Adding upstream version 2.5.1.

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

search/highlight/highlighter/simple/highlighter_simple.go

@@ -0,0 +1,225 @@
+//  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 (
+	"container/heap"
+	"fmt"
+
+	index "github.com/blevesearch/bleve_index_api"
+
+	"github.com/blevesearch/bleve/v2/registry"
+	"github.com/blevesearch/bleve/v2/search"
+	"github.com/blevesearch/bleve/v2/search/highlight"
+)
+
+const Name = "simple"
+const DefaultSeparator = "…"
+
+type Highlighter struct {
+	fragmenter highlight.Fragmenter
+	formatter  highlight.FragmentFormatter
+	sep        string
+}
+
+func NewHighlighter(fragmenter highlight.Fragmenter, formatter highlight.FragmentFormatter, separator string) *Highlighter {
+	return &Highlighter{
+		fragmenter: fragmenter,
+		formatter:  formatter,
+		sep:        separator,
+	}
+}
+
+func (s *Highlighter) Fragmenter() highlight.Fragmenter {
+	return s.fragmenter
+}
+
+func (s *Highlighter) SetFragmenter(f highlight.Fragmenter) {
+	s.fragmenter = f
+}
+
+func (s *Highlighter) FragmentFormatter() highlight.FragmentFormatter {
+	return s.formatter
+}
+
+func (s *Highlighter) SetFragmentFormatter(f highlight.FragmentFormatter) {
+	s.formatter = f
+}
+
+func (s *Highlighter) Separator() string {
+	return s.sep
+}
+
+func (s *Highlighter) SetSeparator(sep string) {
+	s.sep = sep
+}
+
+func (s *Highlighter) BestFragmentInField(dm *search.DocumentMatch, doc index.Document, field string) string {
+	fragments := s.BestFragmentsInField(dm, doc, field, 1)
+	if len(fragments) > 0 {
+		return fragments[0]
+	}
+	return ""
+}
+
+func (s *Highlighter) BestFragmentsInField(dm *search.DocumentMatch, doc index.Document, field string, num int) []string {
+	tlm := dm.Locations[field]
+	orderedTermLocations := highlight.OrderTermLocations(tlm)
+	scorer := NewFragmentScorer(tlm)
+
+	// score the fragments and put them into a priority queue ordered by score
+	fq := make(FragmentQueue, 0)
+	heap.Init(&fq)
+	doc.VisitFields(func(f index.Field) {
+		if f.Name() == field {
+			_, ok := f.(index.TextField)
+			if ok {
+				termLocationsSameArrayPosition := make(highlight.TermLocations, 0)
+				for _, otl := range orderedTermLocations {
+					if otl.ArrayPositions.Equals(f.ArrayPositions()) {
+						termLocationsSameArrayPosition = append(termLocationsSameArrayPosition, otl)
+					}
+				}
+
+				fieldData := f.Value()
+				fragments := s.fragmenter.Fragment(fieldData, termLocationsSameArrayPosition)
+				for _, fragment := range fragments {
+					fragment.ArrayPositions = f.ArrayPositions()
+					scorer.Score(fragment)
+					heap.Push(&fq, fragment)
+				}
+			}
+		}
+	})
+
+	// now find the N best non-overlapping fragments
+	var bestFragments []*highlight.Fragment
+	if len(fq) > 0 {
+		candidate := heap.Pop(&fq)
+	OUTER:
+		for candidate != nil && len(bestFragments) < num {
+			// see if this overlaps with any of the best already identified
+			if len(bestFragments) > 0 {
+				for _, frag := range bestFragments {
+					if candidate.(*highlight.Fragment).Overlaps(frag) {
+						if len(fq) < 1 {
+							break OUTER
+						}
+						candidate = heap.Pop(&fq)
+						continue OUTER
+					}
+				}
+				bestFragments = append(bestFragments, candidate.(*highlight.Fragment))
+			} else {
+				bestFragments = append(bestFragments, candidate.(*highlight.Fragment))
+			}
+
+			if len(fq) < 1 {
+				break
+			}
+			candidate = heap.Pop(&fq)
+		}
+	}
+
+	// now that we have the best fragments, we can format them
+	orderedTermLocations.MergeOverlapping()
+	formattedFragments := make([]string, len(bestFragments))
+	for i, fragment := range bestFragments {
+		formattedFragments[i] = ""
+		if fragment.Start != 0 {
+			formattedFragments[i] += s.sep
+		}
+		formattedFragments[i] += s.formatter.Format(fragment, orderedTermLocations)
+		if fragment.End != len(fragment.Orig) {
+			formattedFragments[i] += s.sep
+		}
+	}
+
+	if dm.Fragments == nil {
+		dm.Fragments = make(search.FieldFragmentMap, 0)
+	}
+	if len(formattedFragments) > 0 {
+		dm.Fragments[field] = formattedFragments
+	}
+
+	return formattedFragments
+}
+
+// FragmentQueue implements heap.Interface and holds Items.
+type FragmentQueue []*highlight.Fragment
+
+func (fq FragmentQueue) Len() int { return len(fq) }
+
+func (fq FragmentQueue) Less(i, j int) bool {
+	// We want Pop to give us the highest, not lowest, priority so we use greater-than here.
+	return fq[i].Score > fq[j].Score
+}
+
+func (fq FragmentQueue) Swap(i, j int) {
+	fq[i], fq[j] = fq[j], fq[i]
+	fq[i].Index = i
+	fq[j].Index = j
+}
+
+func (fq *FragmentQueue) Push(x interface{}) {
+	n := len(*fq)
+	item := x.(*highlight.Fragment)
+	item.Index = n
+	*fq = append(*fq, item)
+}
+
+func (fq *FragmentQueue) Pop() interface{} {
+	old := *fq
+	n := len(old)
+	item := old[n-1]
+	item.Index = -1 // for safety
+	*fq = old[0 : n-1]
+	return item
+}
+
+func Constructor(config map[string]interface{}, cache *registry.Cache) (highlight.Highlighter, error) {
+	separator := DefaultSeparator
+	separatorVal, ok := config["separator"].(string)
+	if ok {
+		separator = separatorVal
+	}
+
+	fragmenterName, ok := config["fragmenter"].(string)
+	if !ok {
+		return nil, fmt.Errorf("must specify fragmenter")
+	}
+	fragmenter, err := cache.FragmenterNamed(fragmenterName)
+	if err != nil {
+		return nil, fmt.Errorf("error building fragmenter: %v", err)
+	}
+
+	formatterName, ok := config["formatter"].(string)
+	if !ok {
+		return nil, fmt.Errorf("must specify formatter")
+	}
+	formatter, err := cache.FragmentFormatterNamed(formatterName)
+	if err != nil {
+		return nil, fmt.Errorf("error building fragment formatter: %v", err)
+	}
+
+	return NewHighlighter(fragmenter, formatter, separator), nil
+}
+
+func init() {
+	err := registry.RegisterHighlighter(Name, Constructor)
+	if err != nil {
+		panic(err)
+	}
+}