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from webencodings import UTF8, decode, lookup |
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from .parser import parse_stylesheet |
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def decode_stylesheet_bytes(css_bytes, protocol_encoding=None, |
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environment_encoding=None): |
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"""Determine the character encoding of a CSS stylesheet and decode it. |
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This is based on the presence of a :abbr:`BOM (Byte Order Mark)`, |
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a ``@charset`` rule, and encoding meta-information. |
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:type css_bytes: :obj:`bytes` |
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:param css_bytes: A CSS byte string. |
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:type protocol_encoding: :obj:`str` |
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:param protocol_encoding: |
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The encoding label, if any, defined by HTTP or equivalent protocol. |
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(e.g. via the ``charset`` parameter of the ``Content-Type`` header.) |
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:type environment_encoding: :class:`webencodings.Encoding` |
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:param environment_encoding: |
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The `environment encoding |
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<https://www.w3.org/TR/css-syntax/#environment-encoding>`_, if any. |
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:returns: |
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A 2-tuple of a decoded Unicode string and the |
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:class:`webencodings.Encoding` object that was used. |
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""" |
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if protocol_encoding: |
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fallback = lookup(protocol_encoding) |
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if fallback: |
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return decode(css_bytes, fallback) |
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if css_bytes.startswith(b'@charset "'): |
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end_quote = css_bytes.find(b'"', 10, 100) |
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if end_quote != -1 and css_bytes.startswith(b'";', end_quote): |
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fallback = lookup(css_bytes[10:end_quote].decode('latin1')) |
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if fallback: |
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if fallback.name in ('utf-16be', 'utf-16le'): |
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return decode(css_bytes, UTF8) |
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return decode(css_bytes, fallback) |
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if environment_encoding: |
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return decode(css_bytes, environment_encoding) |
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return decode(css_bytes, UTF8) |
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def parse_stylesheet_bytes(css_bytes, protocol_encoding=None, |
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environment_encoding=None, |
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skip_comments=False, skip_whitespace=False): |
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"""Parse :diagram:`stylesheet` from bytes, |
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determining the character encoding as web browsers do. |
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This is used when reading a file or fetching a URL. |
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The character encoding is determined from the initial bytes |
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(a :abbr:`BOM (Byte Order Mark)` or a ``@charset`` rule) |
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as well as the parameters. The ultimate fallback is UTF-8. |
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:type css_bytes: :obj:`bytes` |
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:param css_bytes: A CSS byte string. |
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:type protocol_encoding: :obj:`str` |
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:param protocol_encoding: |
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The encoding label, if any, defined by HTTP or equivalent protocol. |
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(e.g. via the ``charset`` parameter of the ``Content-Type`` header.) |
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:type environment_encoding: :class:`webencodings.Encoding` |
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:param environment_encoding: |
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The `environment encoding`_, if any. |
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:type skip_comments: :obj:`bool` |
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:param skip_comments: |
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Ignore CSS comments at the top-level of the stylesheet. |
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If the input is a string, ignore all comments. |
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:type skip_whitespace: :obj:`bool` |
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:param skip_whitespace: |
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Ignore whitespace at the top-level of the stylesheet. |
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Whitespace is still preserved |
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in the :attr:`~tinycss2.ast.QualifiedRule.prelude` |
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and the :attr:`~tinycss2.ast.QualifiedRule.content` of rules. |
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:returns: |
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A ``(rules, encoding)`` tuple. |
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* ``rules`` is a list of |
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:class:`~tinycss2.ast.QualifiedRule`, |
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:class:`~tinycss2.ast.AtRule`, |
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:class:`~tinycss2.ast.Comment` (if ``skip_comments`` is false), |
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:class:`~tinycss2.ast.WhitespaceToken` |
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(if ``skip_whitespace`` is false), |
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and :class:`~tinycss2.ast.ParseError` objects. |
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* ``encoding`` is the :class:`webencodings.Encoding` object |
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that was used. |
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If ``rules`` contains an ``@import`` rule, this is |
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the `environment encoding`_ for the imported stylesheet. |
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.. _environment encoding: |
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https://www.w3.org/TR/css-syntax/#environment-encoding |
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.. code-block:: python |
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response = urlopen('http://example.net/foo.css') |
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rules, encoding = parse_stylesheet_bytes( |
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css_bytes=response.read(), |
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# Python 3.x |
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protocol_encoding=response.info().get_content_type().get_param('charset'), |
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# Python 2.x |
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protocol_encoding=response.info().gettype().getparam('charset'), |
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) |
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for rule in rules: |
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... |
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""" |
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css_unicode, encoding = decode_stylesheet_bytes( |
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css_bytes, protocol_encoding, environment_encoding) |
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stylesheet = parse_stylesheet(css_unicode, skip_comments, skip_whitespace) |
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return stylesheet, encoding |
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