/
splitter.go
139 lines (130 loc) · 3.45 KB
/
splitter.go
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// Copyright 2015 ikawaha
//
// 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 splitter
import (
"unicode"
"unicode/utf8"
)
// SentenceSplitter is a tiny sentence splitter for japanese texts.
type SentenceSplitter struct {
Delim []rune // delimiter set. ex. {'。','.'}
Follower []rune // allow following after delimiters. ex. {'」','』'}
SkipWhiteSpace bool // eliminate white space or not
DoubleLineFeedSplit bool // splite at '\n\n' or not
MaxRuneLen int // max sentence length
}
var (
// default sentence splitter
defaultSplitter = &SentenceSplitter{
Delim: []rune{'。', '.', '!', '!', '?', '?'},
Follower: []rune{'.', '」', '」', '』', ')', ')', '}', '}', '〉', '》'},
SkipWhiteSpace: true,
DoubleLineFeedSplit: true,
MaxRuneLen: 256,
}
)
// ScanSentences is a split function for a bufio.Scanner that returns each sentence of text.
func ScanSentences(data []byte, atEOF bool) (advance int, token []byte, err error) {
return defaultSplitter.ScanSentences(data, atEOF)
}
func (s SentenceSplitter) isDelim(r rune) bool {
for _, d := range s.Delim {
if r == d {
return true
}
}
return false
}
func (s SentenceSplitter) isFollower(r rune) bool {
for _, d := range s.Follower {
if r == d {
return true
}
}
return false
}
// ScanSentences is a split function for a Scanner that returns each sentence of text.
func (s SentenceSplitter) ScanSentences(data []byte, atEOF bool) (advance int, token []byte, err error) {
if atEOF && len(data) == 0 {
return 0, nil, nil
}
var (
start, end, rcount int
head, nn bool
)
head = true
for p := 0; p < len(data); {
r, size := utf8.DecodeRune(data[p:])
if s.SkipWhiteSpace && unicode.IsSpace(r) {
p += size
if head {
start, end = p, p
} else if s.isDelim(r) {
return p, data[start:end], nil
} else if s.DoubleLineFeedSplit && r == '\n' {
if nn {
return p, data[start:end], nil
}
nn = true
}
continue
}
head, nn = false, false // clear flags
if end != p {
for i := 0; i < size; i++ {
data[end+i] = data[p+i]
}
}
p += size
end += size
rcount++
if !s.isDelim(r) && rcount < s.MaxRuneLen {
continue
}
// split
nn = false
for p < len(data) {
r, size := utf8.DecodeRune(data[p:])
if s.SkipWhiteSpace && unicode.IsSpace(r) {
p += size
if s.DoubleLineFeedSplit && r == '\n' {
if nn {
return p, data[start:end], nil
}
nn = true
}
} else if s.isDelim(r) || s.isFollower(r) {
if end != p {
for i := 0; i < size; i++ {
data[end+i] = data[p+i]
}
}
p += size
end += size
} else {
break
}
}
return p, data[start:end], nil
}
if !atEOF {
// Request more data
for i := end; i < len(data); i++ {
data[i] = ' '
}
return start, nil, nil
}
// If we're at EOF, we have a final, non-terminated line. Return it.
return len(data), data[start:end], nil
}