Oracle Coherence for C++ API
Release 3.6.1.0

E18813-01

LikeFilter Class Reference

#include <coherence/util/filter/LikeFilter.hpp>

Inherits ComparisonFilter, and IndexAwareFilter.

List of all members.


Detailed Description

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:
djl 2008.07.24

Public Types

typedef spec::Handle  Handle
  LikeFilter Handle definition.
typedef spec::View  View
  LikeFilter View definition.
typedef spec::Holder  Holder
  LikeFilter Holder definition.

Public Member Functions

virtual size32_t  calculateEffectiveness (Map::View vMapIndexes, Set::View vSetKeys) const
  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.

Parameters:
vMapIndexes  the available MapIndex objects keyed by the related ValueExtractor; read-only
vSetKeys  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

virtual Filter::View  applyIndex (Map::View vMapIndexes, Set::Handle hSetKeys) const
  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.

Parameters:
vMapIndexes  the available MapIndex objects keyed by the related ValueExtractor; read-only
hSetKeys  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

virtual void  readExternal (PofReader::Handle hIn)
 
virtual void  writeExternal (PofWriter::Handle hOut) const
 
virtual String::View  getPattern () const
  Obtain the filter's pattern string.
virtual bool  isIgnoreCase () const
  Check whether or not the filter is case incensitive.
virtual char16_t  getEscapeChar () const
  Obtain the escape character that is used for escaping '' and '_' in the pattern or zero if there is no escape.
virtual void  showPlan (std::ostream &out) const
  Display the execution plan that the LikeFilter has selected.

Protected Member Functions

  LikeFilter ()
  Default constructor (necessary for the PortableObject interface).
  LikeFilter (ValueExtractor::View vExtractor, String::View vsPattern, char16_t chEscape=(char16_t) 0, bool fIgnoreCase=false)
  Construct a LikeFilter for pattern match.
virtual bool  evaluateExtracted (Object::View vExtracted) const
  Evaluate the specified extracted value.
Parameters:
vExtracted  an extracted value to evaluate

virtual void  buildPlan ()
  Build a plan for processing the LIKE functionality.
virtual bool  isMatch (String::View vsValue) const
  Check the passed String value to see if it matches the pattern that this filter was constructed with.

Constructor & Destructor Documentation

LikeFilter ( ValueExtractor::View  vExtractor,
String::View  vsPattern,
char16_t  chEscape = (char16_t) 0,
bool  fIgnoreCase = false  
) [protected]

Construct a LikeFilter for pattern match.

Parameters:
vExtractor  the ValueExtractor to use by this filter
vsPattern  the string pattern to compare the result with
chEscape  the escape character for escaping '' and '_'
fIgnoreCase  true to be case-insensitive

Member Function Documentation

virtual String::View getPattern (  )  const [virtual]

Obtain the filter's pattern string.

Returns:
the pattern string

virtual bool isIgnoreCase (  )  const [virtual]

Check whether or not the filter is case incensitive.

Returns:
true iff case insensitivity is specifically enabled

virtual char16_t getEscapeChar (  )  const [virtual]

Obtain the escape character that is used for escaping '' and '_' in the pattern or zero if there is no escape.

Returns:
the escape character

virtual void showPlan ( std::ostream &  out  )  const [virtual]

Display the execution plan that the LikeFilter has selected.

Parameters:
out  the ostream to display the plan on

virtual bool isMatch ( String::View  vsValue  )  const [protected, virtual]

Check the passed String value to see if it matches the pattern that this filter was constructed with.

Parameters:
vsValue  the String value to match against this filter's pattern
Returns:
true iff the passed String value is LIKE this filter's pattern

The documentation for this class was generated from the following file:
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