Introduce code from Rust monorepo. This is a mess

tts/nemo/collections/common/tokenizers/char_tokenizer.py

@@ -0,0 +1,142 @@
+# Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
+#
+# 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.
+
+from typing import Optional
+
+from nemo.collections.common.tokenizers.tokenizer_spec import TokenizerSpec
+
+__all__ = ['CharTokenizer']
+
+
+class CharTokenizer(TokenizerSpec):
+    "Tokenizes each character"
+
+    def __init__(
+        self,
+        vocab_file: str,
+        mask_token: Optional[str] = None,
+        bos_token: Optional[str] = None,
+        eos_token: Optional[str] = None,
+        pad_token: Optional[str] = None,
+        sep_token: Optional[str] = None,
+        cls_token: Optional[str] = None,
+        unk_token: Optional[str] = None,
+    ):
+        """
+        Args:
+            vocab_file: path to file with vocabulary which consists
+                of characters separated by \n
+            mask_token: mask token 
+            bos_token: the beginning of sequence token
+            eos_token: the end of sequence token. Usually equal to sep_token
+            pad_token: token to use for padding
+            sep_token: token used for separating sequences
+            cls_token: class token. Usually equal to bos_token
+            unk_token: token to use for unknown tokens
+        """
+
+        vocab_list = open(vocab_file, "r").readlines()
+        self.vocab = {vocab_list[i].strip(): i for i in range(len(vocab_list))}
+
+        special_tokens_dict = {}
+        if unk_token:
+            special_tokens_dict["unk_token"] = unk_token
+        if sep_token:
+            special_tokens_dict["sep_token"] = sep_token
+        if mask_token:
+            special_tokens_dict["mask_token"] = mask_token
+        if bos_token:
+            special_tokens_dict["bos_token"] = bos_token
+        if eos_token:
+            special_tokens_dict["eos_token"] = eos_token
+        if pad_token:
+            special_tokens_dict["pad_token"] = pad_token
+        if cls_token:
+            special_tokens_dict["cls_token"] = cls_token
+
+        self.add_special_tokens(special_tokens_dict)
+        self.inv_vocab = {v: k for k, v in self.vocab.items()}
+        self.vocab_size = len(self.vocab)
+        self.special_tokens = self.tokens_to_ids(special_tokens_dict.values())
+
+    def add_special_tokens(self, special_tokens_dict: dict) -> int:
+        """
+        Adds a dictionary of special tokens (eos, pad, cls...).
+        If special tokens are NOT in the vocabulary, they are added
+        to it (indexed starting from the last index of the current vocabulary).
+        Args:
+            special_tokens_dict: dict of special tokens
+        """
+        for token in special_tokens_dict:
+            token_str = special_tokens_dict[token]
+            if token_str not in self.vocab:
+                self.vocab[token_str] = len(self.vocab)
+            setattr(self, token, token_str)
+
+    def text_to_tokens(self, text):
+        token_candidates = [char for char in text]
+        tokens = []
+        for token in token_candidates:
+            if token in self.vocab:
+                tokens.append(token)
+            else:
+                tokens.append(self.unk_token)
+        return tokens
+
+    def tokens_to_text(self, tokens):
+        return self.ids_to_text(self.tokens_to_ids(tokens))
+
+    def text_to_ids(self, text):
+        return [self.vocab[token] for token in self.text_to_tokens(text)]
+
+    def ids_to_text(self, ids):
+        ids_ = [id_ for id_ in ids if id_ not in self.special_tokens]
+        return "".join(self.ids_to_tokens(ids_))
+
+    def tokens_to_ids(self, tokens):
+        return [self.vocab[token] for token in tokens]
+
+    def token_to_id(self, token):
+        return self.vocab[token]
+
+    def ids_to_tokens(self, ids):
+        return [self.inv_vocab[id] for id in ids]
+
+    @property
+    def pad_id(self):
+        return self.vocab[self.pad_token]
+
+    @property
+    def bos_id(self):
+        return self.vocab[self.bos_token]
+
+    @property
+    def eos_id(self):
+        return self.vocab[self.eos_token]
+
+    @property
+    def unk_id(self):
+        return self.vocab[self.unk_token]
+
+    @property
+    def mask_id(self):
+        return self.vocab[self.mask_token]
+
+    @property
+    def sep_id(self):
+        return self.vocab[self.sep_token]
+
+    @property
+    def cls_id(self):
+        return self.vocab[self.cls_token]