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sglang/python/sglang/srt/constrained/reasoner_grammar_backend.py
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# Copyright 2023-2024 SGLang Team
# 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.
# ==============================================================================
"""The baseclass of a backend for reasoner grammar-guided constrained decoding."""
from typing import List, Optional, Tuple
import torch
from .base_grammar_backend import (
INVALID_GRAMMAR_OBJ,
BaseGrammarBackend,
BaseGrammarObject,
)
class ReasonerGrammarObject(BaseGrammarObject):
def __init__(self, grammar: BaseGrammarObject, think_end_id):
super().__init__()
self.grammar = grammar
self.think_end_id = think_end_id
# -1 means thinking has not ended yet
# 0 means just ended thinking in the last token
# + means number of tokens after thinking ended
self.tokens_after_think_end = -1
def transfer_state(self, token: int) -> int:
if self.tokens_after_think_end == -1 and token == self.think_end_id:
self.tokens_after_think_end = 0
elif self.tokens_after_think_end >= 0:
self.tokens_after_think_end += 1
def rollback_state(self):
if self.tokens_after_think_end == 0:
self.tokens_after_think_end = -1
elif self.tokens_after_think_end > 0:
self.tokens_after_think_end -= 1
def accept_token(self, token: int):
if self.tokens_after_think_end >= 0:
self.grammar.accept_token(token)
self.transfer_state(token)
def rollback(self, k):
steps_after_think = min(k, self.tokens_after_think_end)
if steps_after_think > 0:
self.grammar.rollback(steps_after_think)
for _ in range(k):
self.rollback_state()
def allocate_vocab_mask(
self, vocab_size: int, batch_size: int, device
) -> torch.Tensor:
return self.grammar.allocate_vocab_mask(vocab_size, batch_size, device)
def fill_vocab_mask(self, vocab_mask: torch.Tensor, idx: int) -> None:
if self.tokens_after_think_end >= 0:
self.grammar.fill_vocab_mask(vocab_mask, idx)
def move_vocab_mask(self, vocab_mask: torch.Tensor, device) -> torch.Tensor:
return self.grammar.move_vocab_mask(vocab_mask, device)
@property
def apply_vocab_mask(self):
return self.grammar.apply_vocab_mask
def copy(self) -> BaseGrammarObject:
return ReasonerGrammarObject(self.grammar.copy(), self.think_end_id)
@property
def finished(self):
return self.grammar.finished
@finished.setter
def finished(self, finished):
self.grammar.finished = finished
def try_jump_forward(self, tokenizer):
return self.grammar.try_jump_forward(tokenizer)
def jump_forward_str_state(self, helper):
return self.grammar.jump_forward_str_state(helper)
def jump_and_retokenize(
self, old_output_ids: List[int], new_output_ids: List[int], next_state: int
):
return self.grammar.jump_and_retokenize(
old_output_ids, new_output_ids, next_state
)
class ReasonerGrammarBackend(BaseGrammarBackend):
def __init__(self, grammar_backend: BaseGrammarBackend, think_end_id):
super().__init__()
self.grammar_backend = grammar_backend
self.think_end_id = think_end_id
def _init_value_dispatch(self, key: Tuple[str, str]) -> Optional[BaseGrammarObject]:
ret = self.grammar_backend._init_value_dispatch(key)
# avoid wrapping invalid grammar, so that the scheduler can detect it
if ret is None or ret is INVALID_GRAMMAR_OBJ:
return ret
return ReasonerGrammarObject(ret, self.think_end_id)