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try:
from functools import lru_cache
except ImportError:
from functools32 import lru_cache
from cssselect import GenericTranslator as OriginalGenericTranslator
from cssselect import HTMLTranslator as OriginalHTMLTranslator
from cssselect.xpath import XPathExpr as OriginalXPathExpr
from cssselect.xpath import _unicode_safe_getattr, ExpressionError
from cssselect.parser import FunctionalPseudoElement
class XPathExpr(OriginalXPathExpr):
textnode = False
attribute = None
@classmethod
def from_xpath(cls, xpath, textnode=False, attribute=None):
x = cls(path=xpath.path, element=xpath.element, condition=xpath.condition)
x.textnode = textnode
x.attribute = attribute
return x
def __str__(self):
path = super(XPathExpr, self).__str__()
if self.textnode:
if path == '*':
path = 'text()'
elif path.endswith('::*/*'):
path = path[:-3] + 'text()'
else:
path += '/text()'
if self.attribute is not None:
if path.endswith('::*/*'):
path = path[:-2]
path += '/@%s' % self.attribute
return path
def join(self, combiner, other):
super(XPathExpr, self).join(combiner, other)
self.textnode = other.textnode
self.attribute = other.attribute
return self
class TranslatorMixin(object):
"""This mixin adds support to CSS pseudo elements via dynamic dispatch.
Currently supported pseudo-elements are ``::text`` and ``::attr(ATTR_NAME)``.
"""
def xpath_element(self, selector):
xpath = super(TranslatorMixin, self).xpath_element(selector)
return XPathExpr.from_xpath(xpath)
def xpath_pseudo_element(self, xpath, pseudo_element):
"""
Dispatch method that transforms XPath to support pseudo-element
"""
if isinstance(pseudo_element, FunctionalPseudoElement):
method = 'xpath_%s_functional_pseudo_element' % (
pseudo_element.name.replace('-', '_'))
method = _unicode_safe_getattr(self, method, None)
if not method:
raise ExpressionError(
"The functional pseudo-element ::%s() is unknown"
% pseudo_element.name)
xpath = method(xpath, pseudo_element)
else:
method = 'xpath_%s_simple_pseudo_element' % (
pseudo_element.replace('-', '_'))
method = _unicode_safe_getattr(self, method, None)
if not method:
raise ExpressionError(
"The pseudo-element ::%s is unknown"
% pseudo_element)
xpath = method(xpath)
return xpath
def xpath_attr_functional_pseudo_element(self, xpath, function):
"""Support selecting attribute values using ::attr() pseudo-element
"""
if function.argument_types() not in (['STRING'], ['IDENT']):
raise ExpressionError(
"Expected a single string or ident for ::attr(), got %r"
% function.arguments)
return XPathExpr.from_xpath(xpath,
attribute=function.arguments[0].value)
def xpath_text_simple_pseudo_element(self, xpath):
"""Support selecting text nodes using ::text pseudo-element"""
return XPathExpr.from_xpath(xpath, textnode=True)
class GenericTranslator(TranslatorMixin, OriginalGenericTranslator):
@lru_cache(maxsize=256)
def css_to_xpath(self, css, prefix='descendant-or-self::'):
return super(GenericTranslator, self).css_to_xpath(css, prefix)
class HTMLTranslator(TranslatorMixin, OriginalHTMLTranslator):
@lru_cache(maxsize=256)
def css_to_xpath(self, css, prefix='descendant-or-self::'):
return super(HTMLTranslator, self).css_to_xpath(css, prefix)
_translator = HTMLTranslator()
def css2xpath(query):
"Return translated XPath version of a given CSS query"
return _translator.css_to_xpath(query)
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