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104 lines
2.9 KiB
104 lines
2.9 KiB
// Copyright (c) 2017 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 mem
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import (
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"sort"
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"strings"
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"github.com/RoaringBitmap/roaring"
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"github.com/blevesearch/bleve/index"
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"github.com/blevesearch/bleve/index/scorch/segment"
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)
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// Dictionary is the in-memory representation of the term dictionary
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type Dictionary struct {
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segment *Segment
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field string
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fieldID uint16
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}
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// PostingsList returns the postings list for the specified term
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func (d *Dictionary) PostingsList(term string,
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except *roaring.Bitmap) (segment.PostingsList, error) {
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return &PostingsList{
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dictionary: d,
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term: term,
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postingsID: d.segment.Dicts[d.fieldID][term],
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except: except,
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}, nil
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}
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// Iterator returns an iterator for this dictionary
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func (d *Dictionary) Iterator() segment.DictionaryIterator {
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return &DictionaryIterator{
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d: d,
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}
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}
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// PrefixIterator returns an iterator which only visits terms having the
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// the specified prefix
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func (d *Dictionary) PrefixIterator(prefix string) segment.DictionaryIterator {
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offset := sort.SearchStrings(d.segment.DictKeys[d.fieldID], prefix)
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return &DictionaryIterator{
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d: d,
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prefix: prefix,
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offset: offset,
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}
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}
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// RangeIterator returns an iterator which only visits terms between the
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// start and end terms. NOTE: bleve.index API specifies the end is inclusive.
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func (d *Dictionary) RangeIterator(start, end string) segment.DictionaryIterator {
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offset := sort.SearchStrings(d.segment.DictKeys[d.fieldID], start)
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return &DictionaryIterator{
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d: d,
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offset: offset,
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end: end,
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}
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}
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// DictionaryIterator is an iterator for term dictionary
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type DictionaryIterator struct {
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d *Dictionary
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prefix string
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end string
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offset int
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dictEntry index.DictEntry // reused across Next()'s
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}
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// Next returns the next entry in the dictionary
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func (d *DictionaryIterator) Next() (*index.DictEntry, error) {
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if d.offset > len(d.d.segment.DictKeys[d.d.fieldID])-1 {
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return nil, nil
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}
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next := d.d.segment.DictKeys[d.d.fieldID][d.offset]
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// check prefix
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if d.prefix != "" && !strings.HasPrefix(next, d.prefix) {
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return nil, nil
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}
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// check end (bleve.index API demands inclusive end)
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if d.end != "" && next > d.end {
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return nil, nil
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}
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d.offset++
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postingID := d.d.segment.Dicts[d.d.fieldID][next]
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d.dictEntry.Term = next
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d.dictEntry.Count = d.d.segment.Postings[postingID-1].GetCardinality()
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return &d.dictEntry, nil
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}
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