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CSS 3 Modules
=============
.. _selectors3:
Selectors 3
-----------
.. currentmodule:: tinycss.css21
On :attr:`RuleSet.selector`, the :meth:`~.token_data.TokenList.as_css` method
can be used to serialize a selector back to an Unicode string.
>>> import tinycss
>>> stylesheet = tinycss.make_parser().parse_stylesheet(
... 'div.error, #root > section:first-letter { color: red }')
>>> selector_string = stylesheet.rules[0].selector.as_css()
>>> selector_string
'div.error, #root > section:first-letter'
This string can be parsed by cssselect_. The parsed objects have information
about pseudo-elements and selector specificity.
.. _cssselect: http://packages.python.org/cssselect/
>>> import cssselect
>>> selectors = cssselect.parse(selector_string)
>>> [s.specificity() for s in selectors]
[(0, 1, 1), (1, 0, 2)]
>>> [s.pseudo_element for s in selectors]
[None, 'first-letter']
These objects can in turn be translated to XPath expressions. Note that
the translation ignores pseudo-elements, you have to account for them
somehow or reject selectors with pseudo-elements.
>>> xpath = cssselect.HTMLTranslator().selector_to_xpath(selectors[1])
>>> xpath
"descendant-or-self::*[@id = 'root']/section"
Finally, the XPath expressions can be used with lxml_ to find the matching
elements.
>>> from lxml import etree
>>> compiled_selector = etree.XPath(xpath)
>>> document = etree.fromstring('''<section id="root">
... <section id="head">Title</section>
... <section id="content">
... Lorem <section id="sub-section">ipsum</section>
... </section>
... </section>''')
>>> [el.get('id') for el in compiled_selector(document)]
['head', 'content']
.. _lxml: http://lxml.de/xpathxslt.html#xpath
Find more details in the `cssselect documentation`_.
.. _cssselect documentation: http://packages.python.org/cssselect/
.. module:: tinycss.color3
Color 3
-------
This module implements parsing for the *<color>* values, as defined in
`CSS 3 Color <http://www.w3.org/TR/css3-color/>`_.
The (deprecated) CSS2 system colors are not supported, but you can
easily test for them if you want as they are simple ``IDENT`` tokens.
For example::
if token.type == 'IDENT' and token.value == 'ButtonText':
return ...
All other values types *are* supported:
* Basic, extended (X11) and transparent color keywords;
* 3-digit and 6-digit hexadecimal notations;
* ``rgb()``, ``rgba()``, ``hsl()`` and ``hsla()`` functional notations.
* ``currentColor``
This module does not integrate with a parser class. Instead, it provides
a function that can parse tokens as found in :attr:`.css21.Declaration.value`,
for example.
.. autofunction:: parse_color
.. autofunction:: parse_color_string
.. autoclass:: RGBA
.. module:: tinycss.page3
Paged Media 3
-------------
.. autoclass:: CSSPage3Parser
.. autoclass:: MarginRule
.. module:: tinycss.fonts3
Fonts 3
-------
.. autoclass:: CSSFonts3Parser
.. autoclass:: FontFaceRule
.. autoclass:: FontFeatureValuesRule
.. autoclass:: FontFeatureRule
Other CSS modules
-----------------
To add support for new CSS syntax, see :ref:`extending`.
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