// Copyright 2016 Google Inc.
// Adapted from https://github.com/google/sentencepiece/blob/master/src/bpe_model.cc
// Copyright 2019-2021 Guillaume Becquin
// 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.
use std::path::Path;
use crate::error::TokenizerError;
use crate::tokenizer::tokenization_utils::{clean_text, decompose_nfkc, is_whitespace, lowercase};
use crate::tokenizer::{MultiThreadedTokenizer, Tokenizer};
use crate::vocab::{SentencePieceBpeModel, SentencePieceVocab, Vocab};
use crate::{Token, TokenRef};
/// # SentencePiece tokenizer
/// SentencePiece BPE tokenizer performing:
/// - text cleaning
/// - NFKC decomposition
/// - (optional) lower casing
/// - SentencePiece decomposition
pub struct SentencePieceBpeTokenizer {
model: SentencePieceBpeModel,
vocab: SentencePieceVocab,
lower_case: bool,
}
impl SentencePieceBpeTokenizer {
/// Create a new instance of a `SentencePieceBpeTokenizer`
/// Expects a SentencePiece protobuf file and special token mapping file as inputs.
///
/// # Parameters
/// - path (`&str`): path to the SentencePiece model file
/// - lower_case (`bool`): flag indicating if the text should be lower-cased as part of the tokenization
/// - strip_accents (`bool`): flag indicating if accents should be stripped from the text
/// - special_token_mapping_path (`&str`): path to a special token mapping file to overwrite default special tokens
///
/// # Example
///
/// ```no_run
/// use rust_tokenizers::tokenizer::{SentencePieceTokenizer, Tokenizer};
/// let lower_case = false;
/// let tokenizer = SentencePieceTokenizer::from_file_with_special_token_mapping(
/// "path/to/vocab/file",
/// lower_case,
/// "path/to/special/token/mapping/file",
/// )
/// .unwrap();
/// ```
pub fn from_file_with_special_token_mapping<P: AsRef<Path>, S: AsRef<Path>>(
path: P,
lower_case: bool,
special_token_mapping_path: S,
) -> Result<SentencePieceBpeTokenizer, TokenizerError> {
let model = SentencePieceBpeModel::from_file(&path)?;
let vocab = SentencePieceVocab::from_file_with_special_token_mapping(
path,
special_token_mapping_path,
)?;
Ok(SentencePieceBpeTokenizer {
model,
vocab,
lower_case,
})
}
/// Create a new instance of a `SentencePieceBpeTokenizer`
/// Expects a SentencePiece protobuf file as an input.
///
/// # Parameters
/// - path (`&str`): path to the SentencePiece model file
/// - lower_case (`bool`): flag indicating if the text should be lower-cased as part of the tokenization
/// - strip_accents (`bool`): flag indicating if accents should be stripped from the text
///
/// # Example
///
/// ```no_run
/// use rust_tokenizers::tokenizer::{SentencePieceTokenizer, Tokenizer};
/// let lower_case = false;
/// let tokenizer = SentencePieceTokenizer::from_file("path/to/vocab/file", lower_case).unwrap();
/// ```
pub fn from_file<P: AsRef<Path>>(
path: P,
lower_case: bool,
) -> Result<SentencePieceBpeTokenizer, TokenizerError> {
let model = SentencePieceBpeModel::from_file(&path)?;
let vocab = SentencePieceVocab::from_file(path)?;
Ok(SentencePieceBpeTokenizer {
model,
vocab,
lower_case,
})
}
/// Create a new instance of a `SentencePieceBpeTokenizer` from an existing vocabulary and model
///
/// # Parameters
/// - vocab (`SentencePieceVocab`): vocabulary
/// - model (`SentencePieceModel`): SentencePiece model
/// - lower_case (`bool`): flag indicating if the text should be lower-cased as part of the tokenization
/// - strip_accents (`bool`): flag indicating if accents should be stripped from the text
///
/// # Example
///
/// ```no_run
/// use rust_tokenizers::tokenizer::{SentencePieceBpeTokenizer, Tokenizer};
/// use rust_tokenizers::vocab::{SentencePieceBpeModel, SentencePieceVocab, Vocab};
/// let lower_case = false;
/// let vocab = SentencePieceVocab::from_file("path/to/vocab/file").unwrap();
/// let model = SentencePieceBpeModel::from_file("path/to/model/file").unwrap();
///
/// let tokenizer =
/// SentencePieceBpeTokenizer::from_existing_vocab_and_model(vocab, model, lower_case);
/// ```
pub fn from_existing_vocab_and_model(
vocab: SentencePieceVocab,
model: SentencePieceBpeModel,
lower_case: bool,
) -> SentencePieceBpeTokenizer {
SentencePieceBpeTokenizer {
model,
vocab,
lower_case,
}
}
}
impl Tokenizer<SentencePieceVocab> for SentencePieceBpeTokenizer {
fn vocab(&self) -> &SentencePieceVocab {
&self.vocab
}
fn tokenize_to_tokens(&self, text: TokenRef) -> Vec<Token> {
let mut token = text.to_owned();
clean_text(&mut token, true);
decompose_nfkc(&mut token);
if self.lower_case {
lowercase(&mut token);
}
token.text = token.text.replace(|c: char| is_whitespace(&c), "\u{2581}");
if !token.text.starts_with('\u{2581}') {
token.text.insert(0, '\u{2581}');
token.reference_offsets.insert(0, 0);
};
self.model.tokenize_to_tokens(token.as_ref())
}
fn convert_tokens_to_string(&self, tokens: Vec<String>) -> String {
tokens
.into_iter()
.map(|v| v.replace('\u{2581}', " "))
.collect::<Vec<String>>()
.join("")
}
}
impl MultiThreadedTokenizer<SentencePieceVocab> for SentencePieceBpeTokenizer {}