Search bar for issues/pulls (#530)

vendor/github.com/blevesearch/bleve/search/searcher/search_fuzzy.go

@@ -0,0 +1,143 @@
+//  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 searcher
+
+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) {
+	// Note: we don't byte slice the term for a prefix because of runes.
+	prefixTerm := ""
+	for i, r := range term {
+		if i < prefix {
+			prefixTerm += string(r)
+		} else {
+			break
+		}
+	}
+
+	candidateTerms, err := findFuzzyCandidateTerms(indexReader, term, fuzziness, field, prefixTerm)
+	if err != nil {
+		return nil, err
+	}
+
+	// enumerate all the terms in the range
+	qsearchers := make([]search.Searcher, 0, len(candidateTerms))
+	qsearchersClose := func() {
+		for _, searcher := range qsearchers {
+			_ = searcher.Close()
+		}
+	}
+	for _, cterm := range candidateTerms {
+		qsearcher, err := NewTermSearcher(indexReader, cterm, field, boost, explain)
+		if err != nil {
+			qsearchersClose()
+			return nil, err
+		}
+		qsearchers = append(qsearchers, qsearcher)
+	}
+
+	// build disjunction searcher of these ranges
+	searcher, err := NewDisjunctionSearcher(indexReader, qsearchers, 0, explain)
+	if err != nil {
+		qsearchersClose()
+		return nil, err
+	}
+
+	return &FuzzySearcher{
+		indexReader: indexReader,
+		term:        term,
+		prefix:      prefix,
+		fuzziness:   fuzziness,
+		field:       field,
+		explain:     explain,
+		searcher:    searcher,
+	}, nil
+}
+
+func findFuzzyCandidateTerms(indexReader index.IndexReader, term string, fuzziness int, field, prefixTerm string) (rv []string, err error) {
+	rv = make([]string, 0)
+	var fieldDict index.FieldDict
+	if len(prefixTerm) > 0 {
+		fieldDict, err = indexReader.FieldDictPrefix(field, []byte(prefixTerm))
+	} else {
+		fieldDict, err = indexReader.FieldDict(field)
+	}
+	defer func() {
+		if cerr := fieldDict.Close(); cerr != nil && err == nil {
+			err = cerr
+		}
+	}()
+
+	// enumerate terms and check levenshtein distance
+	tfd, err := fieldDict.Next()
+	for err == nil && tfd != nil {
+		ld, exceeded := search.LevenshteinDistanceMax(term, tfd.Term, fuzziness)
+		if !exceeded && ld <= fuzziness {
+			rv = append(rv, tfd.Term)
+			if tooManyClauses(len(rv)) {
+				return rv, tooManyClausesErr()
+			}
+		}
+		tfd, err = fieldDict.Next()
+	}
+
+	return rv, err
+}
+
+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(ctx *search.SearchContext) (*search.DocumentMatch, error) {
+	return s.searcher.Next(ctx)
+
+}
+
+func (s *FuzzySearcher) Advance(ctx *search.SearchContext, ID index.IndexInternalID) (*search.DocumentMatch, error) {
+	return s.searcher.Advance(ctx, ID)
+}
+
+func (s *FuzzySearcher) Close() error {
+	return s.searcher.Close()
+}
+
+func (s *FuzzySearcher) Min() int {
+	return 0
+}
+
+func (s *FuzzySearcher) DocumentMatchPoolSize() int {
+	return s.searcher.DocumentMatchPoolSize()
+}