utf_8_sig.py 文件源码

def decode(self, input, errors='strict'):
        if len(input) < 3:
            if codecs.BOM_UTF8.startswith(input):
                # not enough data to decide if this is a BOM
                # => try again on the next call
                return ("", 0)
        elif input[:3] == codecs.BOM_UTF8:
            self.decode = codecs.utf_8_decode
            (output, consumed) = codecs.utf_8_decode(input[3:],errors)
            return (output, consumed+3)
        # (else) no BOM present
        self.decode = codecs.utf_8_decode
        return codecs.utf_8_decode(input, errors)

### encodings module API