forked from blevesearch/bleve
/
search_phrase.go
437 lines (383 loc) · 11.9 KB
/
search_phrase.go
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// Copyright (c) 2014 Couchbase, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package searcher
import (
"fmt"
"math"
"reflect"
"github.com/blevesearch/bleve/index"
"github.com/blevesearch/bleve/search"
"github.com/blevesearch/bleve/size"
)
var reflectStaticSizePhraseSearcher int
func init() {
var ps PhraseSearcher
reflectStaticSizePhraseSearcher = int(reflect.TypeOf(ps).Size())
}
type PhraseSearcher struct {
mustSearcher search.Searcher
queryNorm float64
currMust *search.DocumentMatch
terms [][]string
path phrasePath
paths []phrasePath
locations []search.Location
initialized bool
}
func (s *PhraseSearcher) Size() int {
sizeInBytes := reflectStaticSizePhraseSearcher + size.SizeOfPtr
if s.mustSearcher != nil {
sizeInBytes += s.mustSearcher.Size()
}
if s.currMust != nil {
sizeInBytes += s.currMust.Size()
}
for _, entry := range s.terms {
sizeInBytes += size.SizeOfSlice
for _, entry1 := range entry {
sizeInBytes += size.SizeOfString + len(entry1)
}
}
return sizeInBytes
}
func NewPhraseSearcher(indexReader index.IndexReader, terms []string, field string, options search.SearcherOptions) (*PhraseSearcher, error) {
// turn flat terms []string into [][]string
mterms := make([][]string, len(terms))
for i, term := range terms {
mterms[i] = []string{term}
}
return NewMultiPhraseSearcher(indexReader, mterms, field, options)
}
func NewMultiPhraseSearcher(indexReader index.IndexReader, terms [][]string, field string, options search.SearcherOptions) (*PhraseSearcher, error) {
options.IncludeTermVectors = true
var termPositionSearchers []search.Searcher
for _, termPos := range terms {
if len(termPos) == 1 && termPos[0] != "" {
// single term
ts, err := NewTermSearcher(indexReader, termPos[0], field, 1.0, options)
if err != nil {
// close any searchers already opened
for _, ts := range termPositionSearchers {
_ = ts.Close()
}
return nil, fmt.Errorf("phrase searcher error building term searcher: %v", err)
}
termPositionSearchers = append(termPositionSearchers, ts)
} else if len(termPos) > 1 {
// multiple terms
var termSearchers []search.Searcher
for _, term := range termPos {
if term == "" {
continue
}
ts, err := NewTermSearcher(indexReader, term, field, 1.0, options)
if err != nil {
// close any searchers already opened
for _, ts := range termPositionSearchers {
_ = ts.Close()
}
return nil, fmt.Errorf("phrase searcher error building term searcher: %v", err)
}
termSearchers = append(termSearchers, ts)
}
disjunction, err := NewDisjunctionSearcher(indexReader, termSearchers, 1, options)
if err != nil {
// close any searchers already opened
for _, ts := range termPositionSearchers {
_ = ts.Close()
}
return nil, fmt.Errorf("phrase searcher error building term position disjunction searcher: %v", err)
}
termPositionSearchers = append(termPositionSearchers, disjunction)
}
}
mustSearcher, err := NewConjunctionSearcher(indexReader, termPositionSearchers, options)
if err != nil {
// close any searchers already opened
for _, ts := range termPositionSearchers {
_ = ts.Close()
}
return nil, fmt.Errorf("phrase searcher error building conjunction searcher: %v", err)
}
// build our searcher
rv := PhraseSearcher{
mustSearcher: mustSearcher,
terms: terms,
}
rv.computeQueryNorm()
return &rv, nil
}
func (s *PhraseSearcher) computeQueryNorm() {
// first calculate sum of squared weights
sumOfSquaredWeights := 0.0
if s.mustSearcher != nil {
sumOfSquaredWeights += s.mustSearcher.Weight()
}
// now compute query norm from this
s.queryNorm = 1.0 / math.Sqrt(sumOfSquaredWeights)
// finally tell all the downstream searchers the norm
if s.mustSearcher != nil {
s.mustSearcher.SetQueryNorm(s.queryNorm)
}
}
func (s *PhraseSearcher) initSearchers(ctx *search.SearchContext) error {
err := s.advanceNextMust(ctx)
if err != nil {
return err
}
s.initialized = true
return nil
}
func (s *PhraseSearcher) advanceNextMust(ctx *search.SearchContext) error {
var err error
if s.mustSearcher != nil {
if s.currMust != nil {
ctx.DocumentMatchPool.Put(s.currMust)
}
s.currMust, err = s.mustSearcher.Next(ctx)
if err != nil {
return err
}
}
return nil
}
func (s *PhraseSearcher) Weight() float64 {
return s.mustSearcher.Weight()
}
func (s *PhraseSearcher) SetQueryNorm(qnorm float64) {
s.mustSearcher.SetQueryNorm(qnorm)
}
func (s *PhraseSearcher) Next(ctx *search.SearchContext) (*search.DocumentMatch, error) {
if !s.initialized {
err := s.initSearchers(ctx)
if err != nil {
return nil, err
}
}
for s.currMust != nil {
// check this match against phrase constraints
rv := s.checkCurrMustMatch(ctx)
// prepare for next iteration (either loop or subsequent call to Next())
err := s.advanceNextMust(ctx)
if err != nil {
return nil, err
}
// if match satisfied phrase constraints return it as a hit
if rv != nil {
return rv, nil
}
}
return nil, nil
}
// checkCurrMustMatch is solely concerned with determining if the DocumentMatch
// pointed to by s.currMust (which satisifies the pre-condition searcher)
// also satisfies the phase constraints. if so, it returns a DocumentMatch
// for this document, otherwise nil
func (s *PhraseSearcher) checkCurrMustMatch(ctx *search.SearchContext) *search.DocumentMatch {
s.locations = s.currMust.Complete(s.locations)
locations := s.currMust.Locations
s.currMust.Locations = nil
ftls := s.currMust.FieldTermLocations
// typically we would expect there to only actually be results in
// one field, but we allow for this to not be the case
// but, we note that phrase constraints can only be satisfied within
// a single field, so we can check them each independently
for field, tlm := range locations {
ftls = s.checkCurrMustMatchField(ctx, field, tlm, ftls)
}
if len(ftls) > 0 {
// return match
rv := s.currMust
s.currMust = nil
rv.FieldTermLocations = ftls
return rv
}
return nil
}
// checkCurrMustMatchField is solely concerned with determining if one
// particular field within the currMust DocumentMatch Locations
// satisfies the phase constraints (possibly more than once). if so,
// the matching field term locations are appended to the provided
// slice
func (s *PhraseSearcher) checkCurrMustMatchField(ctx *search.SearchContext,
field string, tlm search.TermLocationMap,
ftls []search.FieldTermLocation) []search.FieldTermLocation {
if s.path == nil {
s.path = make(phrasePath, 0, len(s.terms))
}
s.paths = findPhrasePaths(0, nil, s.terms, tlm, s.path[:0], 0, s.paths[:0])
for _, p := range s.paths {
for _, pp := range p {
ftls = append(ftls, search.FieldTermLocation{
Field: field,
Term: pp.term,
Location: search.Location{
Pos: pp.loc.Pos,
Start: pp.loc.Start,
End: pp.loc.End,
ArrayPositions: pp.loc.ArrayPositions,
},
})
}
}
return ftls
}
type phrasePart struct {
term string
loc *search.Location
}
func (p *phrasePart) String() string {
return fmt.Sprintf("[%s %v]", p.term, p.loc)
}
type phrasePath []phrasePart
func (p phrasePath) MergeInto(in search.TermLocationMap) {
for _, pp := range p {
in[pp.term] = append(in[pp.term], pp.loc)
}
}
func (p phrasePath) String() string {
rv := "["
for i, pp := range p {
if i > 0 {
rv += ", "
}
rv += pp.String()
}
rv += "]"
return rv
}
// findPhrasePaths is a function to identify phase matches from a set
// of known term locations. it recursive so care must be taken with
// arguments and return values.
//
// prevPos - the previous location, 0 on first invocation
// ap - array positions of the first candidate phrase part to
// which further recursive phrase parts must match,
// nil on initial invocation or when there are no array positions
// phraseTerms - slice containing the phrase terms,
// may contain empty string as placeholder (don't care)
// tlm - the Term Location Map containing all relevant term locations
// p - the current path being explored (appended to in recursive calls)
// this is the primary state being built during the traversal
// remainingSlop - amount of sloppiness that's allowed, which is the
// sum of the editDistances from each matching phrase part,
// where 0 means no sloppiness allowed (all editDistances must be 0),
// decremented during recursion
// rv - the final result being appended to by all the recursive calls
//
// returns slice of paths, or nil if invocation did not find any successul paths
func findPhrasePaths(prevPos uint64, ap search.ArrayPositions, phraseTerms [][]string,
tlm search.TermLocationMap, p phrasePath, remainingSlop int, rv []phrasePath) []phrasePath {
// no more terms
if len(phraseTerms) < 1 {
// snapshot or copy the recursively built phrasePath p and
// append it to the rv, also optimizing by checking if next
// phrasePath item in the rv (which we're about to overwrite)
// is available for reuse
var pcopy phrasePath
if len(rv) < cap(rv) {
pcopy = rv[:len(rv)+1][len(rv)][:0]
}
return append(rv, append(pcopy, p...))
}
car := phraseTerms[0]
cdr := phraseTerms[1:]
// empty term is treated as match (continue)
if len(car) == 0 || (len(car) == 1 && car[0] == "") {
nextPos := prevPos + 1
if prevPos == 0 {
// if prevPos was 0, don't set it to 1 (as thats not a real abs pos)
nextPos = 0 // don't advance nextPos if prevPos was 0
}
return findPhrasePaths(nextPos, ap, cdr, tlm, p, remainingSlop, rv)
}
// locations for this term
for _, carTerm := range car {
locations := tlm[carTerm]
LOCATIONS_LOOP:
for _, loc := range locations {
if prevPos != 0 && !loc.ArrayPositions.Equals(ap) {
// if the array positions are wrong, can't match, try next location
continue
}
// compute distance from previous phrase term
dist := 0
if prevPos != 0 {
dist = editDistance(prevPos+1, loc.Pos)
}
// if enough slop remaining, continue recursively
if prevPos == 0 || (remainingSlop-dist) >= 0 {
// skip if we've already used this term+loc already
for _, ppart := range p {
if ppart.term == carTerm && ppart.loc == loc {
continue LOCATIONS_LOOP
}
}
// this location works, add it to the path (but not for empty term)
px := append(p, phrasePart{term: carTerm, loc: loc})
rv = findPhrasePaths(loc.Pos, loc.ArrayPositions, cdr, tlm, px, remainingSlop-dist, rv)
}
}
}
return rv
}
func editDistance(p1, p2 uint64) int {
dist := int(p1 - p2)
if dist < 0 {
return -dist
}
return dist
}
func (s *PhraseSearcher) Advance(ctx *search.SearchContext, ID index.IndexInternalID) (*search.DocumentMatch, error) {
if !s.initialized {
err := s.initSearchers(ctx)
if err != nil {
return nil, err
}
}
if s.currMust != nil {
if s.currMust.IndexInternalID.Compare(ID) >= 0 {
return s.Next(ctx)
}
ctx.DocumentMatchPool.Put(s.currMust)
}
if s.currMust == nil {
return nil, nil
}
var err error
s.currMust, err = s.mustSearcher.Advance(ctx, ID)
if err != nil {
return nil, err
}
return s.Next(ctx)
}
func (s *PhraseSearcher) Count() uint64 {
// for now return a worst case
return s.mustSearcher.Count()
}
func (s *PhraseSearcher) Close() error {
if s.mustSearcher != nil {
err := s.mustSearcher.Close()
if err != nil {
return err
}
}
return nil
}
func (s *PhraseSearcher) Min() int {
return 0
}
func (s *PhraseSearcher) DocumentMatchPoolSize() int {
return s.mustSearcher.DocumentMatchPoolSize() + 1
}