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Diffstat (limited to '3rdparty/clucene/src/CLucene/search/FuzzyQuery.h')
| -rw-r--r-- | 3rdparty/clucene/src/CLucene/search/FuzzyQuery.h | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/3rdparty/clucene/src/CLucene/search/FuzzyQuery.h b/3rdparty/clucene/src/CLucene/search/FuzzyQuery.h new file mode 100644 index 000000000..e58637bb9 --- /dev/null +++ b/3rdparty/clucene/src/CLucene/search/FuzzyQuery.h @@ -0,0 +1,156 @@ +/*------------------------------------------------------------------------------ +* Copyright (C) 2003-2006 Ben van Klinken and the CLucene Team +* +* Distributable under the terms of either the Apache License (Version 2.0) or +* the GNU Lesser General Public License, as specified in the COPYING file. +------------------------------------------------------------------------------*/ +#ifndef _lucene_search_FuzzyQuery_ +#define _lucene_search_FuzzyQuery_ + +#if defined(_LUCENE_PRAGMA_ONCE) +# pragma once +#endif + +#include "CLucene/index/IndexReader.h" +#include "CLucene/index/Term.h" +#include "MultiTermQuery.h" + + +CL_NS_DEF(search) + + // class FuzzyQuery implements the fuzzy search query + class FuzzyQuery: public MultiTermQuery { + private: + qreal minimumSimilarity; + size_t prefixLength; + protected: + FuzzyQuery(const FuzzyQuery& clone); + public: + static qreal defaultMinSimilarity; + + /** + * Create a new FuzzyQuery that will match terms with a similarity + * of at least <code>minimumSimilarity</code> to <code>term</code>. + * If a <code>prefixLength</code> > 0 is specified, a common prefix + * of that length is also required. + * + * @param term the term to search for + * @param minimumSimilarity a value between 0 and 1 to set the required similarity + * between the query term and the matching terms. For example, for a + * <code>minimumSimilarity</code> of <code>0.5</code> 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 <code>length(term)*0.5</code> + * @param prefixLength length of common (non-fuzzy) prefix + * @throws IllegalArgumentException if minimumSimilarity is > 1 or < 0 + * or if prefixLength < 0 or > <code>term.text().length()</code>. + */ + FuzzyQuery(CL_NS(index)::Term* term, qreal minimumSimilarity=defaultMinSimilarity, size_t prefixLength=0); + //Destructor + ~FuzzyQuery(); + + TCHAR* toString(const TCHAR* field) const; + + //Returns the name "FuzzyQuery" + static const TCHAR* getClassName(); + const TCHAR* getQueryName() const; + + Query* clone() const; + bool equals(Query * other) const; + size_t hashCode() const; + + /** + * Returns the minimum similarity that is required for this query to match. + * @return float value between 0.0 and 1.0 + */ + qreal getMinSimilarity() const; + + /** + * Returns the prefix length, i.e. 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. + */ + size_t getPrefixLength() const; + + protected: + FilteredTermEnum* getEnum(CL_NS(index)::IndexReader* reader); + }; + + /** FuzzyTermEnum is a subclass of FilteredTermEnum for enumerating all + * terms that are similiar to the specified filter term. + * + * Term enumerations are always ordered by Term.compareTo(). Each term in + * the enumeration is greater than all that precede it. + */ + class FuzzyTermEnum: public FilteredTermEnum { + private: + qreal distance; + bool _endEnum; + + CL_NS(index)::Term* searchTerm; + TCHAR* text; + size_t textLen; + TCHAR* prefix; + size_t prefixLength; + qreal minimumSimilarity; + double scale_factor; + + + /** + * This static array saves us from the time required to create a new array + * everytime editDistance is called. + */ + int32_t* e; + int32_t eWidth; + int32_t eHeight; + + /****************************** + * Compute Levenshtein distance + ******************************/ + + /** + Levenshtein distance also known as edit distance is a measure of similiarity + between two strings where the distance is measured as the number of character + deletions, insertions or substitutions required to transform one string to + the other string. + <p>This method takes in four parameters; two strings and their respective + lengths to compute the Levenshtein distance between the two strings. + The result is returned as an integer. + */ + int32_t editDistance(const TCHAR* s, const TCHAR* t, const int32_t n, const int32_t m) ; + + protected: + /** + The termCompare method in FuzzyTermEnum uses Levenshtein distance to + calculate the distance between the given term and the comparing term. + */ + bool termCompare(CL_NS(index)::Term* term) ; + + ///Returns the fact if the current term in the enumeration has reached the end + bool endEnum(); + public: + + /** + * Empty prefix and minSimilarity of 0.5f are used. + * + * @param reader + * @param term + * @throws IOException + * @see #FuzzyTermEnum(IndexReader, Term, qreal, int32_t) + */ + FuzzyTermEnum(const CL_NS(index)::IndexReader* reader, CL_NS(index)::Term* term, qreal minSimilarity=FuzzyQuery::defaultMinSimilarity, size_t prefixLength=0); + /** Destructor */ + ~FuzzyTermEnum(); + /** Close the enumeration */ + void close(); + + /** Returns the difference between the distance and the fuzzy threshold + * multiplied by the scale factor + */ + qreal difference(); + + + const char* getObjectName(){ return FuzzyTermEnum::getClassName(); } + static const char* getClassName(){ return "FuzzyTermEnum"; } + }; +CL_NS_END +#endif |