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- # The implementation is adopted from CLIP, made publicly available
- # under MIT License at https://github.com/openai/CLIP
- import gzip
- import html
- from functools import lru_cache
- import ftfy
- import regex as re
- import torch
- @lru_cache()
- def bytes_to_unicode():
- bs = list(range(ord('!'),
- ord('~') + 1)) + list(range(
- ord('¡'),
- ord('¬') + 1)) + list(range(ord('®'),
- ord('ÿ') + 1))
- cs = bs[:]
- n = 0
- for b in range(2**8):
- if b not in bs:
- bs.append(b)
- cs.append(2**8 + n)
- n += 1
- cs = [chr(n) for n in cs]
- return dict(zip(bs, cs))
- def get_pairs(word):
- pairs = set()
- prev_char = word[0]
- for char in word[1:]:
- pairs.add((prev_char, char))
- prev_char = char
- return pairs
- def basic_clean(text):
- text = ftfy.fix_text(text)
- text = html.unescape(html.unescape(text))
- return text.strip()
- def whitespace_clean(text):
- text = re.sub(r'\s+', ' ', text)
- text = text.strip()
- return text
- class SimpleTokenizer(object):
- def __init__(self, bpe_path):
- self.byte_encoder = bytes_to_unicode()
- self.byte_decoder = {v: k for k, v in self.byte_encoder.items()}
- merges = gzip.open(bpe_path).read().decode('utf-8').split('\n')
- merges = merges[1:49152 - 256 - 2 + 1]
- merges = [tuple(merge.split()) for merge in merges]
- vocab = list(bytes_to_unicode().values())
- vocab = vocab + [v + '</w>' for v in vocab]
- for merge in merges:
- vocab.append(''.join(merge))
- vocab.extend(['<|startoftext|>', '<|endoftext|>'])
- self.encoder = dict(zip(vocab, range(len(vocab))))
- self.decoder = {v: k for k, v in self.encoder.items()}
- self.bpe_ranks = dict(zip(merges, range(len(merges))))
- self.cache = {
- '<|startoftext|>': '<|startoftext|>',
- '<|endoftext|>': '<|endoftext|>'
- }
- self.pat = re.compile(
- r"""<\|startoftext\|>|<\|endoftext\|>|'s|'t|'re|'ve|'m|'ll|'d|[\p{L}]+|[\p{N}]|[^\s\p{L}\p{N}]+""",
- re.IGNORECASE)
- def bpe(self, token):
- if token in self.cache:
- return self.cache[token]
- word = tuple(token[:-1]) + (token[-1] + '</w>', )
- pairs = get_pairs(word)
- if not pairs:
- return token + '</w>'
- while True:
- bigram = min(
- pairs, key=lambda pair: self.bpe_ranks.get(pair, float('inf')))
- if bigram not in self.bpe_ranks:
- break
- first, second = bigram
- new_word = []
- i = 0
- while i < len(word):
- try:
- j = word.index(first, i)
- new_word.extend(word[i:j])
- i = j
- except ValueError:
- new_word.extend(word[i:])
- break
- if word[i] == first and i < len(word) - 1 and word[
- i + 1] == second:
- new_word.append(first + second)
- i += 2
- else:
- new_word.append(word[i])
- i += 1
- new_word = tuple(new_word)
- word = new_word
- if len(word) == 1:
- break
- else:
- pairs = get_pairs(word)
- word = ' '.join(word)
- self.cache[token] = word
- return word
- def encode(self, text):
- bpe_tokens = []
- text = whitespace_clean(basic_clean(text)).lower()
- for token in re.findall(self.pat, text):
- token = ''.join(self.byte_encoder[b]
- for b in token.encode('utf-8'))
- bpe_tokens.extend(self.encoder[bpe_token]
- for bpe_token in self.bpe(token).split(' '))
- return bpe_tokens
- def decode(self, tokens):
- text = ''.join([self.decoder[token] for token in tokens])
- text = bytearray([self.byte_decoder[c] for c in text]).decode(
- 'utf-8', errors='replace').replace('</w>', ' ')
- return text
- def tokenize(self, texts, context_length=77):
- if isinstance(texts, str):
- texts = [texts]
- sot_token = self.encoder['<|startoftext|>']
- eot_token = self.encoder['<|endoftext|>']
- all_tokens = [[sot_token] + self.encode(text) + [eot_token]
- for text in texts]
- result = torch.zeros(len(all_tokens), context_length, dtype=torch.int)
- for i, tokens in enumerate(all_tokens):
- if len(tokens) > context_length:
- tokens = tokens[:context_length]
- tokens[-1] = eot_token
- result[i, :len(tokens)] = torch.tensor(tokens)
- return result
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