import codecs
import locale
import re
BOMS = [
(codecs.BOM_UTF8, 'utf8'),
(codecs.BOM_UTF16, 'utf16'),
(codecs.BOM_UTF16_BE, 'utf16-be'),
(codecs.BOM_UTF16_LE, 'utf16-le'),
(codecs.BOM_UTF32, 'utf32'),
(codecs.BOM_UTF32_BE, 'utf32-be'),
(codecs.BOM_UTF32_LE, 'utf32-le'),
]
ENCODING_RE = re.compile(b'coding[:=]\s*([-\w.]+)')
def auto_decode(data):
"""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))
