add support for :has(<relative operator>)

Author: annbgn

cssselect/parser.py

@@ -250,6 +250,30 @@ def specificity(self):
         return a1 + a2, b1 + b2, c1 + c2
 
 
+class Relation(object):
+    """
+    Represents selector:has(subselector)
+    """
+    def __init__(self, selector, subselector):
+        self.selector = selector
+        self.subselector = subselector
+
+    def __repr__(self):
+        return '%s[%r:has(%r)]' % (
+            self.__class__.__name__, self.selector, self.subselector)
+
+    def canonical(self):
+        subsel = self.subselector.canonical()
+        if len(subsel) > 1:
+            subsel = subsel.lstrip('*')
+        return '%s:has(%s)' % (self.selector.canonical(), subsel)
+
+    def specificity(self):
+        a1, b1, c1 = self.selector.specificity()
+        a2, b2, c2 = self.subselector.specificity()
+        return a1 + a2, b1 + b2, c1 + c2
+
+
 class Attrib(object):
     """
     Represents selector[namespace|attrib operator value]
@@ -538,6 +562,9 @@ def parse_simple_selector(stream, inside_negation=False):
                 if next != ('DELIM', ')'):
                     raise SelectorSyntaxError("Expected ')', got %s" % (next,))
                 result = Negation(result, argument)
+            elif ident.lower() == 'has':
+                arguments = parse_relative_selector(stream)
+                result = Relation(result, arguments)
             else:
                 result = Function(result, ident, parse_arguments(stream))
         else:
@@ -564,6 +591,24 @@ def parse_arguments(stream):
                 "Expected an argument, got %s" % (next,))
 
 
+def parse_relative_selector(stream):
+    arguments = []
+    stream.skip_whitespace()
+    next = stream.next()
+    if next in [('DELIM', '+'), ('DELIM', '-'), ('DELIM', '>'), ('DELIM', '~')]:
+        arguments.append(next)
+    while 1:
+        stream.skip_whitespace()
+        next = stream.next()
+        if next.type in ('IDENT', 'STRING', 'NUMBER'):
+            arguments.append(Element(element=next.value))
+        elif next == ('DELIM', ')'):
+            return arguments
+        else:
+            raise SelectorSyntaxError(
+                "Expected an argument, got %s" % (next,))
+
+
 def parse_attrib(selector, stream):
     stream.skip_whitespace()
     attrib = stream.next_ident_or_star()

cssselect/xpath.py

@@ -272,6 +272,12 @@ def xpath_negation(self, negation):
         else:
             return xpath.add_condition('0')
 
+    def xpath_relation(self, relation):
+        xpath = self.xpath(relation.selector)
+        combinator, subselector, *_ = relation.subselector
+        method = getattr(self, 'xpath_%s_combinator' % self.combinator_mapping[combinator.value])
+        return method(xpath, self.xpath(subselector))
+
     def xpath_function(self, function):
         """Translate a functional pseudo-class."""
         method = 'xpath_%s_function' % function.name.replace('-', '_')

tests/test_cssselect.py

@@ -266,6 +266,13 @@ def specificity(css):
         assert specificity(':not(:empty)') == (0, 1, 0)
         assert specificity(':not(#foo)') == (1, 0, 0)
 
+        # assert specificity(':has(*)') == (0, 0, 0)
+        # assert specificity(':has(foo)') == (0, 0, 1)
+        # assert specificity(':has(.foo)') == (0, 1, 0)
+        # assert specificity(':has([foo])') == (0, 1, 0)
+        # assert specificity(':has(:empty)') == (0, 1, 0)
+        # assert specificity(':has(#foo)') == (1, 0, 0)
+
         assert specificity('foo:empty') == (0, 1, 1)
         assert specificity('foo:before') == (0, 0, 2)
         assert specificity('foo::before') == (0, 0, 2)
@@ -300,6 +307,12 @@ def css2css(css, res=None):
         css2css(':not(*[foo])', ':not([foo])')
         css2css(':not(:empty)')
         css2css(':not(#foo)')
+        # css2css(':has(*)')
+        # css2css(':has(foo)')
+        # css2css(':has(*.foo)', ':has(.foo)')
+        # css2css(':has(*[foo])', ':has([foo])')
+        # css2css(':has(:empty)')
+        # css2css(':has(#foo)')
         css2css('foo:empty')
         css2css('foo::before')
         css2css('foo:empty::before')
@@ -492,6 +505,7 @@ def xpath(css):
             "e[not(count(preceding-sibling::*) mod 2 = 0)]")
         assert xpath('e:nOT(*)') == (
             "e[0]")  # never matches
+        assert xpath('e:has(> f)') == 'e/f'
         assert xpath('e f') == (
             "e/descendant-or-self::*/f")
         assert xpath('e > f') == (
@@ -863,6 +877,9 @@ def pcss(main, *selectors, **kwargs):
         assert pcss('ol :Not(li[class])') == [
             'first-li', 'second-li', 'li-div',
             'fifth-li', 'sixth-li', 'seventh-li']
+        # assert pcss('link:has(*)') == []
+        # assert pcss('link:has([href])') == ['link-href']
+        # assert pcss('ol:has(div)') == ['first-ol']
         assert pcss('ol.a.b.c > li.c:nth-child(3)') == ['third-li']
 
         # Invalid characters in XPath element names, should not crash