/
search_regexp.go
131 lines (113 loc) · 3.73 KB
/
search_regexp.go
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// Copyright (c) 2015 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 (
"regexp"
"github.com/blevesearch/bleve/v2/search"
index "github.com/blevesearch/bleve_index_api"
)
// The Regexp interface defines the subset of the regexp.Regexp API
// methods that are used by bleve indexes, allowing callers to pass in
// alternate implementations.
type Regexp interface {
FindStringIndex(s string) (loc []int)
LiteralPrefix() (prefix string, complete bool)
String() string
}
// NewRegexpStringSearcher is similar to NewRegexpSearcher, but
// additionally optimizes for index readers that handle regexp's.
func NewRegexpStringSearcher(indexReader index.IndexReader, pattern string,
field string, boost float64, options search.SearcherOptions) (
search.Searcher, error) {
ir, ok := indexReader.(index.IndexReaderRegexp)
if !ok {
r, err := regexp.Compile(pattern)
if err != nil {
return nil, err
}
return NewRegexpSearcher(indexReader, r, field, boost, options)
}
fieldDict, err := ir.FieldDictRegexp(field, pattern)
if err != nil {
return nil, err
}
defer func() {
if cerr := fieldDict.Close(); cerr != nil && err == nil {
err = cerr
}
}()
var candidateTerms []string
tfd, err := fieldDict.Next()
for err == nil && tfd != nil {
candidateTerms = append(candidateTerms, tfd.Term)
tfd, err = fieldDict.Next()
}
if err != nil {
return nil, err
}
return NewMultiTermSearcher(indexReader, candidateTerms, field, boost,
options, true)
}
// NewRegexpSearcher creates a searcher which will match documents that
// contain terms which match the pattern regexp. The match must be EXACT
// matching the entire term. The provided regexp SHOULD NOT start with ^
// or end with $ as this can intefere with the implementation. Separately,
// matches will be checked to ensure they match the entire term.
func NewRegexpSearcher(indexReader index.IndexReader, pattern Regexp,
field string, boost float64, options search.SearcherOptions) (
search.Searcher, error) {
var candidateTerms []string
prefixTerm, complete := pattern.LiteralPrefix()
if complete {
// there is no pattern
candidateTerms = []string{prefixTerm}
} else {
var err error
candidateTerms, err = findRegexpCandidateTerms(indexReader, pattern, field,
prefixTerm)
if err != nil {
return nil, err
}
}
return NewMultiTermSearcher(indexReader, candidateTerms, field, boost,
options, true)
}
func findRegexpCandidateTerms(indexReader index.IndexReader,
pattern Regexp, 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 the terms and check against regexp
tfd, err := fieldDict.Next()
for err == nil && tfd != nil {
matchPos := pattern.FindStringIndex(tfd.Term)
if matchPos != nil && matchPos[0] == 0 && matchPos[1] == len(tfd.Term) {
rv = append(rv, tfd.Term)
if tooManyClauses(len(rv)) {
return rv, tooManyClausesErr(field, len(rv))
}
}
tfd, err = fieldDict.Next()
}
return rv, err
}