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#![cfg_attr(feature = "cargo-clippy", allow(clippy::new_without_default))]
use super::{Token, TokenFilter, TokenStream};
use rust_stemmers::{self, Algorithm};
#[derive(Debug, Serialize, Deserialize, Eq, PartialEq, Copy, Clone)]
#[allow(missing_docs)]
pub enum Language {
Arabic,
Danish,
Dutch,
English,
Finnish,
French,
German,
Greek,
Hungarian,
Italian,
Portuguese,
Romanian,
Russian,
Spanish,
Swedish,
Tamil,
Turkish,
}
impl Language {
fn algorithm(self) -> Algorithm {
use self::Language::*;
match self {
Arabic => Algorithm::Arabic,
Danish => Algorithm::Danish,
Dutch => Algorithm::Dutch,
English => Algorithm::English,
Finnish => Algorithm::Finnish,
French => Algorithm::French,
German => Algorithm::German,
Greek => Algorithm::Greek,
Hungarian => Algorithm::Hungarian,
Italian => Algorithm::Italian,
Portuguese => Algorithm::Portuguese,
Romanian => Algorithm::Romanian,
Russian => Algorithm::Russian,
Spanish => Algorithm::Spanish,
Swedish => Algorithm::Swedish,
Tamil => Algorithm::Tamil,
Turkish => Algorithm::Turkish,
}
}
}
#[derive(Clone)]
pub struct Stemmer {
stemmer_algorithm: Algorithm,
}
impl Stemmer {
pub fn new(language: Language) -> Stemmer {
Stemmer {
stemmer_algorithm: language.algorithm(),
}
}
}
impl Default for Stemmer {
fn default() -> Self {
Stemmer::new(Language::English)
}
}
impl<TailTokenStream> TokenFilter<TailTokenStream> for Stemmer
where
TailTokenStream: TokenStream,
{
type ResultTokenStream = StemmerTokenStream<TailTokenStream>;
fn transform(&self, token_stream: TailTokenStream) -> Self::ResultTokenStream {
let inner_stemmer = rust_stemmers::Stemmer::create(self.stemmer_algorithm);
StemmerTokenStream::wrap(inner_stemmer, token_stream)
}
}
pub struct StemmerTokenStream<TailTokenStream>
where
TailTokenStream: TokenStream,
{
tail: TailTokenStream,
stemmer: rust_stemmers::Stemmer,
}
impl<TailTokenStream> TokenStream for StemmerTokenStream<TailTokenStream>
where
TailTokenStream: TokenStream,
{
fn token(&self) -> &Token {
self.tail.token()
}
fn token_mut(&mut self) -> &mut Token {
self.tail.token_mut()
}
fn advance(&mut self) -> bool {
if !self.tail.advance() {
return false;
}
let stemmed_str: String = self.stemmer.stem(&self.token().text).into_owned();
self.token_mut().text.clear();
self.token_mut().text.push_str(&stemmed_str);
true
}
}
impl<TailTokenStream> StemmerTokenStream<TailTokenStream>
where
TailTokenStream: TokenStream,
{
fn wrap(
stemmer: rust_stemmers::Stemmer,
tail: TailTokenStream,
) -> StemmerTokenStream<TailTokenStream> {
StemmerTokenStream { tail, stemmer }
}
}