You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
103 lines
3.3 KiB
103 lines
3.3 KiB
"""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 __future__ import absolute_import
|
|
|
|
from . import etree
|
|
try:
|
|
import cssselect as external_cssselect
|
|
except ImportError:
|
|
raise ImportError(
|
|
'cssselect does not seem to be installed. '
|
|
'See http://packages.python.org/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):
|
|
# Defined there, removed in later drafts:
|
|
# http://www.w3.org/TR/2001/CR-css3-selectors-20011113/#content-selectors
|
|
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)
|
|
etree.XPath.__init__(self, path, namespaces=namespaces)
|
|
self.css = css
|
|
|
|
def __repr__(self):
|
|
return '<%s %s for %r>' % (
|
|
self.__class__.__name__,
|
|
hex(abs(id(self)))[2:],
|
|
self.css)
|