52 lines
1.6 KiB
Python
52 lines
1.6 KiB
Python
"""SRT 条目解析与序列化：正文可多行或为空，保留原始毫秒时间戳。"""
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from __future__ import annotations
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import re
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from dataclasses import dataclass
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_TIMESTAMP = re.compile(r"^(\d{2,}:\d{2}:\d{2},\d{3})\s*-->\s*(\d{2,}:\d{2}:\d{2},\d{3})$")
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@dataclass(frozen=True)
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class Cue:
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"""一个字幕条目；序号在输出时重排，时间戳与多行正文独立保存。"""
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start: str
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end: str
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text: str
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def parse_srt(text: str) -> list[Cue]:
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"""解析合法 SRT，兼容 BOM、CRLF、多余空行、空 cue 和末尾无空行。
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非空的坏条目明确报错，避免静默漏字幕；空文件返回空列表。
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"""
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lines = text.lstrip("\ufeff").splitlines()
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entries = []
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index = 0
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while index < len(lines):
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if not lines[index].strip():
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index += 1
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continue
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if not lines[index].strip().isdigit() or index + 1 >= len(lines):
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raise ValueError(f"invalid SRT index at line {index + 1}")
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match = _TIMESTAMP.fullmatch(lines[index + 1].strip())
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if match is None:
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raise ValueError(f"invalid SRT timestamp at line {index + 2}")
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index += 2
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body = []
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while index < len(lines) and lines[index].strip():
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body.append(lines[index])
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index += 1
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entries.append(Cue(match[1], match[2], "\n".join(body)))
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return entries
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def serialize_srt(entries: list[Cue]) -> str:
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"""按条目输出连续序号，空正文仍保留该条目的时间轴。"""
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return "\n".join(
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f"{i}\n{cue.start} --> {cue.end}\n{cue.text}\n"
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for i, cue in enumerate(entries, 1)
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)
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