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121 lines
3.4 KiB
121 lines
3.4 KiB
// Copyright (c) 2015 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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"regexp"
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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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// NewRegexpStringSearcher is similar to NewRegexpSearcher, but
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// additionally optimizes for index readers that handle regexp's.
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func NewRegexpStringSearcher(indexReader index.IndexReader, pattern string,
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field string, boost float64, options search.SearcherOptions) (
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search.Searcher, error) {
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ir, ok := indexReader.(index.IndexReaderRegexp)
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if !ok {
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r, err := regexp.Compile(pattern)
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if err != nil {
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return nil, err
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}
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return NewRegexpSearcher(indexReader, r, field, boost, options)
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}
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fieldDict, err := ir.FieldDictRegexp(field, pattern)
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if err != nil {
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return nil, err
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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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var candidateTerms []string
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tfd, err := fieldDict.Next()
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for err == nil && tfd != nil {
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candidateTerms = append(candidateTerms, tfd.Term)
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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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return NewMultiTermSearcher(indexReader, candidateTerms, field, boost,
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options, true)
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}
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// NewRegexpSearcher creates a searcher which will match documents that
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// contain terms which match the pattern regexp. The match must be EXACT
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// matching the entire term. The provided regexp SHOULD NOT start with ^
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// or end with $ as this can intefere with the implementation. Separately,
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// matches will be checked to ensure they match the entire term.
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func NewRegexpSearcher(indexReader index.IndexReader, pattern index.Regexp,
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field string, boost float64, options search.SearcherOptions) (
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search.Searcher, error) {
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var candidateTerms []string
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prefixTerm, complete := pattern.LiteralPrefix()
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if complete {
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// there is no pattern
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candidateTerms = []string{prefixTerm}
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} else {
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var err error
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candidateTerms, err = findRegexpCandidateTerms(indexReader, pattern, field,
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prefixTerm)
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if err != nil {
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return nil, err
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}
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}
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return NewMultiTermSearcher(indexReader, candidateTerms, field, boost,
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options, true)
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}
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func findRegexpCandidateTerms(indexReader index.IndexReader,
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pattern index.Regexp, 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 the terms and check against regexp
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tfd, err := fieldDict.Next()
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for err == nil && tfd != nil {
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matchPos := pattern.FindStringIndex(tfd.Term)
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if matchPos != nil && matchPos[0] == 0 && matchPos[1] == len(tfd.Term) {
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rv = append(rv, tfd.Term)
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if tooManyClauses(len(rv)) {
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return rv, tooManyClausesErr(field, len(rv))
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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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