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2026-07-13 13:25:10 +08:00

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Python

# Copyright FunASR (https://github.com/modelscope/FunASR). All Rights Reserved.
# MIT License (https://opensource.org/licenses/MIT)
"""Text-level hotword correction after ASR decoding.
This module is intentionally separate from model-level ``hotword`` / ``hotwords``
prompting. It runs after ASR (and punctuation / ITN when configured) and only
updates top-level ``text`` plus sentence-level ``text`` / ``sentence`` fields.
"""
from __future__ import annotations
import os
import re
from dataclasses import dataclass
from typing import Any, Dict, Iterable, List, Mapping, Optional, Sequence, Tuple, Union
HotwordInput = Union[str, Sequence[str], Mapping[str, str], None]
_EXPLICIT_SEPARATORS = ("=>", "->", "→")
_TOKEN_PATTERN = re.compile(r"[\u4e00-\u9fff]|[a-zA-Z]+|[0-9]+")
_LAZY_PINYIN = None
_PINYIN_STYLE = None
_RAPIDFUZZ_FUZZ = None
@dataclass(frozen=True)
class HotwordMatch:
"""A single postprocess hotword replacement."""
original: str
replacement: str
score: float
start: int
end: int
def as_dict(self) -> Dict[str, Any]:
return {
"original": self.original,
"replacement": self.replacement,
"score": self.score,
"start": self.start,
"end": self.end,
}
def _require_pypinyin():
global _LAZY_PINYIN, _PINYIN_STYLE
if _LAZY_PINYIN is None:
try:
from pypinyin import Style, lazy_pinyin
except ImportError as exc:
raise ImportError(
"postprocess hotword fuzzy matching requires pypinyin. "
"Install it with: pip install pypinyin"
) from exc
_LAZY_PINYIN = lazy_pinyin
_PINYIN_STYLE = Style
return _LAZY_PINYIN, _PINYIN_STYLE
def _require_rapidfuzz():
global _RAPIDFUZZ_FUZZ
if _RAPIDFUZZ_FUZZ is None:
try:
from rapidfuzz import fuzz
except ImportError as exc:
raise ImportError(
"postprocess hotword fuzzy matching requires rapidfuzz. "
"Install it with: pip install rapidfuzz"
) from exc
_RAPIDFUZZ_FUZZ = fuzz
return _RAPIDFUZZ_FUZZ
def _to_pinyin_key(text: str) -> str:
lazy_pinyin, style = _require_pypinyin()
return "".join(lazy_pinyin(text, style=style.NORMAL, errors="ignore")).lower()
def _parse_line(line: str) -> Tuple[Optional[str], Optional[str], bool]:
"""Parse one hotword file line.
Returns:
(wrong, right, is_explicit)
For fuzzy-only targets, wrong is None and right is the target word.
"""
stripped = line.strip()
if not stripped or stripped.startswith("#"):
return None, None, False
for sep in _EXPLICIT_SEPARATORS:
if sep in stripped:
wrong, right = stripped.split(sep, 1)
wrong = wrong.strip()
right = right.strip()
if wrong and right:
return wrong, right, True
return None, None, False
return None, stripped, False
def parse_hotword_file(path: str) -> Tuple[Dict[str, str], List[str]]:
if not os.path.isfile(path):
raise FileNotFoundError(f"postprocess_hotword_file not found: {path}")
explicit: Dict[str, str] = {}
fuzzy_targets: List[str] = []
with open(path, "r", encoding="utf-8") as f:
for line in f:
wrong, right, is_explicit = _parse_line(line)
if not right:
continue
if is_explicit and wrong is not None:
explicit[wrong] = right
else:
fuzzy_targets.append(right)
return explicit, fuzzy_targets
def parse_postprocess_hotwords(
postprocess_hotwords: HotwordInput,
) -> Tuple[Dict[str, str], List[str]]:
"""Parse in-memory hotword config into explicit and fuzzy buckets."""
explicit: Dict[str, str] = {}
fuzzy_targets: List[str] = []
if postprocess_hotwords is None:
return explicit, fuzzy_targets
if isinstance(postprocess_hotwords, str):
for line in postprocess_hotwords.splitlines():
wrong, right, is_explicit = _parse_line(line)
if not right:
continue
if is_explicit and wrong is not None:
explicit[wrong] = right
else:
fuzzy_targets.append(right)
return explicit, fuzzy_targets
if isinstance(postprocess_hotwords, Mapping):
for wrong, right in postprocess_hotwords.items():
wrong_s = str(wrong).strip()
right_s = str(right).strip()
if not right_s:
continue
if wrong_s and wrong_s != right_s:
explicit[wrong_s] = right_s
else:
fuzzy_targets.append(right_s)
return explicit, fuzzy_targets
if isinstance(postprocess_hotwords, Sequence) and not isinstance(postprocess_hotwords, (str, bytes)):
for item in postprocess_hotwords:
if item is None:
continue
item_s = str(item).strip()
if not item_s:
continue
wrong, right, is_explicit = _parse_line(item_s)
if is_explicit and wrong is not None:
explicit[wrong] = right
elif right:
fuzzy_targets.append(right)
return explicit, fuzzy_targets
raise TypeError(
"postprocess_hotwords must be None, str, list, or dict; "
f"got {type(postprocess_hotwords)!r}"
)
def build_postprocess_hotword_matcher(
postprocess_hotwords: HotwordInput = None,
postprocess_hotword_file: Optional[str] = None,
postprocess_hotword_threshold: float = 0.85,
enable_fuzzy: bool = True,
) -> Optional["PostprocessHotwordMatcher"]:
"""Compile a matcher once per ``generate()`` call."""
explicit: Dict[str, str] = {}
fuzzy_targets: List[str] = []
if postprocess_hotwords is not None:
e, f = parse_postprocess_hotwords(postprocess_hotwords)
explicit.update(e)
fuzzy_targets.extend(f)
if postprocess_hotword_file:
e, f = parse_hotword_file(postprocess_hotword_file)
explicit.update(e)
fuzzy_targets.extend(f)
if not explicit and not fuzzy_targets:
return None
return PostprocessHotwordMatcher(
explicit_map=explicit,
fuzzy_targets=fuzzy_targets,
threshold=postprocess_hotword_threshold,
enable_fuzzy=enable_fuzzy,
)
class PostprocessHotwordMatcher:
"""Compiled matcher reused across all results in one generate() call."""
def __init__(
self,
explicit_map: Optional[Dict[str, str]] = None,
fuzzy_targets: Optional[Iterable[str]] = None,
threshold: float = 0.85,
enable_fuzzy: bool = True,
):
self.explicit_map = dict(explicit_map or {})
self.threshold = float(threshold)
if not 0.0 <= self.threshold <= 1.0:
raise ValueError(
f"postprocess_hotword_threshold must be between 0.0 and 1.0, got {threshold}"
)
self.enable_fuzzy = bool(enable_fuzzy)
seen = set()
self.fuzzy_targets: List[str] = []
for target in fuzzy_targets or []:
target_s = str(target).strip()
if target_s and target_s not in seen:
seen.add(target_s)
self.fuzzy_targets.append(target_s)
self._length_buckets: Dict[int, List[Tuple[str, str]]] = {}
self._fuzz = None
if self.fuzzy_targets and self.enable_fuzzy:
self._fuzz = _require_rapidfuzz()
_require_pypinyin()
for target in self.fuzzy_targets:
bucket = self._length_buckets.setdefault(len(target), [])
bucket.append((target, _to_pinyin_key(target)))
def apply_text(self, text: str) -> Tuple[str, List[HotwordMatch]]:
if not text:
return text, []
matches: List[HotwordMatch] = []
updated = self._apply_explicit(text, matches)
if self.fuzzy_targets and self.enable_fuzzy:
updated, fuzzy_matches = self._apply_fuzzy(updated)
matches.extend(fuzzy_matches)
return updated, matches
def apply_result(self, result: Dict[str, Any], return_matches: bool = False) -> Dict[str, Any]:
text = result.get("text", "")
if not isinstance(text, str) or not text:
if return_matches:
result["postprocess_hotword_matches"] = []
return result
original_timestamp = result.get("timestamp")
new_text, matches = self.apply_text(text)
result["text"] = new_text
sentence_info = result.get("sentence_info")
if isinstance(sentence_info, list):
for sentence in sentence_info:
if not isinstance(sentence, dict):
continue
for field in ("text", "sentence"):
if field in sentence and isinstance(sentence[field], str):
corrected, _ = self.apply_text(sentence[field])
sentence[field] = corrected
if return_matches:
result["postprocess_hotword_matches"] = [m.as_dict() for m in matches]
# Timestamps intentionally remain aligned to the original recognition.
if original_timestamp is not None:
result["timestamp"] = original_timestamp
return result
def _apply_explicit(self, text: str, matches: List[HotwordMatch]) -> str:
if not self.explicit_map:
return text
updated = text
for wrong in sorted(self.explicit_map, key=len, reverse=True):
right = self.explicit_map[wrong]
start = 0
while True:
idx = updated.find(wrong, start)
if idx < 0:
break
end = idx + len(wrong)
matches.append(
HotwordMatch(
original=wrong,
replacement=right,
score=1.0,
start=idx,
end=end,
)
)
updated = updated[:idx] + right + updated[end:]
start = idx + len(right)
return updated
def _apply_fuzzy(self, text: str) -> Tuple[str, List[HotwordMatch]]:
assert self._fuzz is not None
candidates: List[HotwordMatch] = []
if not self._length_buckets:
return text, []
min_len = min(self._length_buckets)
max_len = max(self._length_buckets)
text_len = len(text)
for win_len in range(max(1, min_len - 1), max_len + 2):
bucket_keys = [
length
for length in (win_len - 1, win_len, win_len + 1)
if length in self._length_buckets
]
if not bucket_keys:
continue
for start in range(0, text_len - win_len + 1):
end = start + win_len
segment = text[start:end]
if not segment or not _TOKEN_PATTERN.search(segment):
continue
segment_py = _to_pinyin_key(segment)
for length in bucket_keys:
for target, target_py in self._length_buckets[length]:
if segment == target:
continue
score = self._fuzz.ratio(segment_py, target_py) / 100.0
if score >= self.threshold:
candidates.append(
HotwordMatch(
original=segment,
replacement=target,
score=round(score, 4),
start=start,
end=end,
)
)
if not candidates:
return text, []
selected = _select_non_overlapping(candidates)
updated = text
applied: List[HotwordMatch] = []
for match in sorted(selected, key=lambda m: m.start, reverse=True):
updated = updated[: match.start] + match.replacement + updated[match.end :]
applied.append(match)
applied.sort(key=lambda m: m.start)
return updated, applied
def _select_non_overlapping(candidates: List[HotwordMatch]) -> List[HotwordMatch]:
ranked = sorted(candidates, key=lambda m: (m.score, m.end - m.start), reverse=True)
selected: List[HotwordMatch] = []
occupied: List[Tuple[int, int]] = []
for candidate in ranked:
if any(not (candidate.end <= start or candidate.start >= end) for start, end in occupied):
continue
selected.append(candidate)
occupied.append((candidate.start, candidate.end))
return sorted(selected, key=lambda m: m.start)
def apply_postprocess_hotwords_to_results(
results: List[Dict[str, Any]],
cfg: Mapping[str, Any],
) -> List[Dict[str, Any]]:
"""Apply compiled matcher to each result dict if configured in cfg."""
matcher = build_postprocess_hotword_matcher(
postprocess_hotwords=cfg.get("postprocess_hotwords"),
postprocess_hotword_file=cfg.get("postprocess_hotword_file"),
postprocess_hotword_threshold=cfg.get("postprocess_hotword_threshold", 0.85),
enable_fuzzy=cfg.get("postprocess_hotword_fuzzy", True),
)
if matcher is None:
return results
return_matches = bool(
cfg.get("return_postprocess_hotword_matches", False)
)
for result in results:
if isinstance(result, dict):
matcher.apply_result(result, return_matches=return_matches)
return results