org.sindice.siren.search.node

Class NodeFuzzyQuery

java.lang.Object

org.apache.lucene.search.Query

org.sindice.siren.search.node.NodeQuery

org.sindice.siren.search.node.NodePrimitiveQuery

org.sindice.siren.search.node.MultiNodeTermQuery

org.sindice.siren.search.node.NodeFuzzyQuery

All Implemented Interfaces:

Cloneable

public class NodeFuzzyQuery
extends MultiNodeTermQuery

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

This query uses MultiTermQuery.TopTermsScoringBooleanQueryRewrite as default. So terms will be collected and scored according to their edit distance. Only the top terms are used for building the NodeBooleanQuery. It is not recommended to change the rewrite mode for fuzzy queries.

Code taken from FuzzyQuery and adapted for SIREn.

Nested Class Summary

Nested classes/interfaces inherited from class org.sindice.siren.search.node.MultiNodeTermQuery

MultiNodeTermQuery.RewriteMethod

Field Summary

Fields

Modifier and Type	Field and Description
static int	defaultMaxEdits
static int	defaultMaxExpansions
static int	defaultPrefixLength
static boolean	defaultTranspositions

Fields inherited from class org.sindice.siren.search.node.MultiNodeTermQuery

CONSTANT_SCORE_AUTO_REWRITE_DEFAULT, CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE, CONSTANT_SCORE_FILTER_REWRITE, field, rewriteMethod, SCORING_BOOLEAN_QUERY_REWRITE

Fields inherited from class org.sindice.siren.search.node.NodePrimitiveQuery

datatype

Fields inherited from class org.sindice.siren.search.node.NodeQuery

ancestor, levelConstraint, lowerBound, upperBound

Constructor Summary

Constructors

Constructor and Description
NodeFuzzyQuery(org.apache.lucene.index.Term term) Calls SirenFuzzyQuery(term, 0.5f, 0, Integer.MAX_VALUE).
NodeFuzzyQuery(org.apache.lucene.index.Term term, int maxEdits) Calls SirenFuzzyQuery(term, minimumSimilarity, 0, Integer.MAX_VALUE).
NodeFuzzyQuery(org.apache.lucene.index.Term term, int maxEdits, int prefixLength) Calls SirenFuzzyQuery(term, minimumSimilarity, prefixLength, Integer.MAX_VALUE).
NodeFuzzyQuery(org.apache.lucene.index.Term term, int maxEdits, int prefixLength, int maxExpansions, boolean transpositions) Create a new SirenFuzzyQuery that will match terms with a similarity of at least minimumSimilarity to term.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Object obj)
int	getMaxEdits()
int	getPrefixLength() Returns the non-fuzzy prefix length.
org.apache.lucene.index.Term	getTerm() Returns the pattern term.
protected org.apache.lucene.index.TermsEnum	getTermsEnum(org.apache.lucene.index.Terms terms, org.apache.lucene.util.AttributeSource atts) Construct the enumeration to be used, expanding the pattern term.
int	hashCode()
String	toString(String field)

Methods inherited from class org.sindice.siren.search.node.MultiNodeTermQuery

getField, getRewriteMethod, getTermsEnum, rewrite, setRewriteMethod

Methods inherited from class org.sindice.siren.search.node.NodePrimitiveQuery

setDatatype, wrapToStringWithDatatype

Methods inherited from class org.sindice.siren.search.node.NodeQuery

getDocsNodesAndPositionsEnum, getLevelConstraint, getNodeConstraint, setAncestorPointer, setLevelConstraint, setNodeConstraint, setNodeConstraint

Methods inherited from class org.apache.lucene.search.Query

clone, createWeight, extractTerms, getBoost, setBoost, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

defaultMaxEdits

public static final int defaultMaxEdits

See Also:

Constant Field Values

defaultPrefixLength

public static final int defaultPrefixLength

See Also:

Constant Field Values

defaultMaxExpansions

public static final int defaultMaxExpansions

See Also:

Constant Field Values

defaultTranspositions

public static final boolean defaultTranspositions

See Also:

Constant Field Values

Constructor Detail

NodeFuzzyQuery

public NodeFuzzyQuery(org.apache.lucene.index.Term term,
              int maxEdits,
              int prefixLength,
              int maxExpansions,
              boolean transpositions)

Create a new SirenFuzzyQuery 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:

term - the term to search for

maxEdits - must be >= 0 and <= LevenshteinAutomata.MAXIMUM_SUPPORTED_DISTANCE.

prefixLength - length of common (non-fuzzy) prefix

maxExpansions - the maximum number of terms to match. If this number is greater than NodeBooleanQuery.getMaxClauseCount() when the query is rewritten, then the maxClauseCount will be used instead.

transpositions - true if transpositions should be treated as a primitive edit operation. If this is false, comparisons will implement the classic Levenshtein algorithm.

NodeFuzzyQuery

public NodeFuzzyQuery(org.apache.lucene.index.Term term,
              int maxEdits,
              int prefixLength)

Calls SirenFuzzyQuery(term, minimumSimilarity, prefixLength, Integer.MAX_VALUE).

NodeFuzzyQuery

public NodeFuzzyQuery(org.apache.lucene.index.Term term,
              int maxEdits)

Calls SirenFuzzyQuery(term, minimumSimilarity, 0, Integer.MAX_VALUE).

NodeFuzzyQuery

public NodeFuzzyQuery(org.apache.lucene.index.Term term)

Calls SirenFuzzyQuery(term, 0.5f, 0, Integer.MAX_VALUE).

Method Detail

getMaxEdits

public int getMaxEdits()

Returns:

the maximum number of edit distances allowed for this query to match.

getPrefixLength

public int 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.

getTermsEnum

protected org.apache.lucene.index.TermsEnum getTermsEnum(org.apache.lucene.index.Terms terms,
                                             org.apache.lucene.util.AttributeSource atts)
                                                  throws IOException

Description copied from class: MultiNodeTermQuery

Construct the enumeration to be used, expanding the pattern term. This method should only be called if the field exists (ie, implementations can assume the field does exist). This method should not return null (should instead return TermsEnum.EMPTY if no terms match). The TermsEnum must already be positioned to the first matching term. The given AttributeSource is passed by the MultiNodeTermQuery.RewriteMethod to provide attributes, the rewrite method uses to inform about e.g. maximum competitive boosts. This is currently only used by TopNodeTermsRewrite

Specified by:

getTermsEnum in class MultiNodeTermQuery

Throws:

IOException

getTerm

public org.apache.lucene.index.Term getTerm()

Returns the pattern term.

toString

public String toString(String field)

Specified by:

toString in class org.apache.lucene.search.Query

hashCode

public int hashCode()

Overrides:

hashCode in class MultiNodeTermQuery

equals

public boolean equals(Object obj)

Overrides:

equals in class MultiNodeTermQuery