revert earlier change and instead restrict RATIO regular expression t…

…o prevent use in calc

src/css_parser/css/value.py

@@ -755,9 +755,7 @@ def _setCssText(self, cssText):
         )
 
         def _operant(): return Choice(_DimensionProd(self),
-                                      _CSSVariableProd(self),
-                                      PreDef.ratio(),
-                                     )
+                                      _CSSVariableProd(self))
 
         prods = Sequence(Prod(name='CALC',
                               match=lambda t, v: t == types.FUNCTION and

src/css_parser/cssproductions.py

@@ -1,5 +1,4 @@
-"""productions for css_parser based on a mix of CSS 2.1 and CSS 3 Syntax
-productions
+"""productions for css_parser based on a mix of CSS 2.1 and CSS 3 Syntax productions
 
 - http://www.w3.org/TR/css3-syntax
 - http://www.w3.org/TR/css3-syntax/#grammar0
@@ -76,7 +75,7 @@
 
     ('S', r'{s}+'),  # 1st in list of general productions
     ('URI', r'{U}{R}{L}\({w}({string}|{url}*){w}\)'),
-    ('RATIO', r'{w}[0-9]+{w}\/{w}[0-9]+'),
+    ('RATIO', r'(?<!\(){w}[0-9]+{w}\/{w}[0-9]+(?=\))'),
     ('UNICODE-RANGE', r'{U}\+[0-9A-Fa-f?]{1,6}(\-[0-9A-Fa-f]{1,6})?'),
     ('IDENT', r'{ident}'),
     ('FUNCTION', r'{ident}\('),