2014-07-30 18:30:38 +02:00
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// Copyright (c) 2014 Couchbase, Inc.
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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// except in compliance with the License. You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software distributed under the
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// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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// either express or implied. See the License for the specific language governing permissions
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// and limitations under the License.
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2014-06-26 17:43:13 +02:00
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package search
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import (
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"container/heap"
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2014-08-28 21:38:57 +02:00
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"github.com/blevesearch/bleve/document"
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2014-06-26 17:43:13 +02:00
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)
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const DEFAULT_SEPARATOR = "…"
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type SimpleHighlighter struct {
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fragmenter Fragmenter
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formatter FragmentFormatter
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sep string
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}
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func NewSimpleHighlighter() *SimpleHighlighter {
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return &SimpleHighlighter{
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fragmenter: NewSimpleFragmenter(),
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formatter: NewANSIFragmentFormatter(),
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sep: DEFAULT_SEPARATOR,
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}
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}
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func (s *SimpleHighlighter) Fragmenter() Fragmenter {
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return s.fragmenter
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}
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func (s *SimpleHighlighter) SetFragmenter(f Fragmenter) {
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s.fragmenter = f
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}
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func (s *SimpleHighlighter) FragmentFormatter() FragmentFormatter {
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return s.formatter
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}
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func (s *SimpleHighlighter) SetFragmentFormatter(f FragmentFormatter) {
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s.formatter = f
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}
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func (s *SimpleHighlighter) Separator() string {
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return s.sep
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}
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func (s *SimpleHighlighter) SetSeparator(sep string) {
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s.sep = sep
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}
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func (s *SimpleHighlighter) BestFragmentInField(dm *DocumentMatch, doc *document.Document, field string) string {
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fragments := s.BestFragmentsInField(dm, doc, field, 1)
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if len(fragments) > 0 {
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return fragments[0]
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}
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return ""
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}
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func (s *SimpleHighlighter) BestFragmentsInField(dm *DocumentMatch, doc *document.Document, field string, num int) []string {
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tlm := dm.Locations[field]
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orderedTermLocations := OrderTermLocations(tlm)
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scorer := NewSimpleFragmentScorer(dm.Locations[field])
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// score the fragments and put them into a priority queue ordered by score
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fq := make(FragmentQueue, 0)
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heap.Init(&fq)
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for _, f := range doc.Fields {
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2014-07-14 20:47:05 +02:00
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if f.Name() == field {
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2014-08-06 19:52:20 +02:00
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_, ok := f.(*document.TextField)
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if ok {
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fieldData := f.Value()
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fragments := s.fragmenter.Fragment(fieldData, orderedTermLocations)
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for _, fragment := range fragments {
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scorer.Score(fragment)
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heap.Push(&fq, fragment)
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}
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2014-06-26 17:43:13 +02:00
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}
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}
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}
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// now find the N best non-overlapping fragments
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bestFragments := make([]*Fragment, 0)
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2014-07-11 20:25:32 +02:00
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if len(fq) > 0 {
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candidate := heap.Pop(&fq)
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OUTER:
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for candidate != nil && len(bestFragments) < num {
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// see if this overlaps with any of the best already identified
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if len(bestFragments) > 0 {
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for _, frag := range bestFragments {
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if candidate.(*Fragment).Overlaps(frag) {
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if len(fq) < 1 {
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break OUTER
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}
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candidate = heap.Pop(&fq)
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continue OUTER
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2014-06-26 17:43:13 +02:00
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}
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}
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2014-07-11 20:25:32 +02:00
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bestFragments = append(bestFragments, candidate.(*Fragment))
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} else {
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bestFragments = append(bestFragments, candidate.(*Fragment))
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2014-06-26 17:43:13 +02:00
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}
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2014-07-11 20:25:32 +02:00
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if len(fq) < 1 {
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break
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}
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candidate = heap.Pop(&fq)
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2014-06-26 17:43:13 +02:00
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}
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}
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// now that we have the best fragments, we can format them
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formattedFragments := make([]string, len(bestFragments))
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for i, fragment := range bestFragments {
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2014-08-28 20:57:27 +02:00
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formattedFragments[i] = ""
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if fragment.start != 0 {
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formattedFragments[i] += s.sep
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}
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formattedFragments[i] += s.formatter.Format(fragment, dm.Locations[field])
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if fragment.end != len(fragment.orig) {
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formattedFragments[i] += s.sep
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}
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2014-06-26 17:43:13 +02:00
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}
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2014-07-03 20:53:44 +02:00
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if dm.Fragments == nil {
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dm.Fragments = make(FieldFragmentMap, 0)
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}
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dm.Fragments[field] = formattedFragments
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2014-06-26 17:43:13 +02:00
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return formattedFragments
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}
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// A PriorityQueue implements heap.Interface and holds Items.
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type FragmentQueue []*Fragment
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func (fq FragmentQueue) Len() int { return len(fq) }
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func (fq FragmentQueue) Less(i, j int) bool {
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// We want Pop to give us the highest, not lowest, priority so we use greater than here.
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return fq[i].score > fq[j].score
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}
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func (fq FragmentQueue) Swap(i, j int) {
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fq[i], fq[j] = fq[j], fq[i]
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fq[i].index = i
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fq[j].index = j
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}
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func (fq *FragmentQueue) Push(x interface{}) {
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n := len(*fq)
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item := x.(*Fragment)
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item.index = n
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*fq = append(*fq, item)
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}
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func (fq *FragmentQueue) Pop() interface{} {
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old := *fq
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n := len(old)
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item := old[n-1]
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item.index = -1 // for safety
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*fq = old[0 : n-1]
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return item
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}
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