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Edit File: xpath.py
# -*- coding: utf-8 -*- """ cssselect.xpath =============== Translation of parsed CSS selectors to XPath expressions. :copyright: (c) 2007-2012 Ian Bicking and contributors. See AUTHORS for more details. :license: BSD, see LICENSE for more details. """ import re import typing import warnings from typing import Optional from cssselect.parser import ( parse, parse_series, PseudoElement, Selector, SelectorError, Tree, Element, Hash, Class, Function, Pseudo, Attrib, Negation, Relation, Matching, SpecificityAdjustment, CombinedSelector, ) @typing.no_type_check def _unicode_safe_getattr(obj, name, default=None): warnings.warn( "_unicode_safe_getattr is deprecated and will be removed in the" " next release, use getattr() instead", DeprecationWarning, stacklevel=2, ) return getattr(obj, name, default) class ExpressionError(SelectorError, RuntimeError): """Unknown or unsupported selector (eg. pseudo-class).""" #### XPath Helpers class XPathExpr: def __init__( self, path: str = "", element: str = "*", condition: str = "", star_prefix: bool = False ) -> None: self.path = path self.element = element self.condition = condition def __str__(self) -> str: path = str(self.path) + str(self.element) if self.condition: path += "[%s]" % self.condition return path def __repr__(self) -> str: return "%s[%s]" % (self.__class__.__name__, self) def add_condition(self, condition: str, conjuction: str = "and") -> "XPathExpr": if self.condition: self.condition = "(%s) %s (%s)" % (self.condition, conjuction, condition) else: self.condition = condition return self def add_name_test(self) -> None: if self.element == "*": # We weren't doing a test anyway return self.add_condition("name() = %s" % GenericTranslator.xpath_literal(self.element)) self.element = "*" def add_star_prefix(self) -> None: """ Append '*/' to the path to keep the context constrained to a single parent. """ self.path += "*/" def join( self, combiner: str, other: "XPathExpr", closing_combiner: Optional[str] = None, has_inner_condition: bool = False, ) -> "XPathExpr": path = str(self) + combiner # Any "star prefix" is redundant when joining. if other.path != "*/": path += other.path self.path = path if not has_inner_condition: self.element = other.element + closing_combiner if closing_combiner else other.element self.condition = other.condition else: self.element = other.element if other.condition: self.element += "[" + other.condition + "]" if closing_combiner: self.element += closing_combiner return self split_at_single_quotes = re.compile("('+)").split # The spec is actually more permissive than that, but don’t bother. # This is just for the fast path. # http://www.w3.org/TR/REC-xml/#NT-NameStartChar is_safe_name = re.compile("^[a-zA-Z_][a-zA-Z0-9_.-]*$").match # Test that the string is not empty and does not contain whitespace is_non_whitespace = re.compile(r"^[^ \t\r\n\f]+$").match #### Translation class GenericTranslator: """ Translator for "generic" XML documents. Everything is case-sensitive, no assumption is made on the meaning of element names and attribute names. """ #### #### HERE BE DRAGONS #### #### You are welcome to hook into this to change some behavior, #### but do so at your own risks. #### Until it has received a lot more work and review, #### I reserve the right to change this API in backward-incompatible ways #### with any minor version of cssselect. #### See https://github.com/scrapy/cssselect/pull/22 #### -- Simon Sapin. #### combinator_mapping = { " ": "descendant", ">": "child", "+": "direct_adjacent", "~": "indirect_adjacent", } attribute_operator_mapping = { "exists": "exists", "=": "equals", "~=": "includes", "|=": "dashmatch", "^=": "prefixmatch", "$=": "suffixmatch", "*=": "substringmatch", "!=": "different", # XXX Not in Level 3 but meh } #: The attribute used for ID selectors depends on the document language: #: http://www.w3.org/TR/selectors/#id-selectors id_attribute = "id" #: The attribute used for ``:lang()`` depends on the document language: #: http://www.w3.org/TR/selectors/#lang-pseudo lang_attribute = "xml:lang" #: The case sensitivity of document language element names, #: attribute names, and attribute values in selectors depends #: on the document language. #: http://www.w3.org/TR/selectors/#casesens #: #: When a document language defines one of these as case-insensitive, #: cssselect assumes that the document parser makes the parsed values #: lower-case. Making the selector lower-case too makes the comparaison #: case-insensitive. #: #: In HTML, element names and attributes names (but not attribute values) #: are case-insensitive. All of lxml.html, html5lib, BeautifulSoup4 #: and HTMLParser make them lower-case in their parse result, so #: the assumption holds. lower_case_element_names = False lower_case_attribute_names = False lower_case_attribute_values = False # class used to represent and xpath expression xpathexpr_cls = XPathExpr def css_to_xpath(self, css: str, prefix: str = "descendant-or-self::") -> str: """Translate a *group of selectors* to XPath. Pseudo-elements are not supported here since XPath only knows about "real" elements. :param css: A *group of selectors* as a string. :param prefix: This string is prepended to the XPath expression for each selector. The default makes selectors scoped to the context node’s subtree. :raises: :class:`~cssselect.SelectorSyntaxError` on invalid selectors, :class:`ExpressionError` on unknown/unsupported selectors, including pseudo-elements. :returns: The equivalent XPath 1.0 expression as a string. """ return " | ".join( self.selector_to_xpath(selector, prefix, translate_pseudo_elements=True) for selector in parse(css) ) def selector_to_xpath( self, selector: Selector, prefix: str = "descendant-or-self::", translate_pseudo_elements: bool = False, ) -> str: """Translate a parsed selector to XPath. :param selector: A parsed :class:`Selector` object. :param prefix: This string is prepended to the resulting XPath expression. The default makes selectors scoped to the context node’s subtree. :param translate_pseudo_elements: Unless this is set to ``True`` (as :meth:`css_to_xpath` does), the :attr:`~Selector.pseudo_element` attribute of the selector is ignored. It is the caller's responsibility to reject selectors with pseudo-elements, or to account for them somehow. :raises: :class:`ExpressionError` on unknown/unsupported selectors. :returns: The equivalent XPath 1.0 expression as a string. """ tree = getattr(selector, "parsed_tree", None) if not tree: raise TypeError("Expected a parsed selector, got %r" % (selector,)) xpath = self.xpath(tree) assert isinstance(xpath, self.xpathexpr_cls) # help debug a missing 'return' if translate_pseudo_elements and selector.pseudo_element: xpath = self.xpath_pseudo_element(xpath, selector.pseudo_element) return (prefix or "") + str(xpath) def xpath_pseudo_element(self, xpath: XPathExpr, pseudo_element: PseudoElement) -> XPathExpr: """Translate a pseudo-element. Defaults to not supporting pseudo-elements at all, but can be overridden by sub-classes. """ raise ExpressionError("Pseudo-elements are not supported.") @staticmethod def xpath_literal(s: str) -> str: s = str(s) if "'" not in s: s = "'%s'" % s elif '"' not in s: s = '"%s"' % s else: s = "concat(%s)" % ",".join( [ (("'" in part) and '"%s"' or "'%s'") % part for part in split_at_single_quotes(s) if part ] ) return s def xpath(self, parsed_selector: Tree) -> XPathExpr: """Translate any parsed selector object.""" type_name = type(parsed_selector).__name__ method = getattr(self, "xpath_%s" % type_name.lower(), None) if method is None: raise ExpressionError("%s is not supported." % type_name) return typing.cast(XPathExpr, method(parsed_selector)) # Dispatched by parsed object type def xpath_combinedselector(self, combined: CombinedSelector) -> XPathExpr: """Translate a combined selector.""" combinator = self.combinator_mapping[combined.combinator] method = getattr(self, "xpath_%s_combinator" % combinator) return typing.cast( XPathExpr, method(self.xpath(combined.selector), self.xpath(combined.subselector)) ) def xpath_negation(self, negation: Negation) -> XPathExpr: xpath = self.xpath(negation.selector) sub_xpath = self.xpath(negation.subselector) sub_xpath.add_name_test() if sub_xpath.condition: return xpath.add_condition("not(%s)" % sub_xpath.condition) else: return xpath.add_condition("0") def xpath_relation(self, relation: Relation) -> XPathExpr: xpath = self.xpath(relation.selector) combinator = relation.combinator subselector = relation.subselector right = self.xpath(subselector.parsed_tree) method = getattr( self, "xpath_relation_%s_combinator" % self.combinator_mapping[typing.cast(str, combinator.value)], ) return typing.cast(XPathExpr, method(xpath, right)) def xpath_matching(self, matching: Matching) -> XPathExpr: xpath = self.xpath(matching.selector) exprs = [self.xpath(selector) for selector in matching.selector_list] for e in exprs: e.add_name_test() if e.condition: xpath.add_condition(e.condition, "or") return xpath def xpath_specificityadjustment(self, matching: SpecificityAdjustment) -> XPathExpr: xpath = self.xpath(matching.selector) exprs = [self.xpath(selector) for selector in matching.selector_list] for e in exprs: e.add_name_test() if e.condition: xpath.add_condition(e.condition, "or") return xpath def xpath_function(self, function: Function) -> XPathExpr: """Translate a functional pseudo-class.""" method_name = "xpath_%s_function" % function.name.replace("-", "_") method = getattr(self, method_name, None) if not method: raise ExpressionError("The pseudo-class :%s() is unknown" % function.name) return typing.cast(XPathExpr, method(self.xpath(function.selector), function)) def xpath_pseudo(self, pseudo: Pseudo) -> XPathExpr: """Translate a pseudo-class.""" method_name = "xpath_%s_pseudo" % pseudo.ident.replace("-", "_") method = getattr(self, method_name, None) if not method: # TODO: better error message for pseudo-elements? raise ExpressionError("The pseudo-class :%s is unknown" % pseudo.ident) return typing.cast(XPathExpr, method(self.xpath(pseudo.selector))) def xpath_attrib(self, selector: Attrib) -> XPathExpr: """Translate an attribute selector.""" operator = self.attribute_operator_mapping[selector.operator] method = getattr(self, "xpath_attrib_%s" % operator) if self.lower_case_attribute_names: name = selector.attrib.lower() else: name = selector.attrib safe = is_safe_name(name) if selector.namespace: name = "%s:%s" % (selector.namespace, name) safe = safe and is_safe_name(selector.namespace) if safe: attrib = "@" + name else: attrib = "attribute::*[name() = %s]" % self.xpath_literal(name) if selector.value is None: value = None elif self.lower_case_attribute_values: value = typing.cast(str, selector.value.value).lower() else: value = selector.value.value return typing.cast(XPathExpr, method(self.xpath(selector.selector), attrib, value)) def xpath_class(self, class_selector: Class) -> XPathExpr: """Translate a class selector.""" # .foo is defined as [class~=foo] in the spec. xpath = self.xpath(class_selector.selector) return self.xpath_attrib_includes(xpath, "@class", class_selector.class_name) def xpath_hash(self, id_selector: Hash) -> XPathExpr: """Translate an ID selector.""" xpath = self.xpath(id_selector.selector) return self.xpath_attrib_equals(xpath, "@id", id_selector.id) def xpath_element(self, selector: Element) -> XPathExpr: """Translate a type or universal selector.""" element = selector.element if not element: element = "*" safe = True else: safe = bool(is_safe_name(element)) if self.lower_case_element_names: element = element.lower() if selector.namespace: # Namespace prefixes are case-sensitive. # http://www.w3.org/TR/css3-namespace/#prefixes element = "%s:%s" % (selector.namespace, element) safe = safe and bool(is_safe_name(selector.namespace)) xpath = self.xpathexpr_cls(element=element) if not safe: xpath.add_name_test() return xpath # CombinedSelector: dispatch by combinator def xpath_descendant_combinator(self, left: XPathExpr, right: XPathExpr) -> XPathExpr: """right is a child, grand-child or further descendant of left""" return left.join("/descendant-or-self::*/", right) def xpath_child_combinator(self, left: XPathExpr, right: XPathExpr) -> XPathExpr: """right is an immediate child of left""" return left.join("/", right) def xpath_direct_adjacent_combinator(self, left: XPathExpr, right: XPathExpr) -> XPathExpr: """right is a sibling immediately after left""" xpath = left.join("/following-sibling::", right) xpath.add_name_test() return xpath.add_condition("position() = 1") def xpath_indirect_adjacent_combinator(self, left: XPathExpr, right: XPathExpr) -> XPathExpr: """right is a sibling after left, immediately or not""" return left.join("/following-sibling::", right) def xpath_relation_descendant_combinator(self, left: XPathExpr, right: XPathExpr) -> XPathExpr: """right is a child, grand-child or further descendant of left; select left""" return left.join("[descendant::", right, closing_combiner="]", has_inner_condition=True) def xpath_relation_child_combinator(self, left: XPathExpr, right: XPathExpr) -> XPathExpr: """right is an immediate child of left; select left""" return left.join("[./", right, closing_combiner="]") def xpath_relation_direct_adjacent_combinator( self, left: XPathExpr, right: XPathExpr ) -> XPathExpr: """right is a sibling immediately after left; select left""" xpath = left.add_condition( "following-sibling::*[(name() = '{}') and (position() = 1)]".format(right.element) ) return xpath def xpath_relation_indirect_adjacent_combinator( self, left: XPathExpr, right: XPathExpr ) -> XPathExpr: """right is a sibling after left, immediately or not; select left""" return left.join("[following-sibling::", right, closing_combiner="]") # Function: dispatch by function/pseudo-class name def xpath_nth_child_function( self, xpath: XPathExpr, function: Function, last: bool = False, add_name_test: bool = True ) -> XPathExpr: try: a, b = parse_series(function.arguments) except ValueError: raise ExpressionError("Invalid series: '%r'" % function.arguments) # From https://www.w3.org/TR/css3-selectors/#structural-pseudos: # # :nth-child(an+b) # an+b-1 siblings before # # :nth-last-child(an+b) # an+b-1 siblings after # # :nth-of-type(an+b) # an+b-1 siblings with the same expanded element name before # # :nth-last-of-type(an+b) # an+b-1 siblings with the same expanded element name after # # So, # for :nth-child and :nth-of-type # # count(preceding-sibling::<nodetest>) = an+b-1 # # for :nth-last-child and :nth-last-of-type # # count(following-sibling::<nodetest>) = an+b-1 # # therefore, # count(...) - (b-1) ≡ 0 (mod a) # # if a == 0: # ~~~~~~~~~~ # count(...) = b-1 # # if a < 0: # ~~~~~~~~~ # count(...) - b +1 <= 0 # -> count(...) <= b-1 # # if a > 0: # ~~~~~~~~~ # count(...) - b +1 >= 0 # -> count(...) >= b-1 # work with b-1 instead b_min_1 = b - 1 # early-exit condition 1: # ~~~~~~~~~~~~~~~~~~~~~~~ # for a == 1, nth-*(an+b) means n+b-1 siblings before/after, # and since n ∈ {0, 1, 2, ...}, if b-1<=0, # there is always an "n" matching any number of siblings (maybe none) if a == 1 and b_min_1 <= 0: return xpath # early-exit condition 2: # ~~~~~~~~~~~~~~~~~~~~~~~ # an+b-1 siblings with a<0 and (b-1)<0 is not possible if a < 0 and b_min_1 < 0: return xpath.add_condition("0") # `add_name_test` boolean is inverted and somewhat counter-intuitive: # # nth_of_type() calls nth_child(add_name_test=False) if add_name_test: nodetest = "*" else: nodetest = "%s" % xpath.element # count siblings before or after the element if not last: siblings_count = "count(preceding-sibling::%s)" % nodetest else: siblings_count = "count(following-sibling::%s)" % nodetest # special case of fixed position: nth-*(0n+b) # if a == 0: # ~~~~~~~~~~ # count(***-sibling::***) = b-1 if a == 0: return xpath.add_condition("%s = %s" % (siblings_count, b_min_1)) expressions = [] if a > 0: # siblings count, an+b-1, is always >= 0, # so if a>0, and (b-1)<=0, an "n" exists to satisfy this, # therefore, the predicate is only interesting if (b-1)>0 if b_min_1 > 0: expressions.append("%s >= %s" % (siblings_count, b_min_1)) else: # if a<0, and (b-1)<0, no "n" satisfies this, # this is tested above as an early exist condition # otherwise, expressions.append("%s <= %s" % (siblings_count, b_min_1)) # operations modulo 1 or -1 are simpler, one only needs to verify: # # - either: # count(***-sibling::***) - (b-1) = n = 0, 1, 2, 3, etc., # i.e. count(***-sibling::***) >= (b-1) # # - or: # count(***-sibling::***) - (b-1) = -n = 0, -1, -2, -3, etc., # i.e. count(***-sibling::***) <= (b-1) # we we just did above. # if abs(a) != 1: # count(***-sibling::***) - (b-1) ≡ 0 (mod a) left = siblings_count # apply "modulo a" on 2nd term, -(b-1), # to simplify things like "(... +6) % -3", # and also make it positive with |a| b_neg = (-b_min_1) % abs(a) if b_neg != 0: b_neg_as_str = "+%s" % b_neg left = "(%s %s)" % (left, b_neg_as_str) expressions.append("%s mod %s = 0" % (left, a)) if len(expressions) > 1: template = "(%s)" else: template = "%s" xpath.add_condition(" and ".join(template % expression for expression in expressions)) return xpath def xpath_nth_last_child_function(self, xpath: XPathExpr, function: Function) -> XPathExpr: return self.xpath_nth_child_function(xpath, function, last=True) def xpath_nth_of_type_function(self, xpath: XPathExpr, function: Function) -> XPathExpr: if xpath.element == "*": raise ExpressionError("*: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: XPathExpr, function: Function) -> XPathExpr: 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: XPathExpr, function: Function) -> XPathExpr: # 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 = typing.cast(str, function.arguments[0].value) return xpath.add_condition("contains(., %s)" % self.xpath_literal(value)) def xpath_lang_function(self, xpath: XPathExpr, function: Function) -> XPathExpr: if function.argument_types() not in (["STRING"], ["IDENT"]): raise ExpressionError( "Expected a single string or ident for :lang(), got %r" % function.arguments ) value = typing.cast(str, 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: XPathExpr) -> XPathExpr: return xpath.add_condition("not(parent::*)") # CSS immediate children (CSS ":scope > div" to XPath "child::div" or "./div") # Works only at the start of a selector # Needed to get immediate children of a processed selector in Scrapy # for product in response.css('.product'): # description = product.css(':scope > div::text').get() def xpath_scope_pseudo(self, xpath: XPathExpr) -> XPathExpr: return xpath.add_condition("1") def xpath_first_child_pseudo(self, xpath: XPathExpr) -> XPathExpr: return xpath.add_condition("count(preceding-sibling::*) = 0") def xpath_last_child_pseudo(self, xpath: XPathExpr) -> XPathExpr: return xpath.add_condition("count(following-sibling::*) = 0") def xpath_first_of_type_pseudo(self, xpath: XPathExpr) -> XPathExpr: 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: XPathExpr) -> XPathExpr: 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: XPathExpr) -> XPathExpr: return xpath.add_condition("count(parent::*/child::*) = 1") def xpath_only_of_type_pseudo(self, xpath: XPathExpr) -> XPathExpr: 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: XPathExpr) -> XPathExpr: return xpath.add_condition("not(*) and not(string-length())") def pseudo_never_matches(self, xpath: XPathExpr) -> XPathExpr: """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: XPathExpr, name: str, value: Optional[str]) -> XPathExpr: assert not value xpath.add_condition(name) return xpath def xpath_attrib_equals(self, xpath: XPathExpr, name: str, value: Optional[str]) -> XPathExpr: assert value is not None xpath.add_condition("%s = %s" % (name, self.xpath_literal(value))) return xpath def xpath_attrib_different( self, xpath: XPathExpr, name: str, value: Optional[str] ) -> XPathExpr: assert value is not None # 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: XPathExpr, name: str, value: Optional[str] ) -> XPathExpr: if value and 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: XPathExpr, name: str, value: Optional[str] ) -> XPathExpr: assert value is not None # 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: XPathExpr, name: str, value: Optional[str] ) -> XPathExpr: 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: XPathExpr, name: str, value: Optional[str] ) -> XPathExpr: 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: XPathExpr, name: str, value: Optional[str] ) -> XPathExpr: 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: bool = False) -> None: 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: XPathExpr) -> XPathExpr: # type: ignore # 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: XPathExpr, function: Function) -> XPathExpr: 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 assert 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: XPathExpr) -> XPathExpr: # type: ignore 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: XPathExpr) -> XPathExpr: # type: ignore # 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: XPathExpr) -> XPathExpr: # type: ignore # 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."