| | """CSS Selectors based on XPath. |
| | |
| | This module supports selecting XML/HTML tags based on CSS selectors. |
| | See the `CSSSelector` class for details. |
| | |
| | This is a thin wrapper around cssselect 0.7 or later. |
| | """ |
| |
|
| |
|
| | from . import etree |
| | try: |
| | import cssselect as external_cssselect |
| | except ImportError: |
| | raise ImportError( |
| | 'cssselect does not seem to be installed. ' |
| | 'See https://pypi.org/project/cssselect/') |
| |
|
| |
|
| | SelectorSyntaxError = external_cssselect.SelectorSyntaxError |
| | ExpressionError = external_cssselect.ExpressionError |
| | SelectorError = external_cssselect.SelectorError |
| |
|
| |
|
| | __all__ = ['SelectorSyntaxError', 'ExpressionError', 'SelectorError', |
| | 'CSSSelector'] |
| |
|
| |
|
| | class LxmlTranslator(external_cssselect.GenericTranslator): |
| | """ |
| | A custom CSS selector to XPath translator with lxml-specific extensions. |
| | """ |
| | def xpath_contains_function(self, xpath, function): |
| | |
| | |
| | if function.argument_types() not in (['STRING'], ['IDENT']): |
| | raise ExpressionError( |
| | "Expected a single string or ident for :contains(), got %r" |
| | % function.arguments) |
| | value = function.arguments[0].value |
| | return xpath.add_condition( |
| | 'contains(__lxml_internal_css:lower-case(string(.)), %s)' |
| | % self.xpath_literal(value.lower())) |
| |
|
| |
|
| | class LxmlHTMLTranslator(LxmlTranslator, external_cssselect.HTMLTranslator): |
| | """ |
| | lxml extensions + HTML support. |
| | """ |
| |
|
| |
|
| | def _make_lower_case(context, s): |
| | return s.lower() |
| |
|
| | ns = etree.FunctionNamespace('http://codespeak.net/lxml/css/') |
| | ns.prefix = '__lxml_internal_css' |
| | ns['lower-case'] = _make_lower_case |
| |
|
| |
|
| | class CSSSelector(etree.XPath): |
| | """A CSS selector. |
| | |
| | Usage:: |
| | |
| | >>> from lxml import etree, cssselect |
| | >>> select = cssselect.CSSSelector("a tag > child") |
| | |
| | >>> root = etree.XML("<a><b><c/><tag><child>TEXT</child></tag></b></a>") |
| | >>> [ el.tag for el in select(root) ] |
| | ['child'] |
| | |
| | To use CSS namespaces, you need to pass a prefix-to-namespace |
| | mapping as ``namespaces`` keyword argument:: |
| | |
| | >>> rdfns = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#' |
| | >>> select_ns = cssselect.CSSSelector('root > rdf|Description', |
| | ... namespaces={'rdf': rdfns}) |
| | |
| | >>> rdf = etree.XML(( |
| | ... '<root xmlns:rdf="%s">' |
| | ... '<rdf:Description>blah</rdf:Description>' |
| | ... '</root>') % rdfns) |
| | >>> [(el.tag, el.text) for el in select_ns(rdf)] |
| | [('{http://www.w3.org/1999/02/22-rdf-syntax-ns#}Description', 'blah')] |
| | |
| | """ |
| | def __init__(self, css, namespaces=None, translator='xml'): |
| | if translator == 'xml': |
| | translator = LxmlTranslator() |
| | elif translator == 'html': |
| | translator = LxmlHTMLTranslator() |
| | elif translator == 'xhtml': |
| | translator = LxmlHTMLTranslator(xhtml=True) |
| | path = translator.css_to_xpath(css) |
| | super().__init__(path, namespaces=namespaces) |
| | self.css = css |
| |
|
| | def __repr__(self): |
| | return '<%s %x for %r>' % ( |
| | self.__class__.__name__, |
| | abs(id(self)), |
| | self.css) |
| |
|
