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))