add support for :has(<relative operator>)

[annbgn]

todo: uncomment tests and watch them fail, then fix

[codecov]

Codecov Report

Merging #115 (b4cbd4e) into master (9edc6c3) will increase coverage by 0.22%.
The diff coverage is 97.10%.

@@            Coverage Diff             @@
##           master     #115      +/-   ##
==========================================
+ Coverage   95.39%   95.61%   +0.22%     
==========================================
  Files           3        3              
  Lines         803      889      +86     
  Branches      139      152      +13     
==========================================
+ Hits          766      850      +84     
  Misses         20       20              
- Partials       17       19       +2     

Impacted Files	Coverage Δ
cssselect/xpath.py	94.65% <96.29%> (-0.12%)	⬇️
cssselect/parser.py	96.16% <97.61%> (+0.42%)	⬆️

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[wRAR]

Great!

[elacuesta]

Looks good! Do you think it would be possible to add some of the tests from #96?

Edit: In particular, I'm interested in this test, which doesn't work under the current version (b64eacf):

Python 3.8.2 (default, Apr 18 2020, 17:39:30) 
[GCC 7.5.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from cssselect import parse
>>> parse("div:has(div.foo)")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/eugenio/zyte/cssselect/cssselect/parser.py", line 475, in parse
    return list(parse_selector_group(stream))
  File "/home/eugenio/zyte/cssselect/cssselect/parser.py", line 488, in parse_selector_group
    yield Selector(*parse_selector(stream))
  File "/home/eugenio/zyte/cssselect/cssselect/parser.py", line 497, in parse_selector
    result, pseudo_element = parse_simple_selector(stream)
  File "/home/eugenio/zyte/cssselect/cssselect/parser.py", line 603, in parse_simple_selector
    arguments = parse_relative_selector(stream)
  File "/home/eugenio/zyte/cssselect/cssselect/parser.py", line 649, in parse_relative_selector
    raise SelectorSyntaxError(
cssselect.parser.SelectorSyntaxError: Expected an argument, got <DELIM '.' at 11>
>>>

[errorcode7]

cssselect 1.1.0 parsel 1.6.0 Scrapy 2.6.1

`In [58]: response.css("a:has(strong)")

TypeError Traceback (most recent call last)
in
----> 1 response.css("a:has(strong)")

/usr/local/lib/python3.7/dist-packages/scrapy/http/response/text.py in css(self, query)
129
130 def css(self, query):
--> 131 return self.selector.css(query)
132
133 def follow(self, url, callback=None, method='GET', headers=None, body=None,

/usr/local/lib/python3.7/dist-packages/parsel/selector.py in css(self, query)
280 .. _cssselect: https://pypi.python.org/pypi/cssselect/
281 """
--> 282 return self.xpath(self._css2xpath(query))
283
284 def _css2xpath(self, query):

/usr/local/lib/python3.7/dist-packages/parsel/selector.py in _css2xpath(self, query)
283
284 def _css2xpath(self, query):
--> 285 return self._csstranslator.css_to_xpath(query)
286
287 def re(self, regex, replace_entities=True):

/usr/local/lib/python3.7/dist-packages/parsel/csstranslator.py in css_to_xpath(self, css, prefix)
105 @lru_cache(maxsize=256)
106 def css_to_xpath(self, css, prefix='descendant-or-self::'):
--> 107 return super(HTMLTranslator, self).css_to_xpath(css, prefix)
108
109

/usr/local/lib/python3.7/dist-packages/cssselect/xpath.py in css_to_xpath(self, css, prefix)
198 return " | ".join(
199 self.selector_to_xpath(selector, prefix, translate_pseudo_elements=True)
--> 200 for selector in parse(css)
201 )
202

/usr/local/lib/python3.7/dist-packages/cssselect/xpath.py in (.0)
198 return " | ".join(
199 self.selector_to_xpath(selector, prefix, translate_pseudo_elements=True)
--> 200 for selector in parse(css)
201 )
202

/usr/local/lib/python3.7/dist-packages/cssselect/xpath.py in selector_to_xpath(self, selector, prefix, translate_pseudo_elements)
227 if not tree:
228 raise TypeError("Expected a parsed selector, got %r" % (selector,))
--> 229 xpath = self.xpath(tree)
230 assert isinstance(xpath, self.xpathexpr_cls) # help debug a missing 'return'
231 if translate_pseudo_elements and selector.pseudo_element:

/usr/local/lib/python3.7/dist-packages/cssselect/xpath.py in xpath(self, parsed_selector)
265 if method is None:
266 raise ExpressionError("%s is not supported." % type_name)
--> 267 return method(parsed_selector)
268
269 # Dispatched by parsed object type

/usr/local/lib/python3.7/dist-packages/cssselect/xpath.py in xpath_relation(self, relation)
293 "xpath_relation_%s_combinator" % self.combinator_mapping[combinator.value],
294 )
--> 295 return method(xpath, right)
296
297 def xpath_matching(self, matching):

/usr/local/lib/python3.7/dist-packages/cssselect/xpath.py in xpath_relation_descendant_combinator(self, left, right)
407 def xpath_relation_descendant_combinator(self, left, right):
408 """right is a child, grand-child or further descendant of left; select left"""
--> 409 return left.join("[descendant::", right, closing_combiner="]", has_inner_condition=True)
410
411 def xpath_relation_child_combinator(self, left, right):

TypeError: join() got an unexpected keyword argument 'closing_combiner'
hello ,cant use:hasin scrapy? how can i use pseudo-classhas` in scrapy css()?

[errorcode7]

i have installed cssselect with pip install cssselect-master.zip ,download from github.

[Gallaecio]

Please, open a separate issue with a minimal reproducible example instead of commenting on an already closed pull request. You can link this pull request from your new issue for reference.