144 lines
3.7 KiB
Go
144 lines
3.7 KiB
Go
// Copyright (c) 2014 Couchbase, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package searcher
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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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// Note: we don't byte slice the term for a prefix because of runes.
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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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} else {
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break
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}
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}
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candidateTerms, err := findFuzzyCandidateTerms(indexReader, term, fuzziness, field, prefixTerm)
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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, len(candidateTerms))
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qsearchersClose := func() {
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for _, searcher := range qsearchers {
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_ = searcher.Close()
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}
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}
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for _, cterm := range candidateTerms {
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qsearcher, err := NewTermSearcher(indexReader, cterm, field, boost, explain)
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if err != nil {
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qsearchersClose()
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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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qsearchersClose()
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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 findFuzzyCandidateTerms(indexReader index.IndexReader, term string, fuzziness int, field, prefixTerm string) (rv []string, err error) {
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rv = make([]string, 0)
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var fieldDict index.FieldDict
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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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defer func() {
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if cerr := fieldDict.Close(); cerr != nil && err == nil {
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err = cerr
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}
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}()
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// enumerate terms and check levenshtein distance
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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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rv = append(rv, tfd.Term)
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if tooManyClauses(len(rv)) {
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return rv, tooManyClausesErr()
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}
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}
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tfd, err = fieldDict.Next()
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}
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return rv, err
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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(ctx *search.SearchContext) (*search.DocumentMatch, error) {
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return s.searcher.Next(ctx)
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}
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func (s *FuzzySearcher) Advance(ctx *search.SearchContext, ID index.IndexInternalID) (*search.DocumentMatch, error) {
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return s.searcher.Advance(ctx, ID)
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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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func (s *FuzzySearcher) DocumentMatchPoolSize() int {
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return s.searcher.DocumentMatchPoolSize()
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}
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