File size: 14,604 Bytes
5d8f58f
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
# Copyright (c) Alibaba Cloud.
#
# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.

"""Generation support."""

from typing import Tuple, List, Union, Iterable

import numpy as np
import torch
import torch.nn.functional as F
from transformers import PreTrainedTokenizer
from transformers import logging
from transformers.generation import LogitsProcessor

logger = logging.get_logger(__name__)

# Types.
HistoryType = List[Tuple[str, str]]
TokensType = List[int]
BatchTokensType = List[List[int]]


def pad_batch(batch: BatchTokensType, pad_id: int, seq_length: int) -> BatchTokensType:
    for tokens in batch:
        context_length = len(tokens)
        if context_length < seq_length:
            tokens.extend([pad_id] * (seq_length - context_length))
    return batch


def get_ltor_masks_and_position_ids(
    data,
    eod_token,
    reset_position_ids,
    reset_attention_mask,
    eod_mask_loss,
):
    """Build masks and position id for left to right model."""

    # Extract batch size and sequence length.
    micro_batch_size, seq_length = data.size()

    # Attention mask (lower triangular).
    if reset_attention_mask:
        att_mask_batch = micro_batch_size
    else:
        att_mask_batch = 1
    attention_mask = torch.tril(
        torch.ones((att_mask_batch, seq_length, seq_length), device=data.device)
    ).view(att_mask_batch, 1, seq_length, seq_length)

    # Loss mask.
    loss_mask = torch.ones(data.size(), dtype=torch.float, device=data.device)
    if eod_mask_loss:
        loss_mask[data == eod_token] = 0.0

    # Position ids.
    position_ids = torch.arange(seq_length, dtype=torch.long, device=data.device)
    position_ids = position_ids.unsqueeze(0).expand_as(data)
    # We need to clone as the ids will be modifed based on batch index.
    if reset_position_ids:
        position_ids = position_ids.clone()

    if reset_position_ids or reset_attention_mask:
        # Loop through the batches:
        for b in range(micro_batch_size):

            # Find indecies where EOD token is.
            eod_index = position_ids[b, data[b] == eod_token]
            # Detach indecies from positions if going to modify positions.
            if reset_position_ids:
                eod_index = eod_index.clone()

            # Loop through EOD indecies:
            prev_index = 0
            for j in range(eod_index.size()[0]):
                i = eod_index[j]
                # Mask attention loss.
                if reset_attention_mask:
                    attention_mask[b, 0, (i + 1) :, : (i + 1)] = 0
                # Reset positions.
                if reset_position_ids:
                    position_ids[b, (i + 1) :] -= i + 1 - prev_index
                    prev_index = i + 1

    # Convert attention mask to binary:
    attention_mask = attention_mask < 0.5

    return attention_mask, loss_mask, position_ids


def get_batch(context_tokens: torch.LongTensor, eod_id: int):
    """Generate batch from context tokens."""
    # Move to GPU.
    tokens = context_tokens.contiguous().to(context_tokens.device)
    # Get the attention mask and postition ids.
    attention_mask, _, position_ids = get_ltor_masks_and_position_ids(
        tokens,
        eod_id,
        reset_position_ids=False,
        reset_attention_mask=False,
        eod_mask_loss=False,
    )
    return tokens, attention_mask, position_ids


def get_stop_words_ids(chat_format, tokenizer):
    if chat_format == "raw":
        stop_words_ids = [tokenizer.encode("Human:"), [tokenizer.eod_id]]
    elif chat_format == "chatml":
        stop_words_ids = [[tokenizer.im_end_id], [tokenizer.im_start_id]]
    else:
        raise NotImplementedError(f"Unknown chat format {chat_format!r}")
    return stop_words_ids


def make_context(
    tokenizer: PreTrainedTokenizer,
    query: str,
    history: List[Tuple[str, str]] = None,
    system: str = "",
    max_window_size: int = 6144,
    chat_format: str = "chatml",
):
    if history is None:
        history = []

    if chat_format == "chatml":
        im_start, im_end = "<|im_start|>", "<|im_end|>"
        im_start_tokens = [tokenizer.im_start_id]
        im_end_tokens = [tokenizer.im_end_id]
        nl_tokens = tokenizer.encode("\n")

        def _tokenize_str(role, content):
            return f"{role}\n{content}", tokenizer.encode(
                role, allowed_special=set()
            ) + nl_tokens + tokenizer.encode(content, allowed_special=set())

        system_text, system_tokens_part = _tokenize_str("system", system)
        system_tokens = im_start_tokens + system_tokens_part + im_end_tokens

        raw_text = ""
        context_tokens = []

        for turn_query, turn_response in reversed(history):
            query_text, query_tokens_part = _tokenize_str("user", turn_query)
            query_tokens = im_start_tokens + query_tokens_part + im_end_tokens
            response_text, response_tokens_part = _tokenize_str(
                "assistant", turn_response
            )
            response_tokens = im_start_tokens + response_tokens_part + im_end_tokens

            next_context_tokens = nl_tokens + query_tokens + nl_tokens + response_tokens
            prev_chat = (
                f"\n{im_start}{query_text}{im_end}\n{im_start}{response_text}{im_end}"
            )

            current_context_size = (
                len(system_tokens) + len(next_context_tokens) + len(context_tokens)
            )
            if current_context_size < max_window_size:
                context_tokens = next_context_tokens + context_tokens
                raw_text = prev_chat + raw_text
            else:
                break

        context_tokens = system_tokens + context_tokens
        raw_text = f"{im_start}{system_text}{im_end}" + raw_text
        context_tokens += (
            nl_tokens
            + im_start_tokens
            + _tokenize_str("user", query)[1]
            + im_end_tokens
            + nl_tokens
            + im_start_tokens
            + tokenizer.encode("assistant")
            + nl_tokens
        )
        raw_text += f"\n{im_start}user\n{query}{im_end}\n{im_start}assistant\n"

    elif chat_format == "raw":
        raw_text = query
        context_tokens = tokenizer.encode(raw_text)
    else:
        raise NotImplementedError(f"Unknown chat format {chat_format!r}")

    return raw_text, context_tokens


def _decode_default(
    tokens: List[int],
    *,
    stop_words: List[str],
    eod_words: List[str],
    tokenizer: PreTrainedTokenizer,
    raw_text_len: int,
    verbose: bool = False,
    return_end_reason: bool = False,
    errors: str='replace',
):
    trim_decode_tokens = tokenizer.decode(tokens, errors=errors)[raw_text_len:]
    if verbose:
        print("\nRaw Generate: ", trim_decode_tokens)

    end_reason = f"Gen length {len(tokens)}"
    for stop_word in stop_words:
        trim_decode_tokens = trim_decode_tokens.replace(stop_word, "").strip()
    for eod_word in eod_words:
        if eod_word in trim_decode_tokens:
            end_reason = f"Gen {eod_word!r}"
        trim_decode_tokens = trim_decode_tokens.split(eod_word)[0]
    trim_decode_tokens = trim_decode_tokens.strip()
    if verbose:
        print("\nEnd Reason:", end_reason)
        print("\nGenerate: ", trim_decode_tokens)

    if return_end_reason:
        return trim_decode_tokens, end_reason
    else:
        return trim_decode_tokens


def _decode_chatml(
    tokens: List[int],
    *,
    stop_words: List[str],
    eod_token_ids: List[int],
    tokenizer: PreTrainedTokenizer,
    raw_text_len: int,
    context_length: int,
    verbose: bool = False,
    return_end_reason: bool = False,
    errors: str='replace'
):
    end_reason = f"Gen length {len(tokens)}"
    eod_token_idx = context_length
    for eod_token_idx in range(context_length, len(tokens)):
        if tokens[eod_token_idx] in eod_token_ids:
            end_reason = f"Gen {tokenizer.decode([tokens[eod_token_idx]])!r}"
            break

    trim_decode_tokens = tokenizer.decode(tokens[:eod_token_idx], errors=errors)[raw_text_len:]
    if verbose:
        print("\nRaw Generate w/o EOD:", tokenizer.decode(tokens, errors=errors)[raw_text_len:])
        print("\nRaw Generate:", trim_decode_tokens)
        print("\nEnd Reason:", end_reason)
    for stop_word in stop_words:
        trim_decode_tokens = trim_decode_tokens.replace(stop_word, "").strip()
    trim_decode_tokens = trim_decode_tokens.strip()
    if verbose:
        print("\nGenerate:", trim_decode_tokens)

    if return_end_reason:
        return trim_decode_tokens, end_reason
    else:
        return trim_decode_tokens


def decode_tokens(
    tokens: Union[torch.LongTensor, TokensType],
    tokenizer: PreTrainedTokenizer,
    raw_text_len: int,
    context_length: int,
    chat_format: str,
    verbose: bool = False,
    return_end_reason: bool = False,
    errors: str="replace",
) -> str:
    if torch.is_tensor(tokens):
        tokens = tokens.cpu().numpy().tolist()

    if chat_format == "chatml":
        return _decode_chatml(
            tokens,
            stop_words=[],
            eod_token_ids=[tokenizer.im_start_id, tokenizer.im_end_id],
            tokenizer=tokenizer,
            raw_text_len=raw_text_len,
            context_length=context_length,
            verbose=verbose,
            return_end_reason=return_end_reason,
            errors=errors,
        )
    elif chat_format == "raw":
        return _decode_default(
            tokens,
            stop_words=["<|endoftext|>"],
            eod_words=["<|endoftext|>"],
            tokenizer=tokenizer,
            raw_text_len=raw_text_len,
            verbose=verbose,
            return_end_reason=return_end_reason,
            errors=errors,
        )
    else:
        raise NotImplementedError(f"Unknown chat format {chat_format!r}")


class StopWordsLogitsProcessor(LogitsProcessor):
    """
    :class:`transformers.LogitsProcessor` that enforces that when specified sequences appear, stop geration.

    Args:
        stop_words_ids (:obj:`List[List[int]]`):
            List of list of token ids of stop ids. In order to get the tokens of the words
            that should not appear in the generated text, use :obj:`tokenizer(bad_word,
            add_prefix_space=True).input_ids`.
        eos_token_id (:obj:`int`):
            The id of the `end-of-sequence` token.
    """

    def __init__(self, stop_words_ids: Iterable[Iterable[int]], eos_token_id: int):

        if not isinstance(stop_words_ids, List) or len(stop_words_ids) == 0:
            raise ValueError(
                f"`stop_words_ids` has to be a non-emtpy list, but is {stop_words_ids}."
            )
        if any(not isinstance(bad_word_ids, list) for bad_word_ids in stop_words_ids):
            raise ValueError(
                f"`stop_words_ids` has to be a list of lists, but is {stop_words_ids}."
            )
        if any(
            any(
                (not isinstance(token_id, (int, np.integer)) or token_id < 0)
                for token_id in stop_word_ids
            )
            for stop_word_ids in stop_words_ids
        ):
            raise ValueError(
                f"Each list in `stop_words_ids` has to be a list of positive integers, but is {stop_words_ids}."
            )

        self.stop_words_ids = list(
            filter(
                lambda bad_token_seq: bad_token_seq != [eos_token_id], stop_words_ids
            )
        )
        self.eos_token_id = eos_token_id
        for stop_token_seq in self.stop_words_ids:
            assert (
                len(stop_token_seq) > 0
            ), "Stop words token sequences {} cannot have an empty list".format(
                stop_words_ids
            )

    def __call__(
        self, input_ids: torch.LongTensor, scores: torch.FloatTensor
    ) -> torch.FloatTensor:
        stopped_samples = self._calc_stopped_samples(input_ids)
        for i, should_stop in enumerate(stopped_samples):
            if should_stop:
                scores[i, self.eos_token_id] = float(2**15)
        return scores

    def _tokens_match(self, prev_tokens: torch.LongTensor, tokens: List[int]) -> bool:
        if len(tokens) == 0:
            # if bad word tokens is just one token always ban it
            return True
        elif len(tokens) > len(prev_tokens):
            # if bad word tokens are longer then prev input_ids they can't be equal
            return False
        elif prev_tokens[-len(tokens) :].tolist() == tokens:
            # if tokens match
            return True
        else:
            return False

    def _calc_stopped_samples(self, prev_input_ids: Iterable[int]) -> Iterable[int]:
        stopped_samples = []
        for prev_input_ids_slice in prev_input_ids:
            match = False
            for stop_token_seq in self.stop_words_ids:
                if self._tokens_match(prev_input_ids_slice, stop_token_seq):
                    # if tokens do not match continue
                    match = True
                    break
            stopped_samples.append(match)

        return stopped_samples


def top_k_logits(logits, top_k=0, top_p=0.0, filter_value=-float("Inf")):
    """This function has been mostly taken from huggingface conversational
    ai code at
        https://medium.com/huggingface/how-to-build-a-state-of-the-art-
             conversational-ai-with-transfer-learning-2d818ac26313"""

    if top_k > 0:
        # Remove all tokens with a probability less than the
        # last token of the top-k
        indices_to_remove = logits < torch.topk(logits, top_k)[0][..., -1, None]
        logits[indices_to_remove] = filter_value

    if top_p > 0.0:
        # Cconvert to 1D
        sorted_logits, sorted_indices = torch.sort(logits, descending=True, dim=-1)
        cumulative_probs = torch.cumsum(F.softmax(sorted_logits, dim=-1), dim=-1)

        # Remove tokens with cumulative probability above the threshold
        sorted_indices_to_remove = cumulative_probs > top_p
        # Shift the indices to the right to keep also the first token
        # above the threshold
        sorted_indices_to_remove[..., 1:] = sorted_indices_to_remove[..., :-1].clone()
        sorted_indices_to_remove[..., 0] = 0
        for i in range(sorted_indices.size(0)):
            indices_to_remove = sorted_indices[i][sorted_indices_to_remove[i]]
            logits[i][indices_to_remove] = filter_value

    return logits


def switch(val1, val2, boolean):
    boolean = boolean.type_as(val1)
    return (1 - boolean) * val1 + boolean * val2