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search_fuzzy.go
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search_fuzzy.go
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// Copyright (c) 2014 Couchbase, Inc.
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed under the
// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.
package searchers
import (
"github.com/blevesearch/bleve/index"
"github.com/blevesearch/bleve/search"
)
type FuzzySearcher struct {
indexReader index.IndexReader
term string
prefix int
fuzziness int
field string
explain bool
searcher *DisjunctionSearcher
}
func NewFuzzySearcher(indexReader index.IndexReader, term string, prefix, fuzziness int, field string, boost float64, explain bool) (*FuzzySearcher, error) {
prefixTerm := ""
for i, r := range term {
if i < prefix {
prefixTerm += string(r)
}
}
// find the terms with this prefix
var fieldDict index.FieldDict
var err error
if len(prefixTerm) > 0 {
fieldDict, err = indexReader.FieldDictPrefix(field, []byte(prefixTerm))
} else {
fieldDict, err = indexReader.FieldDict(field)
}
// enumerate terms and check levenshtein distance
candidateTerms := make([]string, 0)
tfd, err := fieldDict.Next()
for err == nil && tfd != nil {
ld, exceeded := search.LevenshteinDistanceMax(&term, &tfd.Term, fuzziness)
if !exceeded && ld <= fuzziness {
candidateTerms = append(candidateTerms, tfd.Term)
}
tfd, err = fieldDict.Next()
}
if err != nil {
return nil, err
}
err = fieldDict.Close()
if err != nil {
return nil, err
}
// enumerate all the terms in the range
qsearchers := make([]search.Searcher, 0, 25)
for _, cterm := range candidateTerms {
qsearcher, err := NewTermSearcher(indexReader, cterm, field, boost, explain)
if err != nil {
return nil, err
}
qsearchers = append(qsearchers, qsearcher)
}
// build disjunction searcher of these ranges
searcher, err := NewDisjunctionSearcher(indexReader, qsearchers, 0, explain)
if err != nil {
return nil, err
}
return &FuzzySearcher{
indexReader: indexReader,
term: term,
prefix: prefix,
fuzziness: fuzziness,
field: field,
explain: explain,
searcher: searcher,
}, nil
}
func (s *FuzzySearcher) Count() uint64 {
return s.searcher.Count()
}
func (s *FuzzySearcher) Weight() float64 {
return s.searcher.Weight()
}
func (s *FuzzySearcher) SetQueryNorm(qnorm float64) {
s.searcher.SetQueryNorm(qnorm)
}
func (s *FuzzySearcher) Next() (*search.DocumentMatch, error) {
return s.searcher.Next()
}
func (s *FuzzySearcher) Advance(ID string) (*search.DocumentMatch, error) {
return s.searcher.Next()
}
func (s *FuzzySearcher) Close() error {
return s.searcher.Close()
}
func (s *FuzzySearcher) Min() int {
return 0
}