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added ngram and edge ngram token filters

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closes #46 and closes #47
This commit is contained in:
Marty Schoch 2014-08-06 22:11:42 -04:00
parent 9a777aaa80
commit c19270108c
4 changed files with 429 additions and 0 deletions
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91
analysis/token_filters/edge_ngram_filter/edge_ngram_filter.go Normal file
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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 edge_ngram_filter
import (
"bytes"
"unicode/utf8"
"github.com/couchbaselabs/bleve/analysis"
)
type Side bool
const BACK Side = true
const FRONT Side = false
type EdgeNgramFilter struct {
back Side
minLength int
maxLength int
}
func NewEdgeNgramFilter(side Side, minLength, maxLength int) *EdgeNgramFilter {
return &EdgeNgramFilter{
back: side,
minLength: minLength,
maxLength: maxLength,
}
}
func (s *EdgeNgramFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
rv := make(analysis.TokenStream, 0)
for _, token := range input {
runeCount := utf8.RuneCount(token.Term)
runes := bytes.Runes(token.Term)
if s.back {
i := runeCount
// index of the starting rune for this token
for ngramSize := s.minLength; ngramSize <= s.maxLength; ngramSize++ {
// build an ngram of this size starting at i
if i-ngramSize > 0 {
ngramTerm := buildTermFromRunes(runes[i-ngramSize : i])
token := analysis.Token{
Position: token.Position,
Start: token.Start,
End: token.End,
Type: token.Type,
Term: ngramTerm,
}
rv = append(rv, &token)
}
}
} else {
i := 0
// index of the starting rune for this token
for ngramSize := s.minLength; ngramSize <= s.maxLength; ngramSize++ {
// build an ngram of this size starting at i
if i+ngramSize <= runeCount {
ngramTerm := buildTermFromRunes(runes[i : i+ngramSize])
token := analysis.Token{
Position: token.Position,
Start: token.Start,
End: token.End,
Type: token.Type,
Term: ngramTerm,
}
rv = append(rv, &token)
}
}
}
}
return rv
}
func buildTermFromRunes(runes []rune) []byte {
rv := make([]byte, 0, len(runes)*4)
for _, r := range runes {
runeBytes := make([]byte, utf8.RuneLen(r))
utf8.EncodeRune(runeBytes, r)
rv = append(rv, runeBytes...)
}
return rv
}

141
analysis/token_filters/edge_ngram_filter/edge_ngram_filter_test.go Normal file
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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 edge_ngram_filter
import (
"reflect"
"testing"
"github.com/couchbaselabs/bleve/analysis"
)
func TestEdgeNgramFilter(t *testing.T) {
tests := []struct {
side Side
min int
max int
input analysis.TokenStream
output analysis.TokenStream
}{
{
side: FRONT,
min: 1,
max: 1,
input: analysis.TokenStream{
&analysis.Token{
Term: []byte("abcde"),
},
},
output: analysis.TokenStream{
&analysis.Token{
Term: []byte("a"),
},
},
},
{
side: BACK,
min: 1,
max: 1,
input: analysis.TokenStream{
&analysis.Token{
Term: []byte("abcde"),
},
},
output: analysis.TokenStream{
&analysis.Token{
Term: []byte("e"),
},
},
},
{
side: FRONT,
min: 1,
max: 3,
input: analysis.TokenStream{
&analysis.Token{
Term: []byte("abcde"),
},
},
output: analysis.TokenStream{
&analysis.Token{
Term: []byte("a"),
},
&analysis.Token{
Term: []byte("ab"),
},
&analysis.Token{
Term: []byte("abc"),
},
},
},
{
side: BACK,
min: 1,
max: 3,
input: analysis.TokenStream{
&analysis.Token{
Term: []byte("abcde"),
},
},
output: analysis.TokenStream{
&analysis.Token{
Term: []byte("e"),
},
&analysis.Token{
Term: []byte("de"),
},
&analysis.Token{
Term: []byte("cde"),
},
},
},
{
side: FRONT,
min: 1,
max: 3,
input: analysis.TokenStream{
&analysis.Token{
Term: []byte("abcde"),
},
&analysis.Token{
Term: []byte("vwxyz"),
},
},
output: analysis.TokenStream{
&analysis.Token{
Term: []byte("a"),
},
&analysis.Token{
Term: []byte("ab"),
},
&analysis.Token{
Term: []byte("abc"),
},
&analysis.Token{
Term: []byte("v"),
},
&analysis.Token{
Term: []byte("vw"),
},
&analysis.Token{
Term: []byte("vwx"),
},
},
},
}
for _, test := range tests {
edgeNgramFilter := NewEdgeNgramFilter(test.side, test.min, test.max)
actual := edgeNgramFilter.Filter(test.input)
if !reflect.DeepEqual(actual, test.output) {
t.Errorf("expected %s, got %s", test.output, actual)
}
}
}

66
analysis/token_filters/ngram_filter/ngram_filter.go Normal file
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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 ngram_filter
import (
"bytes"
"unicode/utf8"
"github.com/couchbaselabs/bleve/analysis"
)
type NgramFilter struct {
minLength int
maxLength int
}
func NewNgramFilter(minLength, maxLength int) *NgramFilter {
return &NgramFilter{
minLength: minLength,
maxLength: maxLength,
}
}
func (s *NgramFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
rv := make(analysis.TokenStream, 0)
for _, token := range input {
runeCount := utf8.RuneCount(token.Term)
runes := bytes.Runes(token.Term)
for i := 0; i < runeCount; i++ {
// index of the starting rune for this token
for ngramSize := s.minLength; ngramSize <= s.maxLength; ngramSize++ {
// build an ngram of this size starting at i
if i+ngramSize <= runeCount {
ngramTerm := buildTermFromRunes(runes[i : i+ngramSize])
token := analysis.Token{
Position: token.Position,
Start: token.Start,
End: token.End,
Type: token.Type,
Term: ngramTerm,
}
rv = append(rv, &token)
}
}
}
}
return rv
}
func buildTermFromRunes(runes []rune) []byte {
rv := make([]byte, 0, len(runes)*4)
for _, r := range runes {
runeBytes := make([]byte, utf8.RuneLen(r))
utf8.EncodeRune(runeBytes, r)
rv = append(rv, runeBytes...)
}
return rv
}

131
analysis/token_filters/ngram_filter/ngram_filter_test.go Normal file
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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 ngram_filter
import (
"reflect"
"testing"
"github.com/couchbaselabs/bleve/analysis"
)
func TestNgramFilter(t *testing.T) {
tests := []struct {
min int
max int
input analysis.TokenStream
output analysis.TokenStream
}{
{
min: 1,
max: 1,
input: analysis.TokenStream{
&analysis.Token{
Term: []byte("abcde"),
},
},
output: analysis.TokenStream{
&analysis.Token{
Term: []byte("a"),
},
&analysis.Token{
Term: []byte("b"),
},
&analysis.Token{
Term: []byte("c"),
},
&analysis.Token{
Term: []byte("d"),
},
&analysis.Token{
Term: []byte("e"),
},
},
},
{
min: 2,
max: 2,
input: analysis.TokenStream{
&analysis.Token{
Term: []byte("abcde"),
},
},
output: analysis.TokenStream{
&analysis.Token{
Term: []byte("ab"),
},
&analysis.Token{
Term: []byte("bc"),
},
&analysis.Token{
Term: []byte("cd"),
},
&analysis.Token{
Term: []byte("de"),
},
},
},
{
min: 1,
max: 3,
input: analysis.TokenStream{
&analysis.Token{
Term: []byte("abcde"),
},
},
output: analysis.TokenStream{
&analysis.Token{
Term: []byte("a"),
},
&analysis.Token{
Term: []byte("ab"),
},
&analysis.Token{
Term: []byte("abc"),
},
&analysis.Token{
Term: []byte("b"),
},
&analysis.Token{
Term: []byte("bc"),
},
&analysis.Token{
Term: []byte("bcd"),
},
&analysis.Token{
Term: []byte("c"),
},
&analysis.Token{
Term: []byte("cd"),
},
&analysis.Token{
Term: []byte("cde"),
},
&analysis.Token{
Term: []byte("d"),
},
&analysis.Token{
Term: []byte("de"),
},
&analysis.Token{
Term: []byte("e"),
},
},
},
}
for _, test := range tests {
ngramFilter := NewNgramFilter(test.min, test.max)
actual := ngramFilter.Filter(test.input)
if !reflect.DeepEqual(actual, test.output) {
t.Errorf("expected %s, got %s", test.output, actual)
}
}
}