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// Copyright 2020 The Trax Authors and The HuggingFace Inc. team.
// Copyright (c) 2018, NVIDIA CORPORATION. All rights reserved.
// Copyright 2020 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 crate::error::TokenizerError;
use crate::tokenizer::base_tokenizer::{Token, TokenRef};
use crate::tokenizer::tokenization_utils::{
bpe, clean_text, decompose_nfkc, fix_mask, is_whitespace, lowercase, split_on_bpe_pairs,
split_on_special_tokens, whitespace_tokenize, BpeCache,
};
use crate::tokenizer::{MultiThreadedTokenizer, Tokenizer};
use crate::vocab::{BpePairVocab, ReformerVocab, Vocab};
use crate::Mask;
use std::collections::HashMap;
use std::path::Path;
use std::sync::RwLock;
/// # Reformer tokenizer
pub struct ReformerTokenizer {
vocab: ReformerVocab,
bpe_ranks: BpePairVocab,
cache: BpeCache,
lower_case: bool,
}
impl ReformerTokenizer {
/// Create a new instance of a `ReformerTokenizer`
/// 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<ReformerTokenizer, TokenizerError> {
let vocab = ReformerVocab::from_file(&path)?;
let bpe_ranks = BpePairVocab::from_sentencepiece_file(path)?;
let cache = RwLock::new(HashMap::new());
Ok(ReformerTokenizer {
vocab,
bpe_ranks,
cache,
lower_case,
})
}
/// Create a new instance of a `ReformerTokenizer`
/// 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<ReformerTokenizer, TokenizerError> {
let vocab =
ReformerVocab::from_file_with_special_token_mapping(&path, special_token_mapping_path)?;
let bpe_ranks = BpePairVocab::from_sentencepiece_file(path)?;
let cache = RwLock::new(HashMap::new());
Ok(ReformerTokenizer {
vocab,
bpe_ranks,
cache,
lower_case,
})
}
}
impl Tokenizer<ReformerVocab> for ReformerTokenizer {
fn vocab(&self) -> &ReformerVocab {
&self.vocab
}
fn vocab_mut(&mut self) -> &mut ReformerVocab {
&mut self.vocab
}
fn tokenize_to_tokens(&self, text: TokenRef) -> Vec<Token> {
let mut tokens = split_on_special_tokens(text, &self.vocab)
.into_iter()
.flat_map(whitespace_tokenize)
.map(|token| token.to_owned())
.collect::<Vec<Token>>();
let mut sub_tokens = Vec::new();
for token in tokens.iter_mut() {
decompose_nfkc(token);
clean_text(token, true);
if !token.text.is_empty() {
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, token.reference_offsets[0]);
};
if token.mask != Mask::Special && token.mask != Mask::Unknown {
if self.lower_case {
lowercase(token);
}
sub_tokens.extend(split_on_bpe_pairs(
token.as_ref(),
bpe,
&self.bpe_ranks,
&self.cache,
false,
));
} else {
sub_tokens.push(token.to_owned());
}
}
// Consolidate consecutive unknown tokens
let mut prev_is_unk = false;
let mut indices_to_remove = vec![];
for (index, sub_token) in sub_tokens.iter_mut().enumerate() {
if self.vocab.values.get(&sub_token.text).is_none() {
sub_token.mask = Mask::Unknown;
}
if sub_token.mask == Mask::Unknown {
if prev_is_unk {
indices_to_remove.push(index);
}
prev_is_unk = true;
} else {
prev_is_unk = false;
}
}
for index_to_remove in indices_to_remove.into_iter().rev() {
sub_tokens.remove(index_to_remove);
}
}
fix_mask(&mut sub_tokens);
sub_tokens
}
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<ReformerVocab> for ReformerTokenizer {}