Python io 模块，IncrementalNewlineDecoder() 实例源码

def decode_source(source_bytes):
    """Decode bytes representing source code and return the string.
    Universal newline support is used in the decoding.
    """
    # source_bytes_readline = io.BytesIO(source_bytes).readline
    # encoding, _ = detect_encoding(source_bytes_readline)
    newline_decoder = io.IncrementalNewlineDecoder(None, True)
    return newline_decoder.decode(source_to_unicode(source_bytes))

def source_to_unicode(txt, errors='replace', skip_encoding_cookie=True):
    """Converts a bytes string with python source code to unicode.
    Unicode strings are passed through unchanged. Byte strings are checked
    for the python source file encoding cookie to determine encoding.
    txt can be either a bytes buffer or a string containing the source
    code.
    """
    if isinstance(txt, six.text_type):
        return txt
    if isinstance(txt, six.binary_type):
        buffer = io.BytesIO(txt)
    else:
        buffer = txt
    try:
        encoding, _ = detect_encoding(buffer.readline)
    except SyntaxError:
        encoding = "ascii"
    buffer.seek(0)

    newline_decoder = io.IncrementalNewlineDecoder(None, True)

    text = io.TextIOWrapper(buffer, encoding, errors=errors, line_buffering=True)
    text.mode = 'r'
    if skip_encoding_cookie:
        return u"".join(strip_encoding_cookie(text))
    else:
        return text.read()

def test_universal_newlines(self):
        # PEP 302 says universal newlines should be used.
        name = 'mod'
        mock = SourceOnlyLoaderMock('mod.file')
        source = "x = 42\r\ny = -13\r\n"
        mock.source = source.encode('utf-8')
        expect = io.IncrementalNewlineDecoder(None, True).decode(source)
        self.assertEqual(mock.get_source(name), expect)

def test_universal_newlines(self):
        # PEP 302 says universal newlines should be used.
        name = 'mod'
        mock = SourceOnlyLoaderMock('mod.file')
        source = "x = 42\r\ny = -13\r\n"
        mock.source = source.encode('utf-8')
        expect = io.IncrementalNewlineDecoder(None, True).decode(source)
        self.assertEqual(mock.get_source(name), expect)

def test_universal_newlines(self):
        # PEP 302 says universal newlines should be used.
        name = 'mod'
        mock = self.SourceOnlyLoaderMock('mod.file')
        source = "x = 42\r\ny = -13\r\n"
        mock.source = source.encode('utf-8')
        expect = io.IncrementalNewlineDecoder(None, True).decode(source)
        self.assertEqual(mock.get_source(name), expect)

def test_universal_newlines(self):
        # PEP 302 says universal newlines should be used.
        name = 'mod'
        mock = self.SourceOnlyLoaderMock('mod.file')
        source = "x = 42\r\ny = -13\r\n"
        mock.source = source.encode('utf-8')
        expect = io.IncrementalNewlineDecoder(None, True).decode(source)
        self.assertEqual(mock.get_source(name), expect)