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+import numpy as np
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+import torch
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+import torch.nn.functional as F
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+from SwissArmyTransformer.generation.sampling_strategies.base_strategy import top_k_logits
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+from SwissArmyTransformer import get_tokenizer
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+from .utils import code_generation_end
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+
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+class CodeBaseStrategy:
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+ def __init__(self, language, batch_size, invalid_slices=[], temperature=1.0, top_k=200, eps=1e-4, top_p=0.0, end_tokens=None):
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+ self.language = language
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+ self.tokenizer = get_tokenizer()
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+ self.batch_size = batch_size
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+ self.invalid_slices = invalid_slices
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+ self.temperature = temperature
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+ self.topk = top_k
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+ self.top_p = top_p
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+ self.eps = eps
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+ if end_tokens is None:
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+ end_tokens = []
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+ self.end_tokens = end_tokens
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+ self._is_done = np.zeros(self.batch_size, dtype=np.bool)
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+
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+ @property
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+ def is_done(self) -> bool:
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+ return self._is_done.all()
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+
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+ def forward(self, logits, tokens, mems, context_length, temperature=None):
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+ logits = logits.view(-1, logits.size(-1))
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+ batch_size = tokens.shape[0]
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+ if temperature is None:
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+ temperature = self.temperature
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+ logits = logits / temperature
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+ for invalid_slice in self.invalid_slices:
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+ logits[..., invalid_slice] = -65504
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+
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+ logits = top_k_logits(logits, self.topk, self.top_p)
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+ probs = F.softmax(logits.float(), dim=-1) # float is essetial, due to a bug in Pytorch
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+ pred = torch.multinomial(probs, num_samples=1)
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+ for i in range(self.batch_size):
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+ if i >= batch_size:
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+ self._is_done[i] = True
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+ elif self._is_done[i]:
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+ pred[i] = -1
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+ elif pred[i].item() in self.end_tokens:
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+ self._is_done[i] = True
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+ tokens = torch.cat((tokens, pred.view(tokens.shape[:-1] + (1,))), dim=-1)
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+ for i in range(self.batch_size):
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+ if not self._is_done[i]:
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+ generation = self.tokenizer.tokenizer.decode(tokens[i].flatten()[context_length:])
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+ if code_generation_end(generation, self.language):
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+ self._is_done[i] = True
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+ return tokens, mems
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+
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+ def finalize(self, tokens, mems):
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+ self._is_done = np.zeros(self.batch_size, dtype=np.bool)
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+ return tokens, mems
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+
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+class CodeBeamSearchStrategy:
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+ def __init__(
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+ self,
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+ language,
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+ batch_size,
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+ num_beams,
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+ length_penalty=1.0,
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+ consider_end=False,
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+ end_tokens=[],
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+ invalid_slices=[],
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+ no_repeat_ngram_size=0,
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+ min_gen_length=0,
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+ deterministic=False,
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+ ):
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+ self.language = language
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+ self.batch_size = batch_size
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+ self.num_beams = num_beams
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+ self.length_penalty = length_penalty
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+ self.end_tokens = end_tokens
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+ self.ngram = no_repeat_ngram_size
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+ self.min_gen_length = min_gen_length
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+ self.invalid_slices = invalid_slices
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+ self.consider_end = consider_end
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+ self.deterministic = deterministic
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+ self._init_cache()
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+
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+ def _init_cache(self):
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+ self.end_beams = [[] for _ in range(self.batch_size)] # list of LongTensors
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+ self.end_beams_penalized_scores = [[] for _ in range(self.batch_size)] # list of LongTensors
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+ self.cached_beam_scores = 0 # [batch_size]
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+ self.cached_beam_ngram_bans = [[{} for _ in range(self.num_beams)] for _ in range(self.batch_size)]
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+ self.length_generated = 0
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+ self._is_done = np.zeros(self.batch_size, dtype=np.bool)
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+
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+ def _add_end_beams(self, score, beam, batch_idx):
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+ score = score / ((5.0 + len(beam)) / 6) ** self.length_penalty # Magic number for OpenNMT
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+ for i in range(len(self.end_beams[batch_idx]), -1, -1):
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+ if i == 0 or score < self.end_beams_penalized_scores[batch_idx][i - 1]:
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+ break
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+ self.end_beams[batch_idx].insert(i, beam)
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+ self.end_beams_penalized_scores[batch_idx].insert(i, score)
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+
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+ self.end_beams[batch_idx] = self.end_beams[batch_idx][: self.num_beams]
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+ self.end_beams_penalized_scores[batch_idx] = self.end_beams_penalized_scores[batch_idx][: self.num_beams]
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+
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+ @property
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+ def is_done(self) -> bool:
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+ return self._is_done.all()
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+
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+ def forward(self, logits, tokens, mems):
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+ batch_size, num_beams, vocab_size = logits.shape
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+ seq_len = tokens.shape[-1]
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+ logits = logits.float()
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+ for invalid_slice in self.invalid_slices:
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+ logits[..., invalid_slice] = -65504
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+ if self.min_gen_length > self.length_generated:
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+ for end_token in self.end_tokens:
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+ logits[..., end_token] = -65504
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+ if self.ngram > 0 and seq_len > self.ngram:
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+ for batch_idx in range(batch_size):
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+ for i in range(num_beams):
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+ ngram_prefix = tokens[batch_idx, i, -(self.ngram - 1) :].tolist() # TODO ngram=1
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+ for banned_index in self.cached_beam_ngram_bans[batch_idx][i].get(tuple(ngram_prefix), []):
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+ logits[batch_idx, i, banned_index] = -65504
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+
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+ next_token_scores = F.log_softmax(logits, dim=-1) # [batch_size, vocab_size]
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+ prev_scores = self.cached_beam_scores
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+ if isinstance(prev_scores, torch.Tensor):
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+ prev_scores = prev_scores[..., None].expand_as(next_token_scores)
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+ next_token_scores = next_token_scores + prev_scores
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+
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+ next_token_scores = next_token_scores.view(batch_size, num_beams * vocab_size)
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+
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+ probs = F.softmax(next_token_scores, dim=-1)
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+ if num_beams < self.num_beams: # First token
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+ probs = probs[..., :vocab_size]
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+ if self.deterministic:
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+ next_tokens = torch.topk(probs, k=(max(1, len(self.end_tokens)) + 1) * self.num_beams).indices # [2*nb]
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+ else:
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+ next_tokens = torch.multinomial(
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+ probs, num_samples=(max(1, len(self.end_tokens)) + 1) * self.num_beams
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+ ) # [2*nb]
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+ next_token_scores = next_token_scores[torch.arange(batch_size).unsqueeze(1), next_tokens]
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+ next_token_scores, _indices = torch.sort(next_token_scores, descending=True, dim=1)
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+ next_tokens = next_tokens[torch.arange(batch_size).unsqueeze(1), _indices]
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+
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+ next_indices = torch.div(next_tokens, vocab_size, rounding_mode="trunc")
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+ next_tokens = next_tokens % vocab_size
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+
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+ # select out end beams or continue beams
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+ beam_continue_batch, score_continue_batch, mems_continue_batch = [], [], []
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+ for batch_idx in range(batch_size):
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+ beam_continue = []
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+ scores_continue = []
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+ bans_continue = []
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+ mems_contiue = []
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+ for i in range(len(next_tokens[batch_idx])):
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+ beam = torch.cat((tokens[batch_idx, next_indices[batch_idx, i]], next_tokens[batch_idx, i : i + 1]))
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+ if not self._is_done[batch_idx] and int(next_tokens[batch_idx, i]) in self.end_tokens:
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+ self._add_end_beams(next_token_scores[batch_idx, i], beam, batch_idx)
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+ elif len(beam_continue) < self.num_beams:
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+ beam_continue.append(beam)
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+ mems_contiue.append(mems[:, batch_idx, next_indices[batch_idx, i]])
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+ # update caches
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+ scores_continue.append(next_token_scores[batch_idx, i])
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+ if self.ngram > 0:
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+ bans = self.cached_beam_ngram_bans[batch_idx][next_indices[batch_idx, i]].copy()
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+ # TODO ngram=1
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+ ngram_prefix = tuple(
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+ tokens[batch_idx, next_indices[batch_idx, i], -(self.ngram - 1) :].tolist()
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+ )
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+ bans[ngram_prefix] = bans.get(ngram_prefix, tuple()) + (next_tokens[batch_idx, i],)
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+ bans_continue.append(bans)
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+ else:
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+ break
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+ beam_continue_batch.append(torch.stack(beam_continue))
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+ mems_continue_batch.append(torch.stack(mems_contiue, dim=1))
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+ score_continue_batch.append(scores_continue)
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+ self.cached_beam_ngram_bans[batch_idx] = bans_continue
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+ tokens = torch.stack(beam_continue_batch)
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+ mems = torch.stack(mems_continue_batch, dim=1)
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+ self.cached_beam_scores = torch.tensor(score_continue_batch, device=logits.device)
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+ self.length_generated += 1
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+ for batch_idx in range(self.batch_size):
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+ if batch_idx >= batch_size:
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+ self._is_done[batch_idx] = True
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+ elif (
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+ len(self.end_beams[batch_idx]) == self.num_beams
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+ and self.end_beams_penalized_scores[batch_idx][-1]
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+ >= self.cached_beam_scores[batch_idx].max() / ((5.0 + (seq_len + 1)) / 6) ** self.length_penalty
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+ ): # We're done if none of current tokens will better than the worst in end_beams
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+ self._is_done[batch_idx] = True
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+
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+ return tokens, mems
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+
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+ def finalize(self, tokens, mems):
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+ if self.consider_end:
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+ batch_size, num_beams = tokens.shape[:2]
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+ for batch_idx in range(batch_size):
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+ if not self._is_done[batch_idx]:
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+ for i in range(num_beams):
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+ self._add_end_beams(self.cached_beam_scores[batch_idx, i], tokens[batch_idx, i], batch_idx)
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+ mems = None
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+ ret = self.end_beams[:batch_size]
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+ else:
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+ ret = tokens
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+ self._init_cache()
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+ return ret, mems
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