Adding upstream version 2.5.1.

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

search/highlight/fragmenter/simple/simple.go

@@ -0,0 +1,156 @@
+//  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 simple
+
+import (
+	"unicode/utf8"
+
+	"github.com/blevesearch/bleve/v2/registry"
+	"github.com/blevesearch/bleve/v2/search/highlight"
+)
+
+const Name = "simple"
+
+const defaultFragmentSize = 200
+
+type Fragmenter struct {
+	fragmentSize int
+}
+
+func NewFragmenter(fragmentSize int) *Fragmenter {
+	return &Fragmenter{
+		fragmentSize: fragmentSize,
+	}
+}
+
+func (s *Fragmenter) Fragment(orig []byte, ot highlight.TermLocations) []*highlight.Fragment {
+	var rv []*highlight.Fragment
+	maxbegin := 0
+OUTER:
+	for currTermIndex, termLocation := range ot {
+		// start with this
+		// it should be the highest scoring fragment with this term first
+		start := termLocation.Start
+		end := start
+		used := 0
+		for end < len(orig) && used < s.fragmentSize {
+			r, size := utf8.DecodeRune(orig[end:])
+			if r == utf8.RuneError {
+				continue OUTER // bail
+			}
+			end += size
+			used++
+		}
+
+		// if we still have more characters available to us
+		// push back towards beginning
+		// without cross maxbegin
+		for start > 0 && used < s.fragmentSize {
+			if start > len(orig) {
+				// bail if out of bounds, possibly due to token replacement
+				// e.g with a regexp replacement
+				continue OUTER
+			}
+			r, size := utf8.DecodeLastRune(orig[0:start])
+			if r == utf8.RuneError {
+				continue OUTER // bail
+			}
+			if start-size >= maxbegin {
+				start -= size
+				used++
+			} else {
+				break
+			}
+		}
+
+		// however, we'd rather have the tokens centered more in the frag
+		// lets try to do that as best we can, without affecting the score
+		// find the end of the last term in this fragment
+		minend := end
+		for _, innerTermLocation := range ot[currTermIndex:] {
+			if innerTermLocation.End > end {
+				break
+			}
+			minend = innerTermLocation.End
+		}
+
+		// find the smaller of the two rooms to move
+		roomToMove := utf8.RuneCount(orig[minend:end])
+		roomToMoveStart := 0
+		if start >= maxbegin {
+			roomToMoveStart = utf8.RuneCount(orig[maxbegin:start])
+		}
+		if roomToMoveStart < roomToMove {
+			roomToMove = roomToMoveStart
+		}
+
+		offset := roomToMove / 2
+
+		for offset > 0 {
+			r, size := utf8.DecodeLastRune(orig[0:start])
+			if r == utf8.RuneError {
+				continue OUTER // bail
+			}
+			start -= size
+
+			r, size = utf8.DecodeLastRune(orig[0:end])
+			if r == utf8.RuneError {
+				continue OUTER // bail
+			}
+			end -= size
+			offset--
+		}
+
+		rv = append(rv, &highlight.Fragment{Orig: orig, Start: start - offset, End: end - offset})
+		// set maxbegin to the end of the current term location
+		// so that next one won't back up to include it
+		maxbegin = termLocation.End
+
+	}
+	if len(ot) == 0 {
+		// if there were no terms to highlight
+		// produce a single fragment from the beginning
+		start := 0
+		end := start
+		used := 0
+		for end < len(orig) && used < s.fragmentSize {
+			r, size := utf8.DecodeRune(orig[end:])
+			if r == utf8.RuneError {
+				break
+			}
+			end += size
+			used++
+		}
+		rv = append(rv, &highlight.Fragment{Orig: orig, Start: start, End: end})
+	}
+
+	return rv
+}
+
+func Constructor(config map[string]interface{}, cache *registry.Cache) (highlight.Fragmenter, error) {
+	size := defaultFragmentSize
+	sizeVal, ok := config["size"].(float64)
+	if ok {
+		size = int(sizeVal)
+	}
+	return NewFragmenter(size), nil
+}
+
+func init() {
+	err := registry.RegisterFragmenter(Name, Constructor)
+	if err != nil {
+		panic(err)
+	}
+}