175 lines
4.3 KiB
Go
175 lines
4.3 KiB
Go
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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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package search
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import (
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"math"
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"sort"
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"github.com/couchbaselabs/bleve/index"
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)
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type TermDisjunctionSearcher struct {
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index index.Index
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searchers OrderedSearcherList
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queryNorm float64
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currs []*DocumentMatch
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currentId string
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scorer *TermDisjunctionQueryScorer
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min float64
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}
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func NewTermDisjunctionSearcher(index index.Index, query *TermDisjunctionQuery) (*TermDisjunctionSearcher, error) {
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// build the downstream searchres
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searchers := make(OrderedSearcherList, len(query.Terms))
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for i, termQuery := range query.Terms {
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searcher, err := termQuery.Searcher(index)
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if err != nil {
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return nil, err
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}
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searchers[i] = searcher
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}
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// sort the searchers
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sort.Sort(sort.Reverse(searchers))
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// build our searcher
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rv := TermDisjunctionSearcher{
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index: index,
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searchers: searchers,
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currs: make([]*DocumentMatch, len(searchers)),
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scorer: NewTermDisjunctionQueryScorer(query.Explain),
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min: query.Min,
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}
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rv.computeQueryNorm()
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err := rv.initSearchers()
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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 (s *TermDisjunctionSearcher) computeQueryNorm() {
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// first calculate sum of squared weights
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sumOfSquaredWeights := 0.0
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for _, termSearcher := range s.searchers {
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sumOfSquaredWeights += termSearcher.Weight()
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}
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// now compute query norm from this
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s.queryNorm = 1.0 / math.Sqrt(sumOfSquaredWeights)
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// finally tell all the downsteam searchers the norm
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for _, termSearcher := range s.searchers {
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termSearcher.SetQueryNorm(s.queryNorm)
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}
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}
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func (s *TermDisjunctionSearcher) initSearchers() error {
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var err error
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// get all searchers pointing at their first match
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for i, termSearcher := range s.searchers {
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s.currs[i], err = termSearcher.Next()
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if err != nil {
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return err
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}
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}
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s.currentId = s.nextSmallestId()
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return nil
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}
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func (s *TermDisjunctionSearcher) nextSmallestId() string {
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rv := ""
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for _, curr := range s.currs {
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if curr != nil && (curr.ID < rv || rv == "") {
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rv = curr.ID
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}
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}
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return rv
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}
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func (s *TermDisjunctionSearcher) Weight() float64 {
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var rv float64
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for _, searcher := range s.searchers {
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rv += searcher.Weight()
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}
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return rv
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}
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func (s *TermDisjunctionSearcher) SetQueryNorm(qnorm float64) {
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for _, searcher := range s.searchers {
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searcher.SetQueryNorm(qnorm)
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}
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}
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func (s *TermDisjunctionSearcher) Next() (*DocumentMatch, error) {
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var err error
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var rv *DocumentMatch
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matching := make([]*DocumentMatch, 0)
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found := false
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for !found && s.currentId != "" {
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for _, curr := range s.currs {
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if curr != nil && curr.ID == s.currentId {
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matching = append(matching, curr)
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}
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}
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if len(matching) >= int(s.min) {
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found = true
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// score this match
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rv = s.scorer.Score(matching, len(matching), len(s.searchers))
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}
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// reset matching
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matching = make([]*DocumentMatch, 0)
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// invoke next on all the matching searchers
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for i, curr := range s.currs {
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if curr != nil && curr.ID == s.currentId {
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searcher := s.searchers[i]
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s.currs[i], err = searcher.Next()
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if err != nil {
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return nil, err
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}
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}
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}
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s.currentId = s.nextSmallestId()
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}
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return rv, nil
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}
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func (s *TermDisjunctionSearcher) Advance(ID string) (*DocumentMatch, error) {
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// get all searchers pointing at their first match
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var err error
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for i, termSearcher := range s.searchers {
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s.currs[i], err = termSearcher.Advance(ID)
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if err != nil {
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return nil, err
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}
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}
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s.currentId = s.nextSmallestId()
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return s.Next()
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}
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func (s *TermDisjunctionSearcher) Count() uint64 {
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// for now return a worst case
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var sum uint64 = 0
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for _, searcher := range s.searchers {
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sum += searcher.Count()
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}
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return sum
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}
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func (s *TermDisjunctionSearcher) Close() {
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for _, searcher := range s.searchers {
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searcher.Close()
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}
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}
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