Adding upstream version 2.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

search/searcher/search_regexp.go

@@ -0,0 +1,169 @@
+//  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 (
+	"context"
+	"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(ctx context.Context, 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(ctx, indexReader, r, field, boost, options)
+	}
+
+	fieldDict, a, err := ir.FieldDictRegexpAutomaton(field, pattern)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		if cerr := fieldDict.Close(); cerr != nil && err == nil {
+			err = cerr
+		}
+	}()
+
+	var termSet = make(map[string]struct{})
+	var candidateTerms []string
+
+	tfd, err := fieldDict.Next()
+	for err == nil && tfd != nil {
+		if _, exists := termSet[tfd.Term]; !exists {
+			termSet[tfd.Term] = struct{}{}
+			candidateTerms = append(candidateTerms, tfd.Term)
+			tfd, err = fieldDict.Next()
+		}
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	if ctx != nil {
+		if fts, ok := ctx.Value(search.FieldTermSynonymMapKey).(search.FieldTermSynonymMap); ok {
+			if ts, exists := fts[field]; exists {
+				for term := range ts {
+					if _, exists := termSet[term]; exists {
+						continue
+					}
+					if a.MatchesRegex(term) {
+						termSet[term] = struct{}{}
+						candidateTerms = append(candidateTerms, term)
+					}
+				}
+			}
+		}
+	}
+
+	return NewMultiTermSearcher(ctx, 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(ctx context.Context, indexReader index.IndexReader, pattern Regexp,
+	field string, boost float64, options search.SearcherOptions) (
+	search.Searcher, error) {
+	var candidateTerms []string
+	var regexpCandidates *regexpCandidates
+	prefixTerm, complete := pattern.LiteralPrefix()
+	if complete {
+		// there is no pattern
+		candidateTerms = []string{prefixTerm}
+	} else {
+		var err error
+		regexpCandidates, err = findRegexpCandidateTerms(indexReader, pattern, field,
+			prefixTerm)
+		if err != nil {
+			return nil, err
+		}
+	}
+	var dictBytesRead uint64
+	if regexpCandidates != nil {
+		candidateTerms = regexpCandidates.candidates
+		dictBytesRead = regexpCandidates.bytesRead
+	}
+
+	if ctx != nil {
+		reportIOStats(ctx, dictBytesRead)
+		search.RecordSearchCost(ctx, search.AddM, dictBytesRead)
+	}
+
+	return NewMultiTermSearcher(ctx, indexReader, candidateTerms, field, boost,
+		options, true)
+}
+
+type regexpCandidates struct {
+	candidates []string
+	bytesRead  uint64
+}
+
+func findRegexpCandidateTerms(indexReader index.IndexReader,
+	pattern Regexp, field, prefixTerm string) (rv *regexpCandidates, err error) {
+	rv = &regexpCandidates{
+		candidates: 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.candidates = append(rv.candidates, tfd.Term)
+			if tooManyClauses(len(rv.candidates)) {
+				return rv, tooManyClausesErr(field, len(rv.candidates))
+			}
+		}
+		tfd, err = fieldDict.Next()
+	}
+	rv.bytesRead = fieldDict.BytesRead()
+	return rv, err
+}