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