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package tokenize
import "regexp"
// RegexpTokenizer splits a string into substrings using a regular expression.
type RegexpTokenizer struct {
regex *regexp.Regexp
gaps bool
discard bool
}
// NewRegexpTokenizer is a RegexpTokenizer constructor that takes three
// arguments: a pattern to base the tokenizer on, a boolean value indicating
// whether or not to look for separators between tokens, and boolean value
// indicating whether or not to discard empty tokens.
func NewRegexpTokenizer(pattern string, gaps, discard bool) *RegexpTokenizer {
rTok := RegexpTokenizer{
regex: regexp.MustCompile(pattern), gaps: gaps, discard: discard}
return &rTok
}
// Tokenize splits text into a slice of tokens according to its regexp pattern.
func (r RegexpTokenizer) Tokenize(text string) []string {
var tokens []string
if r.gaps {
temp := r.regex.Split(text, -1)
if r.discard {
for _, s := range temp {
if s != "" {
tokens = append(tokens, s)
}
}
} else {
tokens = temp
}
} else {
tokens = r.regex.FindAllString(text, -1)
}
return tokens
}
// NewBlanklineTokenizer is a RegexpTokenizer constructor.
//
// This tokenizer splits on any sequence of blank lines.
func NewBlanklineTokenizer() *RegexpTokenizer {
return &RegexpTokenizer{
regex: regexp.MustCompile(`\s*\n\s*\n\s*`), gaps: true, discard: true}
}
// NewWordPunctTokenizer is a RegexpTokenizer constructor.
//
// This tokenizer splits text into a sequence of alphabetic and non-alphabetic
// characters.
func NewWordPunctTokenizer() *RegexpTokenizer {
return &RegexpTokenizer{
regex: regexp.MustCompile(`\w+|[^\w\s]+`), gaps: false}
}
// NewWordBoundaryTokenizer is a RegexpTokenizer constructor.
//
// This tokenizer splits text into a sequence of word-like tokens.
func NewWordBoundaryTokenizer() *RegexpTokenizer {
return &RegexpTokenizer{
regex: regexp.MustCompile(`(?:[A-Z]\.){2,}|[\p{N}\p{L}']+`),
gaps: false}
}
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