113 lines
2.9 KiB
Go
113 lines
2.9 KiB
Go
// Copyright (c) 2014 Couchbase, Inc.
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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// except in compliance with the License. You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software distributed under the
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// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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// either express or implied. See the License for the specific language governing permissions
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// and limitations under the License.
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package searchers
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import (
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"github.com/blevesearch/bleve/index"
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"github.com/blevesearch/bleve/search"
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)
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type FuzzySearcher struct {
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indexReader index.IndexReader
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term string
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prefix int
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fuzziness int
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field string
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explain bool
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searcher *DisjunctionSearcher
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}
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func NewFuzzySearcher(indexReader index.IndexReader, term string, prefix, fuzziness int, field string, boost float64, explain bool) (*FuzzySearcher, error) {
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prefixTerm := ""
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for i, r := range term {
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if i < prefix {
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prefixTerm += string(r)
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}
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}
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// find the terms with this prefix
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var fieldDict index.FieldDict
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var err error
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if len(prefixTerm) > 0 {
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fieldDict, err = indexReader.FieldDictPrefix(field, []byte(prefixTerm))
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} else {
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fieldDict, err = indexReader.FieldDict(field)
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}
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// enumerate terms and check levenshtein distance
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candidateTerms := make([]string, 0)
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tfd, err := fieldDict.Next()
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for err == nil && tfd != nil {
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ld, exceeded := search.LevenshteinDistanceMax(&term, &tfd.Term, fuzziness)
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if !exceeded && ld <= fuzziness {
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candidateTerms = append(candidateTerms, tfd.Term)
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}
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tfd, err = fieldDict.Next()
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}
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if err != nil {
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return nil, err
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}
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// enumerate all the terms in the range
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qsearchers := make([]search.Searcher, 0, 25)
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for _, cterm := range candidateTerms {
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qsearcher, err := NewTermSearcher(indexReader, cterm, field, 1.0, explain)
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if err != nil {
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return nil, err
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}
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qsearchers = append(qsearchers, qsearcher)
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}
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// build disjunction searcher of these ranges
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searcher, err := NewDisjunctionSearcher(indexReader, qsearchers, 0, explain)
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if err != nil {
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return nil, err
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}
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return &FuzzySearcher{
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indexReader: indexReader,
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term: term,
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prefix: prefix,
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fuzziness: fuzziness,
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field: field,
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explain: explain,
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searcher: searcher,
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}, nil
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}
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func (s *FuzzySearcher) Count() uint64 {
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return s.searcher.Count()
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}
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func (s *FuzzySearcher) Weight() float64 {
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return s.searcher.Weight()
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}
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func (s *FuzzySearcher) SetQueryNorm(qnorm float64) {
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s.searcher.SetQueryNorm(qnorm)
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}
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func (s *FuzzySearcher) Next() (*search.DocumentMatch, error) {
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return s.searcher.Next()
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}
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func (s *FuzzySearcher) Advance(ID string) (*search.DocumentMatch, error) {
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return s.searcher.Next()
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}
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func (s *FuzzySearcher) Close() error {
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return s.searcher.Close()
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}
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func (s *FuzzySearcher) Min() int {
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return 0
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}
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