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Public Member Functions | Static Public Member Functions | Static Public Attributes | Protected Member Functions | Protected Attributes
Lucene::FuzzyQuery Class Reference

Implements the fuzzy search query. The similarity measurement is based on the Levenshtein (edit distance) algorithm. More...

#include <FuzzyQuery.h>

+ Inheritance diagram for Lucene::FuzzyQuery:

Public Member Functions

 FuzzyQuery (const TermPtr &term, double minimumSimilarity, int32_t prefixLength)
 Create a new FuzzyQuery that will match terms with a similarity of at least minimumSimilarity to term. If a prefixLength > 0 is specified, a common prefix of that length is also required.
 
 FuzzyQuery (const TermPtr &term, double minimumSimilarity)
 
 FuzzyQuery (const TermPtr &term)
 
virtual ~FuzzyQuery ()
 
virtual String getClassName ()
 
boost::shared_ptr< FuzzyQueryshared_from_this ()
 
double getMinSimilarity ()
 Returns the minimum similarity that is required for this query to match.
 
int32_t getPrefixLength ()
 Returns the non-fuzzy prefix length. This is the number of characters at the start of a term that must be identical (not fuzzy) to the query term if the query is to match that term.
 
TermPtr getTerm ()
 Returns the pattern term.
 
virtual void setRewriteMethod (const RewriteMethodPtr &method)
 Sets the rewrite method to be used when executing the query. You can use one of the four core methods, or implement your own subclass of RewriteMethod.
 
virtual QueryPtr rewrite (const IndexReaderPtr &reader)
 Called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.
 
virtual LuceneObjectPtr clone (const LuceneObjectPtr &other=LuceneObjectPtr())
 Returns a clone of this query.
 
virtual String toString (const String &field)
 Prints a query to a string, with field assumed to be the default field and omitted.
 
virtual int32_t hashCode ()
 Return hash code for this object.
 
virtual bool equals (const LuceneObjectPtr &other)
 Return whether two objects are equal.
 
- Public Member Functions inherited from Lucene::MultiTermQuery
 MultiTermQuery ()
 
virtual ~MultiTermQuery ()
 
boost::shared_ptr< MultiTermQueryshared_from_this ()
 
int32_t getTotalNumberOfTerms ()
 Return the number of unique terms visited during execution of the query. If there are many of them, you may consider using another query type or optimize your total term count in index.
 
void clearTotalNumberOfTerms ()
 Resets the counting of unique terms. Do this before executing the query/filter.
 
virtual RewriteMethodPtr getRewriteMethod ()
 
- Public Member Functions inherited from Lucene::Query
 Query ()
 
virtual ~Query ()
 
boost::shared_ptr< Queryshared_from_this ()
 
virtual void setBoost (double b)
 Sets the boost for this query clause to b. Documents matching this clause will (in addition to the normal weightings) have their score multiplied by b.
 
virtual double getBoost ()
 Gets the boost for this clause. Documents matching this clause will (in addition to the normal weightings) have their score multiplied by b. The boost is 1.0 by default.
 
virtual String toString ()
 Prints a query to a string.
 
virtual WeightPtr createWeight (const SearcherPtr &searcher)
 Constructs an appropriate Weight implementation for this query. Only implemented by primitive queries, which re-write to themselves.
 
virtual WeightPtr weight (const SearcherPtr &searcher)
 Constructs and initializes a Weight for a top-level query.
 
virtual QueryPtr combine (Collection< QueryPtr > queries)
 Called when re-writing queries under MultiSearcher.
 
virtual void extractTerms (SetTerm terms)
 Adds all terms occurring in this query to the terms set. Only works if this query is in its rewritten form.
 
virtual SimilarityPtr getSimilarity (const SearcherPtr &searcher)
 Returns the Similarity implementation to be used for this query. Subclasses may override this method to specify their own Similarity implementation, perhaps one that delegates through that of the Searcher. By default the Searcher's Similarity implementation is returned.
 
String boostString ()
 Return given boost value as a string.
 
- Public Member Functions inherited from Lucene::LuceneObject
virtual ~LuceneObject ()
 
virtual void initialize ()
 Called directly after instantiation to create objects that depend on this object being fully constructed.
 
virtual int32_t compareTo (const LuceneObjectPtr &other)
 Compare two objects.
 
- Public Member Functions inherited from Lucene::LuceneSync
virtual ~LuceneSync ()
 
virtual SynchronizePtr getSync ()
 Return this object synchronize lock.
 
virtual LuceneSignalPtr getSignal ()
 Return this object signal.
 
virtual void lock (int32_t timeout=0)
 Lock this object using an optional timeout.
 
virtual void unlock ()
 Unlock this object.
 
virtual bool holdsLock ()
 Returns true if this object is currently locked by current thread.
 
virtual void wait (int32_t timeout=0)
 Wait for signal using an optional timeout.
 
virtual void notifyAll ()
 Notify all threads waiting for signal.
 

Static Public Member Functions

static String _getClassName ()
 
static double defaultMinSimilarity ()
 
- Static Public Member Functions inherited from Lucene::MultiTermQuery
static String _getClassName ()
 
static RewriteMethodPtr CONSTANT_SCORE_FILTER_REWRITE ()
 A rewrite method that first creates a private Filter, by visiting each term in sequence and marking all docs for that term. Matching documents are assigned a constant score equal to the query's boost.
 
static RewriteMethodPtr SCORING_BOOLEAN_QUERY_REWRITE ()
 A rewrite method that first translates each term into BooleanClause.Occur#SHOULD clause in a BooleanQuery, and keeps the scores as computed by the query. Note that typically such scores are meaningless to the user, and require non-trivial CPU to compute, so it's almost always better to use CONSTANT_SCORE_AUTO_REWRITE_DEFAULT instead.
 
static RewriteMethodPtr CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE ()
 Like SCORING_BOOLEAN_QUERY_REWRITE except scores are not computed. Instead, each matching document receives a constant score equal to the query's boost.
 
static RewriteMethodPtr CONSTANT_SCORE_AUTO_REWRITE_DEFAULT ()
 Read-only default instance of ConstantScoreAutoRewrite, with ConstantScoreAutoRewrite#setTermCountCutoff set to ConstantScoreAutoRewrite#DEFAULT_TERM_COUNT_CUTOFF and ConstantScoreAutoRewrite#setDocCountPercent set to ConstantScoreAutoRewrite#DEFAULT_DOC_COUNT_PERCENT. Note that you cannot alter the configuration of this instance; you'll need to create a private instance instead.
 
- Static Public Member Functions inherited from Lucene::Query
static String _getClassName ()
 
static QueryPtr mergeBooleanQueries (Collection< BooleanQueryPtr > queries)
 Merges the clauses of a set of BooleanQuery's into a single BooleanQuery.
 

Static Public Attributes

static const int32_t defaultPrefixLength
 

Protected Member Functions

void ConstructQuery (const TermPtr &term, double minimumSimilarity, int32_t prefixLength)
 
virtual FilteredTermEnumPtr getEnum (const IndexReaderPtr &reader)
 Construct the enumeration to be used, expanding the pattern term.
 
- Protected Member Functions inherited from Lucene::MultiTermQuery
void incTotalNumberOfTerms (int32_t inc)
 
- Protected Member Functions inherited from Lucene::LuceneObject
 LuceneObject ()
 

Protected Attributes

double minimumSimilarity
 
int32_t prefixLength
 
bool termLongEnough
 
TermPtr term
 
- Protected Attributes inherited from Lucene::MultiTermQuery
RewriteMethodPtr rewriteMethod
 
int32_t numberOfTerms
 
- Protected Attributes inherited from Lucene::Query
double boost
 
- Protected Attributes inherited from Lucene::LuceneSync
SynchronizePtr objectLock
 
LuceneSignalPtr objectSignal
 

Detailed Description

Implements the fuzzy search query. The similarity measurement is based on the Levenshtein (edit distance) algorithm.

Warning: this query is not very scalable with its default prefix length of 0 - in this case, every term will be enumerated and cause an edit score calculation.

Constructor & Destructor Documentation

◆ FuzzyQuery() [1/3]

Lucene::FuzzyQuery::FuzzyQuery ( const TermPtr term,
double  minimumSimilarity,
int32_t  prefixLength 
)

Create a new FuzzyQuery that will match terms with a similarity of at least minimumSimilarity to term. If a prefixLength > 0 is specified, a common prefix of that length is also required.

Parameters
termThe term to search for
minimumSimilarityA value between 0 and 1 to set the required similarity between the query term and the matching terms. For example, for a minimumSimilarity of 0.5 a term of the same length as the query term is considered similar to the query term if the edit distance between both terms is less than length(term) * 0.5
prefixLengthLength of common (non-fuzzy) prefix

◆ FuzzyQuery() [2/3]

Lucene::FuzzyQuery::FuzzyQuery ( const TermPtr term,
double  minimumSimilarity 
)

◆ FuzzyQuery() [3/3]

Lucene::FuzzyQuery::FuzzyQuery ( const TermPtr term)

◆ ~FuzzyQuery()

virtual Lucene::FuzzyQuery::~FuzzyQuery ( )
virtual

Member Function Documentation

◆ _getClassName()

static String Lucene::FuzzyQuery::_getClassName ( )
inlinestatic

◆ clone()

virtual LuceneObjectPtr Lucene::FuzzyQuery::clone ( const LuceneObjectPtr other = LuceneObjectPtr())
virtual

Returns a clone of this query.

Reimplemented from Lucene::MultiTermQuery.

◆ ConstructQuery()

void Lucene::FuzzyQuery::ConstructQuery ( const TermPtr term,
double  minimumSimilarity,
int32_t  prefixLength 
)
protected

◆ defaultMinSimilarity()

static double Lucene::FuzzyQuery::defaultMinSimilarity ( )
static

◆ equals()

virtual bool Lucene::FuzzyQuery::equals ( const LuceneObjectPtr other)
virtual

Return whether two objects are equal.

Reimplemented from Lucene::MultiTermQuery.

◆ getClassName()

virtual String Lucene::FuzzyQuery::getClassName ( )
inlinevirtual

Reimplemented from Lucene::MultiTermQuery.

◆ getEnum()

virtual FilteredTermEnumPtr Lucene::FuzzyQuery::getEnum ( const IndexReaderPtr reader)
protectedvirtual

Construct the enumeration to be used, expanding the pattern term.

Implements Lucene::MultiTermQuery.

◆ getMinSimilarity()

double Lucene::FuzzyQuery::getMinSimilarity ( )

Returns the minimum similarity that is required for this query to match.

Returns
float value between 0.0 and 1.0

◆ getPrefixLength()

int32_t Lucene::FuzzyQuery::getPrefixLength ( )

Returns the non-fuzzy prefix length. This is the number of characters at the start of a term that must be identical (not fuzzy) to the query term if the query is to match that term.

◆ getTerm()

TermPtr Lucene::FuzzyQuery::getTerm ( )

Returns the pattern term.

◆ hashCode()

virtual int32_t Lucene::FuzzyQuery::hashCode ( )
virtual

Return hash code for this object.

Reimplemented from Lucene::MultiTermQuery.

◆ rewrite()

virtual QueryPtr Lucene::FuzzyQuery::rewrite ( const IndexReaderPtr reader)
virtual

Called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.

Reimplemented from Lucene::MultiTermQuery.

◆ setRewriteMethod()

virtual void Lucene::FuzzyQuery::setRewriteMethod ( const RewriteMethodPtr method)
virtual

Sets the rewrite method to be used when executing the query. You can use one of the four core methods, or implement your own subclass of RewriteMethod.

Reimplemented from Lucene::MultiTermQuery.

◆ shared_from_this()

boost::shared_ptr< FuzzyQuery > Lucene::FuzzyQuery::shared_from_this ( )
inline

◆ toString()

virtual String Lucene::FuzzyQuery::toString ( const String &  field)
virtual

Prints a query to a string, with field assumed to be the default field and omitted.

The representation used is one that is supposed to be readable by QueryParser. However, there are the following limitations:

If the query was created by the parser, the printed representation may not be exactly what was parsed. For example, characters that need to be escaped will be represented without the required backslash.

Some of the more complicated queries (eg. span queries) don't have a representation that can be parsed by QueryParser.

Reimplemented from Lucene::Query.

Field Documentation

◆ defaultPrefixLength

const int32_t Lucene::FuzzyQuery::defaultPrefixLength
static

◆ minimumSimilarity

double Lucene::FuzzyQuery::minimumSimilarity
protected

◆ prefixLength

int32_t Lucene::FuzzyQuery::prefixLength
protected

◆ term

TermPtr Lucene::FuzzyQuery::term
protected

◆ termLongEnough

bool Lucene::FuzzyQuery::termLongEnough
protected

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

clucene.sourceforge.net