88 lines
2.3 KiB
Go
88 lines
2.3 KiB
Go
// 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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package upside_down
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import (
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"bytes"
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"fmt"
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"github.com/couchbaselabs/bleve/index"
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"github.com/couchbaselabs/bleve/index/store"
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)
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type UpsideDownCouchFieldReader struct {
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index *UpsideDownCouch
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iterator store.KVIterator
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endKey []byte
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field uint16
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}
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func newUpsideDownCouchFieldReader(index *UpsideDownCouch, field uint16, startTerm, endTerm []byte) (*UpsideDownCouchFieldReader, error) {
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startRow := NewTermFrequencyRow(startTerm, field, "", 0, 0)
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startKey := startRow.ScanPrefixForFieldTermPrefix()
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endKey := NewTermFrequencyRow(endTerm, field, "", 0, 0).Key()
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it := index.store.Iterator(startKey)
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return &UpsideDownCouchFieldReader{
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index: index,
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iterator: it,
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field: field,
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endKey: endKey,
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}, nil
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}
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func (r *UpsideDownCouchFieldReader) Next() (*index.TermFieldDoc, error) {
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key, val, valid := r.iterator.Current()
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if !valid {
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return nil, nil
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}
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// past end term
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if bytes.Compare(key, r.endKey) > 0 {
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return nil, nil
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}
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currRow, err := NewTermFrequencyRowKV(key, val)
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if err != nil {
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return nil, fmt.Errorf("unexpected error parsing term freq row kv: %v", err)
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}
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rv := index.TermFieldDoc{
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Term: string(currRow.term),
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Freq: currRow.freq,
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}
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// advance the iterator to the next term
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// by using invalid doc id (higher sorting)
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nextTerm := incrementBytes(currRow.term)
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nextRow := NewTermFrequencyRow(nextTerm, r.field, "", 0, 0)
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r.iterator.Seek(nextRow.ScanPrefixForFieldTermPrefix())
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return &rv, nil
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}
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func (r *UpsideDownCouchFieldReader) Close() {
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r.iterator.Close()
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}
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func incrementBytes(in []byte) []byte {
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rv := make([]byte, len(in))
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copy(rv, in)
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for i := len(rv) - 1; i >= 0; i-- {
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rv[i] = rv[i] + 1
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if rv[i] != 0 {
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// didnt' overflow, so stop
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break
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}
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}
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return rv
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}
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