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- import codecs
- import locale
- import re
- import sys
- from typing import List, Tuple
- BOMS: List[Tuple[bytes, str]] = [
- (codecs.BOM_UTF8, "utf-8"),
- (codecs.BOM_UTF16, "utf-16"),
- (codecs.BOM_UTF16_BE, "utf-16-be"),
- (codecs.BOM_UTF16_LE, "utf-16-le"),
- (codecs.BOM_UTF32, "utf-32"),
- (codecs.BOM_UTF32_BE, "utf-32-be"),
- (codecs.BOM_UTF32_LE, "utf-32-le"),
- ]
- ENCODING_RE = re.compile(br"coding[:=]\s*([-\w.]+)")
- def auto_decode(data: bytes) -> str:
- """Check a bytes string for a BOM to correctly detect the encoding
- Fallback to locale.getpreferredencoding(False) like open() on Python3"""
- for bom, encoding in BOMS:
- if data.startswith(bom):
- return data[len(bom) :].decode(encoding)
- # Lets check the first two lines as in PEP263
- for line in data.split(b"\n")[:2]:
- if line[0:1] == b"#" and ENCODING_RE.search(line):
- result = ENCODING_RE.search(line)
- assert result is not None
- encoding = result.groups()[0].decode("ascii")
- return data.decode(encoding)
- return data.decode(
- locale.getpreferredencoding(False) or sys.getdefaultencoding(),
- )
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