# The following comment should be removed at some point in the future.
# mypy: strict-optional=False
import codecs
import locale
import re
import sys
from pip._internal.utils.typing import MYPY_CHECK_RUNNING
if MYPY_CHECK_RUNNING:
from typing import List, Tuple, Text
BOMS = [
(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'),
] # type: List[Tuple[bytes, Text]]
ENCODING_RE = re.compile(br'coding[:=]\s*([-\w.]+)')
def auto_decode(data):
# type: (bytes) -> Text
"""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):
encoding = ENCODING_RE.search(line).groups()[0].decode('ascii')
return data.decode(encoding)
return data.decode(
locale.getpreferredencoding(False) or sys.getdefaultencoding(),
)
