func NewTermPrefixSearcher(indexReader index.IndexReader, prefix string, field string, boost float64, explain bool) (*TermPrefixSearcher, error) {
// find the terms with this prefix
fieldDict, err := indexReader.FieldDictPrefix(field, []byte(prefix))
// enumerate all the terms in the range
qsearchers := make([]search.Searcher, 0, 25)
tfd, err := fieldDict.Next()
for err == nil && tfd != nil {
qsearcher, err := NewTermSearcher(indexReader, string(tfd.Term), field, 1.0, explain)
if err != nil {
return nil, err
}
qsearchers = append(qsearchers, qsearcher)
tfd, err = fieldDict.Next()
}
// build disjunction searcher of these ranges
searcher, err := NewDisjunctionSearcher(indexReader, qsearchers, 0, explain)
if err != nil {
return nil, err
}
return &TermPrefixSearcher{
indexReader: indexReader,
prefix: prefix,
field: field,
explain: explain,
searcher: searcher,
}, nil
}
func NewFuzzySearcher(indexReader index.IndexReader, term string, prefix, fuzziness int, field string, boost float64, explain bool) (*FuzzySearcher, error) {
prefixTerm := ""
for i, r := range term {
if i < prefix {
prefixTerm += string(r)
}
}
// find the terms with this prefix
var fieldDict index.FieldDict
var err error
if len(prefixTerm) > 0 {
fieldDict, err = indexReader.FieldDictPrefix(field, []byte(prefixTerm))
} else {
fieldDict, err = indexReader.FieldDict(field)
}
// enumerate terms and check levenshtein distance
candidateTerms := make([]string, 0)
tfd, err := fieldDict.Next()
for err == nil && tfd != nil {
ld, exceeded := search.LevenshteinDistanceMax(&term, &tfd.Term, fuzziness)
if !exceeded && ld <= fuzziness {
candidateTerms = append(candidateTerms, tfd.Term)
}
tfd, err = fieldDict.Next()
}
if err != nil {
return nil, err
}
// enumerate all the terms in the range
qsearchers := make([]search.Searcher, 0, 25)
for _, cterm := range candidateTerms {
qsearcher, err := NewTermSearcher(indexReader, cterm, field, 1.0, explain)
if err != nil {
return nil, err
}
qsearchers = append(qsearchers, qsearcher)
}
// build disjunction searcher of these ranges
searcher, err := NewDisjunctionSearcher(indexReader, qsearchers, 0, explain)
if err != nil {
return nil, err
}
return &FuzzySearcher{
indexReader: indexReader,
term: term,
prefix: prefix,
fuzziness: fuzziness,
field: field,
explain: explain,
searcher: searcher,
}, nil
}
func NewRegexpSearcher(indexReader index.IndexReader, pattern *regexp.Regexp, field string, boost float64, explain bool) (*RegexpSearcher, error) {
prefixTerm, complete := pattern.LiteralPrefix()
candidateTerms := make([]string, 0)
if complete {
// there is no pattern
candidateTerms = append(candidateTerms, prefixTerm)
} else {
var fieldDict index.FieldDict
var err error
if len(prefixTerm) > 0 {
fieldDict, err = indexReader.FieldDictPrefix(field, []byte(prefixTerm))
} else {
fieldDict, err = indexReader.FieldDict(field)
}
// enumerate the terms and check against regexp
tfd, err := fieldDict.Next()
for err == nil && tfd != nil {
if pattern.MatchString(tfd.Term) {
candidateTerms = append(candidateTerms, tfd.Term)
}
tfd, err = fieldDict.Next()
}
if err != nil {
return nil, err
}
}
// enumerate all the terms in the range
qsearchers := make([]search.Searcher, 0, 25)
for _, cterm := range candidateTerms {
qsearcher, err := NewTermSearcher(indexReader, cterm, field, 1.0, explain)
if err != nil {
return nil, err
}
qsearchers = append(qsearchers, qsearcher)
}
// build disjunction searcher of these ranges
searcher, err := NewDisjunctionSearcher(indexReader, qsearchers, 0, explain)
if err != nil {
return nil, err
}
return &RegexpSearcher{
indexReader: indexReader,
pattern: pattern,
field: field,
explain: explain,
searcher: searcher,
}, nil
}
func NewMatchAllSearcher(indexReader index.IndexReader, boost float64, explain bool) (*MatchAllSearcher, error) {
reader, err := indexReader.DocIDReader("", "")
if err != nil {
return nil, err
}
scorer := scorers.NewConstantScorer(1.0, boost, explain)
return &MatchAllSearcher{
indexReader: indexReader,
reader: reader,
scorer: scorer,
}, nil
}
func NewTermSearcher(indexReader index.IndexReader, term string, field string, boost float64, explain bool) (*TermSearcher, error) {
reader, err := indexReader.TermFieldReader([]byte(term), field)
if err != nil {
return nil, err
}
scorer := scorers.NewTermQueryScorer(term, field, boost, indexReader.DocCount(), reader.Count(), explain)
return &TermSearcher{
indexReader: indexReader,
term: term,
field: field,
explain: explain,
reader: reader,
scorer: scorer,
}, nil
}
func NewDocIDSearcher(indexReader index.IndexReader, ids []string, boost float64,
explain bool) (searcher *DocIDSearcher, err error) {
kept := make([]string, len(ids))
copy(kept, ids)
sort.Strings(kept)
if len(ids) > 0 {
var idReader index.DocIDReader
endTerm := string(incrementBytes([]byte(kept[len(kept)-1])))
idReader, err = indexReader.DocIDReader(kept[0], endTerm)
if err != nil {
return nil, err
}
defer func() {
if cerr := idReader.Close(); err == nil && cerr != nil {
err = cerr
}
}()
j := 0
for _, id := range kept {
doc, err := idReader.Advance(id)
if err != nil {
return nil, err
}
// Non-duplicate match
if doc == id && (j == 0 || kept[j-1] != id) {
kept[j] = id
j++
}
}
kept = kept[:j]
}
scorer := scorers.NewConstantScorer(1.0, boost, explain)
return &DocIDSearcher{
ids: kept,
scorer: scorer,
}, nil
}