Support stand-alone negation in selector grammar

Previously negation was only supported as the right hand side
of an composite.

spec/app/text-mate-scope-selector-spec.coffee

@@ -28,6 +28,8 @@ describe "TextMateScopeSelector", ->
 
     it "matches negation", ->
       expect(new TextMateScopeSelector('a - c').matches(['a', 'b'])).toBeTruthy()
+      expect(new TextMateScopeSelector('-c').matches(['b'])).toBeTruthy()
+      expect(new TextMateScopeSelector('-c').matches(['c', 'b'])).toBeFalsy()
       expect(new TextMateScopeSelector('a-b').matches(['a', 'b'])).toBeFalsy()
       expect(new TextMateScopeSelector('a -b').matches(['a', 'b'])).toBeFalsy()
       expect(new TextMateScopeSelector('a -c').matches(['a', 'b'])).toBeTruthy()
@@ -37,6 +39,8 @@ describe "TextMateScopeSelector", ->
       expect(new TextMateScopeSelector('a & b').matches(['b', 'a'])).toBeTruthy()
       expect(new TextMateScopeSelector('a&b&c').matches(['c'])).toBeFalsy()
       expect(new TextMateScopeSelector('a&b&c').matches(['a', 'b', 'd'])).toBeFalsy()
+      expect(new TextMateScopeSelector('a & -b').matches(['a', 'b', 'd'])).toBeFalsy()
+      expect(new TextMateScopeSelector('a & -b').matches(['a', 'd'])).toBeTruthy()
 
     it "matches composites", ->
       expect(new TextMateScopeSelector('a,b,c').matches(['b', 'c'])).toBeTruthy()

src/app/text-mate-scope-selector-matchers.coffee

@@ -72,20 +72,20 @@ class AndMatcher
     "#{@left.toCssSelector()} #{@right.toCssSelector()}"
 
 class NegateMatcher
-  constructor: (@left, @right) ->
+  constructor: (@matcher) ->
 
   matches: (scopes) ->
-    @left.matches(scopes) and not @right.matches(scopes)
+    not @matcher.matches(scopes)
 
   toCssSelector: ->
-    "#{@left.toCssSelector()} :not(#{@right.toCssSelector()})"
+    ":not(#{@matcher.toCssSelector()})"
 
 class CompositeMatcher
   constructor: (left, operator, right) ->
     switch operator
       when '|' then @matcher = new OrMatcher(left, right)
       when '&' then @matcher = new AndMatcher(left, right)
-      when '-' then @matcher = new NegateMatcher(left, right)
+      when '-' then @matcher = new AndMatcher(left, new NegateMatcher(right))
 
   matches: (scopes) ->
     @matcher.matches(scopes)

src/app/text-mate-scope-selector-pattern.pegjs

@@ -25,15 +25,26 @@ path
     return new matchers.PathMatcher(first, others);
   }
 
-expression
-  = path
-
-  / "(" _ selector:selector _ ")" {
+group
+  = "(" _ selector:selector _ ")" {
     return selector;
   }
 
+expression
+  = "-" _ group:group _ {
+    return new matchers.NegateMatcher(group);
+  }
+
+  / "-" _ path:path _ {
+    return new matchers.NegateMatcher(path);
+  }
+
+  / group
+
+  / path
+
 composite
-  = left:expression  _ operator:[|&-] _ right:composite {
+  = left:expression _ operator:[|&-] _ right:composite {
     return new matchers.CompositeMatcher(left, operator, right);
   }