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wordpieceTokenizer.go
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/
wordpieceTokenizer.go
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package go_bert_tokenizer
import (
"strings"
)
const DefaultMaxWordChars = 200
const DefaultUnknownToken = "[UNK]"
type WordpieceTokenizer struct {
Vocab *Vocab
MaxWordChars int
UnknownToken string
}
func NewWordpieceTokenizer(voc *Vocab) *WordpieceTokenizer {
return &WordpieceTokenizer{
Vocab: voc,
MaxWordChars: DefaultMaxWordChars,
UnknownToken: DefaultUnknownToken,
}
}
func (tkz *WordpieceTokenizer) Tokenize(text string) []string {
var toks []string
for _, tok := range tokenizeWhitespace(text) {
char := strings.Split(tok, "")
if len(char) > tkz.MaxWordChars {
toks = append(toks, tkz.UnknownToken)
continue
}
isBad := false
start := 0
sub_tokens := []string{}
for start < len(char) {
end := len(char)
curSubStr := ""
for start < end {
substr := strings.Join(char[start:end], "")
if start > 0 {
substr = "##" + substr
}
if _, ok := tkz.Vocab.GetToken()[substr]; ok {
curSubStr = substr
break
}
end -= 1
}
if curSubStr == "" {
isBad = true
break
}
sub_tokens = append(sub_tokens, curSubStr)
start = end
}
if isBad {
toks = append(toks, tkz.UnknownToken)
} else {
toks = append(toks, sub_tokens...)
}
}
return toks
}
func (tkz *WordpieceTokenizer) SetMaxWordChars(c int) {
tkz.MaxWordChars = c
}
func (tkz *WordpieceTokenizer) SetUnknownToken(tok string) {
tkz.UnknownToken = tok
}