2017-12-09 20:28:33 +01:00
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// 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 zap
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import (
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"fmt"
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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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2017-12-19 19:49:57 +01:00
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"github.com/couchbase/vellum"
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"github.com/couchbase/vellum/regexp"
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2017-12-09 20:28:33 +01:00
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)
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// Dictionary is the zap representation of the term dictionary
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type Dictionary struct {
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2018-01-18 03:46:57 +01:00
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sb *SegmentBase
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2017-12-09 20:28:33 +01:00
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field string
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fieldID uint16
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fst *vellum.FST
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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, except *roaring.Bitmap) (segment.PostingsList, error) {
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2018-02-07 23:29:51 +01:00
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return d.postingsList([]byte(term), except, nil)
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2017-12-09 20:28:33 +01:00
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}
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2018-02-07 23:29:51 +01:00
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func (d *Dictionary) postingsList(term []byte, except *roaring.Bitmap, rv *PostingsList) (*PostingsList, error) {
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2018-02-13 02:47:28 +01:00
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if d.fst == nil {
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return d.postingsListInit(rv, except), nil
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}
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postingsOffset, exists, err := d.fst.Get(term)
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if err != nil {
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return nil, fmt.Errorf("vellum err: %v", err)
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}
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if !exists {
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return d.postingsListInit(rv, except), nil
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}
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return d.postingsListFromOffset(postingsOffset, except, rv)
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}
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func (d *Dictionary) postingsListFromOffset(postingsOffset uint64, except *roaring.Bitmap, rv *PostingsList) (*PostingsList, error) {
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rv = d.postingsListInit(rv, except)
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err := rv.read(postingsOffset, d)
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if err != nil {
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return nil, err
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}
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return rv, nil
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}
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func (d *Dictionary) postingsListInit(rv *PostingsList, except *roaring.Bitmap) *PostingsList {
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if rv == nil {
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rv = &PostingsList{}
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} else {
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2018-03-12 04:13:31 +01:00
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postings := rv.postings
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if postings != nil {
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postings.Clear()
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}
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locBitmap := rv.locBitmap
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if locBitmap != nil {
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locBitmap.Clear()
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}
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2018-02-07 23:29:51 +01:00
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*rv = PostingsList{} // clear the struct
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2018-03-12 04:13:31 +01:00
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rv.postings = postings
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rv.locBitmap = locBitmap
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2017-12-09 20:28:33 +01:00
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}
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2018-02-07 23:29:51 +01:00
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rv.sb = d.sb
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rv.except = except
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return rv
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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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rv := &DictionaryIterator{
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d: d,
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}
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if d.fst != nil {
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itr, err := d.fst.Iterator(nil, nil)
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if err == nil {
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rv.itr = itr
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}
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}
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return rv
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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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rv := &DictionaryIterator{
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d: d,
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}
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if d.fst != nil {
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r, err := regexp.New(prefix + ".*")
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if err == nil {
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itr, err := d.fst.Search(r, nil, nil)
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if err == nil {
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rv.itr = itr
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}
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}
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}
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return rv
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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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rv := &DictionaryIterator{
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d: d,
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}
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// need to increment the end position to be inclusive
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endBytes := []byte(end)
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if endBytes[len(endBytes)-1] < 0xff {
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endBytes[len(endBytes)-1]++
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} else {
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endBytes = append(endBytes, 0xff)
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}
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if d.fst != nil {
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itr, err := d.fst.Iterator([]byte(start), endBytes)
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if err == nil {
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rv.itr = itr
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}
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}
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return rv
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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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itr vellum.Iterator
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err error
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2018-01-30 19:27:07 +01:00
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tmp PostingsList
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2017-12-09 20:28:33 +01:00
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}
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// Next returns the next entry in the dictionary
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func (i *DictionaryIterator) Next() (*index.DictEntry, error) {
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if i.itr == nil || i.err == vellum.ErrIteratorDone {
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return nil, nil
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} else if i.err != nil {
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return nil, i.err
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}
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2018-01-30 19:27:07 +01:00
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term, postingsOffset := i.itr.Current()
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i.err = i.tmp.read(postingsOffset, i.d)
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if i.err != nil {
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return nil, i.err
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}
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rv := &index.DictEntry{
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Term: string(term),
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Count: i.tmp.Count(),
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2017-12-09 20:28:33 +01:00
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}
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i.err = i.itr.Next()
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return rv, nil
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}
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