Specified by:
evaluateExtracted in class ExtractorFilter
Parameters:
oExtracted - an extracted value to evaluate

calculateEffectiveness

public int calculateEffectiveness(java.util.Map mapIndexes,
                                  java.util.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:
an effectiveness estimate of how well this filter can use the specified indexes to filter the specified keys

applyIndex

public Filter applyIndex(java.util.Map mapIndexes,
                         java.util.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

getPattern

public java.lang.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(java.io.DataInput in)
                  throws java.io.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
Parameters:
in - the DataInput stream to read data from in order to restore the state of this object
Throws:
java.io.IOException - if an I/O exception occurs
java.io.NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(java.io.DataOutput out)
                   throws java.io.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
Parameters:
out - the DataOutput stream to write the state of this object to
Throws:
java.io.IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws java.io.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
Parameters:
in - the PofReader from which to read the object's state
Throws:
java.io.IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws java.io.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
Parameters:
out - the PofWriter to which to write the object's state
Throws:
java.io.IOException - if an I/O error occurs

buildPlan

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


isMatch

protected boolean isMatch(java.lang.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

Oracle® Coherence Java API Reference
v3.5

E14977-01

Copyright © 2000, 2009, Oracle. All rights reserved.