773 lines
27 KiB
Python
773 lines
27 KiB
Python
# -*- coding: utf-8 -*-
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"""
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cssselect.xpath
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===============
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Translation of parsed CSS selectors to XPath expressions.
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:copyright: (c) 2007-2012 Ian Bicking and contributors.
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See AUTHORS for more details.
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:license: BSD, see LICENSE for more details.
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"""
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import sys
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import re
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from cssselect.parser import parse, parse_series, SelectorError
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if sys.version_info[0] < 3:
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_basestring = basestring
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_unicode = unicode
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else:
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_basestring = str
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_unicode = str
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def _unicode_safe_getattr(obj, name, default=None):
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# getattr() with a non-ASCII name fails on Python 2.x
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name = name.encode('ascii', 'replace').decode('ascii')
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return getattr(obj, name, default)
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class ExpressionError(SelectorError, RuntimeError):
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"""Unknown or unsupported selector (eg. pseudo-class)."""
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#### XPath Helpers
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class XPathExpr(object):
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def __init__(self, path='', element='*', condition='', star_prefix=False):
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self.path = path
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self.element = element
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self.condition = condition
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def __str__(self):
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path = _unicode(self.path) + _unicode(self.element)
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if self.condition:
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path += '[%s]' % self.condition
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return path
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def __repr__(self):
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return '%s[%s]' % (self.__class__.__name__, self)
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def add_condition(self, condition):
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if self.condition:
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self.condition = '%s and (%s)' % (self.condition, condition)
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else:
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self.condition = condition
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return self
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def add_name_test(self):
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if self.element == '*':
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# We weren't doing a test anyway
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return
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self.add_condition(
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"name() = %s" % GenericTranslator.xpath_literal(self.element))
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self.element = '*'
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def add_star_prefix(self):
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"""
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Append '*/' to the path to keep the context constrained
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to a single parent.
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"""
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self.path += '*/'
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def join(self, combiner, other):
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path = _unicode(self) + combiner
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# Any "star prefix" is redundant when joining.
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if other.path != '*/':
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path += other.path
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self.path = path
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self.element = other.element
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self.condition = other.condition
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return self
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split_at_single_quotes = re.compile("('+)").split
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# The spec is actually more permissive than that, but don’t bother.
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# This is just for the fast path.
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# http://www.w3.org/TR/REC-xml/#NT-NameStartChar
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is_safe_name = re.compile('^[a-zA-Z_][a-zA-Z0-9_.-]*$').match
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# Test that the string is not empty and does not contain whitespace
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is_non_whitespace = re.compile(r'^[^ \t\r\n\f]+$').match
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#### Translation
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class GenericTranslator(object):
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"""
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Translator for "generic" XML documents.
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Everything is case-sensitive, no assumption is made on the meaning
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of element names and attribute names.
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"""
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####
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#### HERE BE DRAGONS
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####
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#### You are welcome to hook into this to change some behavior,
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#### but do so at your own risks.
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#### Until it has received a lot more work and review,
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#### I reserve the right to change this API in backward-incompatible ways
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#### with any minor version of cssselect.
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#### See https://github.com/scrapy/cssselect/pull/22
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#### -- Simon Sapin.
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####
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combinator_mapping = {
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' ': 'descendant',
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'>': 'child',
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'+': 'direct_adjacent',
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'~': 'indirect_adjacent',
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}
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attribute_operator_mapping = {
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'exists': 'exists',
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'=': 'equals',
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'~=': 'includes',
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'|=': 'dashmatch',
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'^=': 'prefixmatch',
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'$=': 'suffixmatch',
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'*=': 'substringmatch',
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'!=': 'different', # XXX Not in Level 3 but meh
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}
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#: The attribute used for ID selectors depends on the document language:
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#: http://www.w3.org/TR/selectors/#id-selectors
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id_attribute = 'id'
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#: The attribute used for ``:lang()`` depends on the document language:
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#: http://www.w3.org/TR/selectors/#lang-pseudo
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lang_attribute = 'xml:lang'
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#: The case sensitivity of document language element names,
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#: attribute names, and attribute values in selectors depends
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#: on the document language.
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#: http://www.w3.org/TR/selectors/#casesens
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#:
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#: When a document language defines one of these as case-insensitive,
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#: cssselect assumes that the document parser makes the parsed values
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#: lower-case. Making the selector lower-case too makes the comparaison
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#: case-insensitive.
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#:
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#: In HTML, element names and attributes names (but not attribute values)
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#: are case-insensitive. All of lxml.html, html5lib, BeautifulSoup4
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#: and HTMLParser make them lower-case in their parse result, so
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#: the assumption holds.
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lower_case_element_names = False
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lower_case_attribute_names = False
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lower_case_attribute_values = False
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# class used to represent and xpath expression
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xpathexpr_cls = XPathExpr
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def css_to_xpath(self, css, prefix='descendant-or-self::'):
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"""Translate a *group of selectors* to XPath.
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Pseudo-elements are not supported here since XPath only knows
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about "real" elements.
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:param css:
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A *group of selectors* as an Unicode string.
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:param prefix:
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This string is prepended to the XPath expression for each selector.
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The default makes selectors scoped to the context node’s subtree.
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:raises:
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:class:`SelectorSyntaxError` on invalid selectors,
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:class:`ExpressionError` on unknown/unsupported selectors,
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including pseudo-elements.
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:returns:
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The equivalent XPath 1.0 expression as an Unicode string.
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"""
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return ' | '.join(self.selector_to_xpath(selector, prefix,
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translate_pseudo_elements=True)
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for selector in parse(css))
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def selector_to_xpath(self, selector, prefix='descendant-or-self::',
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translate_pseudo_elements=False):
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"""Translate a parsed selector to XPath.
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:param selector:
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A parsed :class:`Selector` object.
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:param prefix:
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This string is prepended to the resulting XPath expression.
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The default makes selectors scoped to the context node’s subtree.
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:param translate_pseudo_elements:
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Unless this is set to ``True`` (as :meth:`css_to_xpath` does),
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the :attr:`~Selector.pseudo_element` attribute of the selector
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is ignored.
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It is the caller's responsibility to reject selectors
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with pseudo-elements, or to account for them somehow.
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:raises:
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:class:`ExpressionError` on unknown/unsupported selectors.
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:returns:
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The equivalent XPath 1.0 expression as an Unicode string.
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"""
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tree = getattr(selector, 'parsed_tree', None)
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if not tree:
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raise TypeError('Expected a parsed selector, got %r' % (selector,))
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xpath = self.xpath(tree)
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assert isinstance(xpath, self.xpathexpr_cls) # help debug a missing 'return'
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if translate_pseudo_elements and selector.pseudo_element:
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xpath = self.xpath_pseudo_element(xpath, selector.pseudo_element)
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return (prefix or '') + _unicode(xpath)
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def xpath_pseudo_element(self, xpath, pseudo_element):
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"""Translate a pseudo-element.
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Defaults to not supporting pseudo-elements at all,
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but can be overridden by sub-classes.
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"""
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raise ExpressionError('Pseudo-elements are not supported.')
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@staticmethod
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def xpath_literal(s):
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s = _unicode(s)
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if "'" not in s:
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s = "'%s'" % s
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elif '"' not in s:
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s = '"%s"' % s
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else:
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s = "concat(%s)" % ','.join([
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(("'" in part) and '"%s"' or "'%s'") % part
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for part in split_at_single_quotes(s) if part
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])
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return s
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def xpath(self, parsed_selector):
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"""Translate any parsed selector object."""
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type_name = type(parsed_selector).__name__
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method = getattr(self, 'xpath_%s' % type_name.lower(), None)
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if method is None:
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raise ExpressionError('%s is not supported.' % type_name)
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return method(parsed_selector)
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# Dispatched by parsed object type
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def xpath_combinedselector(self, combined):
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"""Translate a combined selector."""
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combinator = self.combinator_mapping[combined.combinator]
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method = getattr(self, 'xpath_%s_combinator' % combinator)
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return method(self.xpath(combined.selector),
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self.xpath(combined.subselector))
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def xpath_negation(self, negation):
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xpath = self.xpath(negation.selector)
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sub_xpath = self.xpath(negation.subselector)
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sub_xpath.add_name_test()
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if sub_xpath.condition:
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return xpath.add_condition('not(%s)' % sub_xpath.condition)
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else:
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return xpath.add_condition('0')
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def xpath_function(self, function):
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"""Translate a functional pseudo-class."""
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method = 'xpath_%s_function' % function.name.replace('-', '_')
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method = _unicode_safe_getattr(self, method, None)
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if not method:
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raise ExpressionError(
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"The pseudo-class :%s() is unknown" % function.name)
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return method(self.xpath(function.selector), function)
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def xpath_pseudo(self, pseudo):
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"""Translate a pseudo-class."""
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method = 'xpath_%s_pseudo' % pseudo.ident.replace('-', '_')
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method = _unicode_safe_getattr(self, method, None)
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if not method:
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# TODO: better error message for pseudo-elements?
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raise ExpressionError(
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"The pseudo-class :%s is unknown" % pseudo.ident)
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return method(self.xpath(pseudo.selector))
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def xpath_attrib(self, selector):
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"""Translate an attribute selector."""
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operator = self.attribute_operator_mapping[selector.operator]
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method = getattr(self, 'xpath_attrib_%s' % operator)
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if self.lower_case_attribute_names:
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name = selector.attrib.lower()
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else:
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name = selector.attrib
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safe = is_safe_name(name)
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if selector.namespace:
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name = '%s:%s' % (selector.namespace, name)
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safe = safe and is_safe_name(selector.namespace)
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if safe:
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attrib = '@' + name
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else:
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attrib = 'attribute::*[name() = %s]' % self.xpath_literal(name)
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if self.lower_case_attribute_values:
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value = selector.value.lower()
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else:
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value = selector.value
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return method(self.xpath(selector.selector), attrib, value)
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def xpath_class(self, class_selector):
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"""Translate a class selector."""
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# .foo is defined as [class~=foo] in the spec.
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xpath = self.xpath(class_selector.selector)
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return self.xpath_attrib_includes(
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xpath, '@class', class_selector.class_name)
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def xpath_hash(self, id_selector):
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"""Translate an ID selector."""
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xpath = self.xpath(id_selector.selector)
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return self.xpath_attrib_equals(xpath, '@id', id_selector.id)
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def xpath_element(self, selector):
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"""Translate a type or universal selector."""
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element = selector.element
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if not element:
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element = '*'
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safe = True
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else:
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safe = is_safe_name(element)
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if self.lower_case_element_names:
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element = element.lower()
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if selector.namespace:
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# Namespace prefixes are case-sensitive.
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# http://www.w3.org/TR/css3-namespace/#prefixes
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element = '%s:%s' % (selector.namespace, element)
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safe = safe and is_safe_name(selector.namespace)
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xpath = self.xpathexpr_cls(element=element)
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if not safe:
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xpath.add_name_test()
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return xpath
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# CombinedSelector: dispatch by combinator
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def xpath_descendant_combinator(self, left, right):
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"""right is a child, grand-child or further descendant of left"""
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return left.join('/descendant-or-self::*/', right)
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def xpath_child_combinator(self, left, right):
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"""right is an immediate child of left"""
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return left.join('/', right)
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def xpath_direct_adjacent_combinator(self, left, right):
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"""right is a sibling immediately after left"""
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xpath = left.join('/following-sibling::', right)
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xpath.add_name_test()
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return xpath.add_condition('position() = 1')
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def xpath_indirect_adjacent_combinator(self, left, right):
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"""right is a sibling after left, immediately or not"""
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return left.join('/following-sibling::', right)
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# Function: dispatch by function/pseudo-class name
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def xpath_nth_child_function(self, xpath, function, last=False,
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add_name_test=True):
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try:
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a, b = parse_series(function.arguments)
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except ValueError:
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raise ExpressionError("Invalid series: '%r'" % function.arguments)
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# From https://www.w3.org/TR/css3-selectors/#structural-pseudos:
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#
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# :nth-child(an+b)
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# an+b-1 siblings before
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#
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# :nth-last-child(an+b)
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# an+b-1 siblings after
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#
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# :nth-of-type(an+b)
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# an+b-1 siblings with the same expanded element name before
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#
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# :nth-last-of-type(an+b)
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# an+b-1 siblings with the same expanded element name after
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#
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# So,
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# for :nth-child and :nth-of-type
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#
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# count(preceding-sibling::<nodetest>) = an+b-1
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#
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# for :nth-last-child and :nth-last-of-type
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#
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# count(following-sibling::<nodetest>) = an+b-1
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#
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# therefore,
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# count(...) - (b-1) ≡ 0 (mod a)
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#
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# if a == 0:
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# ~~~~~~~~~~
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# count(...) = b-1
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#
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# if a < 0:
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# ~~~~~~~~~
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# count(...) - b +1 <= 0
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# -> count(...) <= b-1
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#
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# if a > 0:
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# ~~~~~~~~~
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# count(...) - b +1 >= 0
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# -> count(...) >= b-1
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# work with b-1 instead
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b_min_1 = b - 1
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# early-exit condition 1:
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# ~~~~~~~~~~~~~~~~~~~~~~~
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# for a == 1, nth-*(an+b) means n+b-1 siblings before/after,
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# and since n ∈ {0, 1, 2, ...}, if b-1<=0,
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# there is always an "n" matching any number of siblings (maybe none)
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if a == 1 and b_min_1 <=0:
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return xpath
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# early-exit condition 2:
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# ~~~~~~~~~~~~~~~~~~~~~~~
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# an+b-1 siblings with a<0 and (b-1)<0 is not possible
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if a < 0 and b_min_1 < 0:
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return xpath.add_condition('0')
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# `add_name_test` boolean is inverted and somewhat counter-intuitive:
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#
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# nth_of_type() calls nth_child(add_name_test=False)
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if add_name_test:
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nodetest = '*'
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else:
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nodetest = '%s' % xpath.element
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# count siblings before or after the element
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if not last:
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siblings_count = 'count(preceding-sibling::%s)' % nodetest
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else:
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siblings_count = 'count(following-sibling::%s)' % nodetest
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# special case of fixed position: nth-*(0n+b)
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# if a == 0:
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# ~~~~~~~~~~
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# count(***-sibling::***) = b-1
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if a == 0:
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return xpath.add_condition('%s = %s' % (siblings_count, b_min_1))
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expr = []
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if a > 0:
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# siblings count, an+b-1, is always >= 0,
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# so if a>0, and (b-1)<=0, an "n" exists to satisfy this,
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# therefore, the predicate is only interesting if (b-1)>0
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if b_min_1 > 0:
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expr.append('%s >= %s' % (siblings_count, b_min_1))
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else:
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# if a<0, and (b-1)<0, no "n" satisfies this,
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# this is tested above as an early exist condition
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# otherwise,
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expr.append('%s <= %s' % (siblings_count, b_min_1))
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# operations modulo 1 or -1 are simpler, one only needs to verify:
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#
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# - either:
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# count(***-sibling::***) - (b-1) = n = 0, 1, 2, 3, etc.,
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# i.e. count(***-sibling::***) >= (b-1)
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#
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# - or:
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# count(***-sibling::***) - (b-1) = -n = 0, -1, -2, -3, etc.,
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# i.e. count(***-sibling::***) <= (b-1)
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# we we just did above.
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#
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if abs(a) != 1:
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# count(***-sibling::***) - (b-1) ≡ 0 (mod a)
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left = siblings_count
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# apply "modulo a" on 2nd term, -(b-1),
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# to simplify things like "(... +6) % -3",
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# and also make it positive with |a|
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b_neg = (-b_min_1) % abs(a)
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if b_neg != 0:
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b_neg = '+%s' % b_neg
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left = '(%s %s)' % (left, b_neg)
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expr.append('%s mod %s = 0' % (left, a))
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xpath.add_condition(' and '.join(expr))
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return xpath
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def xpath_nth_last_child_function(self, xpath, function):
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return self.xpath_nth_child_function(xpath, function, last=True)
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def xpath_nth_of_type_function(self, xpath, function):
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if xpath.element == '*':
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raise ExpressionError(
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"*:nth-of-type() is not implemented")
|
||
return self.xpath_nth_child_function(xpath, function,
|
||
add_name_test=False)
|
||
|
||
def xpath_nth_last_of_type_function(self, xpath, function):
|
||
if xpath.element == '*':
|
||
raise ExpressionError(
|
||
"*:nth-of-type() is not implemented")
|
||
return self.xpath_nth_child_function(xpath, function, last=True,
|
||
add_name_test=False)
|
||
|
||
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(., %s)' % self.xpath_literal(value))
|
||
|
||
def xpath_lang_function(self, xpath, function):
|
||
if function.argument_types() not in (['STRING'], ['IDENT']):
|
||
raise ExpressionError(
|
||
"Expected a single string or ident for :lang(), got %r"
|
||
% function.arguments)
|
||
value = function.arguments[0].value
|
||
return xpath.add_condition(
|
||
"lang(%s)" % (self.xpath_literal(value)))
|
||
|
||
|
||
# Pseudo: dispatch by pseudo-class name
|
||
|
||
def xpath_root_pseudo(self, xpath):
|
||
return xpath.add_condition("not(parent::*)")
|
||
|
||
def xpath_first_child_pseudo(self, xpath):
|
||
return xpath.add_condition('count(preceding-sibling::*) = 0')
|
||
|
||
def xpath_last_child_pseudo(self, xpath):
|
||
return xpath.add_condition('count(following-sibling::*) = 0')
|
||
|
||
def xpath_first_of_type_pseudo(self, xpath):
|
||
if xpath.element == '*':
|
||
raise ExpressionError(
|
||
"*:first-of-type is not implemented")
|
||
return xpath.add_condition('count(preceding-sibling::%s) = 0' % xpath.element)
|
||
|
||
def xpath_last_of_type_pseudo(self, xpath):
|
||
if xpath.element == '*':
|
||
raise ExpressionError(
|
||
"*:last-of-type is not implemented")
|
||
return xpath.add_condition('count(following-sibling::%s) = 0' % xpath.element)
|
||
|
||
def xpath_only_child_pseudo(self, xpath):
|
||
return xpath.add_condition('count(parent::*/child::*) = 1')
|
||
|
||
def xpath_only_of_type_pseudo(self, xpath):
|
||
if xpath.element == '*':
|
||
raise ExpressionError(
|
||
"*:only-of-type is not implemented")
|
||
return xpath.add_condition('count(parent::*/child::%s) = 1' % xpath.element)
|
||
|
||
def xpath_empty_pseudo(self, xpath):
|
||
return xpath.add_condition("not(*) and not(string-length())")
|
||
|
||
def pseudo_never_matches(self, xpath):
|
||
"""Common implementation for pseudo-classes that never match."""
|
||
return xpath.add_condition("0")
|
||
|
||
xpath_link_pseudo = pseudo_never_matches
|
||
xpath_visited_pseudo = pseudo_never_matches
|
||
xpath_hover_pseudo = pseudo_never_matches
|
||
xpath_active_pseudo = pseudo_never_matches
|
||
xpath_focus_pseudo = pseudo_never_matches
|
||
xpath_target_pseudo = pseudo_never_matches
|
||
xpath_enabled_pseudo = pseudo_never_matches
|
||
xpath_disabled_pseudo = pseudo_never_matches
|
||
xpath_checked_pseudo = pseudo_never_matches
|
||
|
||
# Attrib: dispatch by attribute operator
|
||
|
||
def xpath_attrib_exists(self, xpath, name, value):
|
||
assert not value
|
||
xpath.add_condition(name)
|
||
return xpath
|
||
|
||
def xpath_attrib_equals(self, xpath, name, value):
|
||
xpath.add_condition('%s = %s' % (name, self.xpath_literal(value)))
|
||
return xpath
|
||
|
||
def xpath_attrib_different(self, xpath, name, value):
|
||
# FIXME: this seems like a weird hack...
|
||
if value:
|
||
xpath.add_condition('not(%s) or %s != %s'
|
||
% (name, name, self.xpath_literal(value)))
|
||
else:
|
||
xpath.add_condition('%s != %s'
|
||
% (name, self.xpath_literal(value)))
|
||
return xpath
|
||
|
||
def xpath_attrib_includes(self, xpath, name, value):
|
||
if is_non_whitespace(value):
|
||
xpath.add_condition(
|
||
"%s and contains(concat(' ', normalize-space(%s), ' '), %s)"
|
||
% (name, name, self.xpath_literal(' '+value+' ')))
|
||
else:
|
||
xpath.add_condition('0')
|
||
return xpath
|
||
|
||
def xpath_attrib_dashmatch(self, xpath, name, value):
|
||
# Weird, but true...
|
||
xpath.add_condition('%s and (%s = %s or starts-with(%s, %s))' % (
|
||
name,
|
||
name, self.xpath_literal(value),
|
||
name, self.xpath_literal(value + '-')))
|
||
return xpath
|
||
|
||
def xpath_attrib_prefixmatch(self, xpath, name, value):
|
||
if value:
|
||
xpath.add_condition('%s and starts-with(%s, %s)' % (
|
||
name, name, self.xpath_literal(value)))
|
||
else:
|
||
xpath.add_condition('0')
|
||
return xpath
|
||
|
||
def xpath_attrib_suffixmatch(self, xpath, name, value):
|
||
if value:
|
||
# Oddly there is a starts-with in XPath 1.0, but not ends-with
|
||
xpath.add_condition(
|
||
'%s and substring(%s, string-length(%s)-%s) = %s'
|
||
% (name, name, name, len(value)-1, self.xpath_literal(value)))
|
||
else:
|
||
xpath.add_condition('0')
|
||
return xpath
|
||
|
||
def xpath_attrib_substringmatch(self, xpath, name, value):
|
||
if value:
|
||
# Attribute selectors are case sensitive
|
||
xpath.add_condition('%s and contains(%s, %s)' % (
|
||
name, name, self.xpath_literal(value)))
|
||
else:
|
||
xpath.add_condition('0')
|
||
return xpath
|
||
|
||
|
||
class HTMLTranslator(GenericTranslator):
|
||
"""
|
||
Translator for (X)HTML documents.
|
||
|
||
Has a more useful implementation of some pseudo-classes based on
|
||
HTML-specific element names and attribute names, as described in
|
||
the `HTML5 specification`_. It assumes no-quirks mode.
|
||
The API is the same as :class:`GenericTranslator`.
|
||
|
||
.. _HTML5 specification: http://www.w3.org/TR/html5/links.html#selectors
|
||
|
||
:param xhtml:
|
||
If false (the default), element names and attribute names
|
||
are case-insensitive.
|
||
|
||
"""
|
||
|
||
lang_attribute = 'lang'
|
||
|
||
def __init__(self, xhtml=False):
|
||
self.xhtml = xhtml # Might be useful for sub-classes?
|
||
if not xhtml:
|
||
# See their definition in GenericTranslator.
|
||
self.lower_case_element_names = True
|
||
self.lower_case_attribute_names = True
|
||
|
||
def xpath_checked_pseudo(self, xpath):
|
||
# FIXME: is this really all the elements?
|
||
return xpath.add_condition(
|
||
"(@selected and name(.) = 'option') or "
|
||
"(@checked "
|
||
"and (name(.) = 'input' or name(.) = 'command')"
|
||
"and (@type = 'checkbox' or @type = 'radio'))")
|
||
|
||
def xpath_lang_function(self, xpath, function):
|
||
if function.argument_types() not in (['STRING'], ['IDENT']):
|
||
raise ExpressionError(
|
||
"Expected a single string or ident for :lang(), got %r"
|
||
% function.arguments)
|
||
value = function.arguments[0].value
|
||
return xpath.add_condition(
|
||
"ancestor-or-self::*[@lang][1][starts-with(concat("
|
||
# XPath 1.0 has no lower-case function...
|
||
"translate(@%s, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', "
|
||
"'abcdefghijklmnopqrstuvwxyz'), "
|
||
"'-'), %s)]"
|
||
% (self.lang_attribute, self.xpath_literal(value.lower() + '-')))
|
||
|
||
def xpath_link_pseudo(self, xpath):
|
||
return xpath.add_condition("@href and "
|
||
"(name(.) = 'a' or name(.) = 'link' or name(.) = 'area')")
|
||
|
||
# Links are never visited, the implementation for :visited is the same
|
||
# as in GenericTranslator
|
||
|
||
def xpath_disabled_pseudo(self, xpath):
|
||
# http://www.w3.org/TR/html5/section-index.html#attributes-1
|
||
return xpath.add_condition('''
|
||
(
|
||
@disabled and
|
||
(
|
||
(name(.) = 'input' and @type != 'hidden') or
|
||
name(.) = 'button' or
|
||
name(.) = 'select' or
|
||
name(.) = 'textarea' or
|
||
name(.) = 'command' or
|
||
name(.) = 'fieldset' or
|
||
name(.) = 'optgroup' or
|
||
name(.) = 'option'
|
||
)
|
||
) or (
|
||
(
|
||
(name(.) = 'input' and @type != 'hidden') or
|
||
name(.) = 'button' or
|
||
name(.) = 'select' or
|
||
name(.) = 'textarea'
|
||
)
|
||
and ancestor::fieldset[@disabled]
|
||
)
|
||
''')
|
||
# FIXME: in the second half, add "and is not a descendant of that
|
||
# fieldset element's first legend element child, if any."
|
||
|
||
def xpath_enabled_pseudo(self, xpath):
|
||
# http://www.w3.org/TR/html5/section-index.html#attributes-1
|
||
return xpath.add_condition('''
|
||
(
|
||
@href and (
|
||
name(.) = 'a' or
|
||
name(.) = 'link' or
|
||
name(.) = 'area'
|
||
)
|
||
) or (
|
||
(
|
||
name(.) = 'command' or
|
||
name(.) = 'fieldset' or
|
||
name(.) = 'optgroup'
|
||
)
|
||
and not(@disabled)
|
||
) or (
|
||
(
|
||
(name(.) = 'input' and @type != 'hidden') or
|
||
name(.) = 'button' or
|
||
name(.) = 'select' or
|
||
name(.) = 'textarea' or
|
||
name(.) = 'keygen'
|
||
)
|
||
and not (@disabled or ancestor::fieldset[@disabled])
|
||
) or (
|
||
name(.) = 'option' and not(
|
||
@disabled or ancestor::optgroup[@disabled]
|
||
)
|
||
)
|
||
''')
|
||
# FIXME: ... or "li elements that are children of menu elements,
|
||
# and that have a child element that defines a command, if the first
|
||
# such element's Disabled State facet is false (not disabled)".
|
||
# FIXME: after ancestor::fieldset[@disabled], add "and is not a
|
||
# descendant of that fieldset element's first legend element child,
|
||
# if any."
|