com.tangosol.util.filter
Class LikeFilter

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.util.BitHelper
          com.tangosol.util.ExternalizableHelper
              com.tangosol.util.filter.ExtractorFilter
                  com.tangosol.util.filter.ComparisonFilter
                      com.tangosol.util.filter.LikeFilter

All Implemented Interfaces:

ExternalizableLite, PortableObject, Filter, EntryFilter, IndexAwareFilter, 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(String sMethod, String sPattern)
Construct a LikeFilter for pattern match.

LikeFilter(String sMethod, String sPattern, boolean fIgnoreCase)
Construct a LikeFilter for pattern match.

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

LikeFilter(ValueExtractor extractor, String sPattern, char chEscape, boolean fIgnoreCase)
Construct a LikeFilter for pattern match.

Method Summary

Filter	applyIndex(Map mapIndexes, Set setKeys) Filter remaining keys using a Map of available indexes.
protected void	buildPlan() Build a plan for processing the LIKE functionality.
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.
protected boolean	evaluateExtracted(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.
String	getPattern() Obtain the filter's pattern string.
boolean	isIgnoreCase() Check whether or not the filter is case incensitive.
protected boolean	isMatch(String sValue) Check the passed String value to see if it matches the pattern that this filter was constructed with.
void	readExternal(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(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

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, 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(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 extractor,
                  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(Object oExtracted)

Evaluate the specified extracted value.

Specified by:

evaluateExtracted in class ExtractorFilter

Parameters:

oExtracted - an extracted value to evaluate

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

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:

a 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

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

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

NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

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

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

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

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