[Sass] [SCSS] Support empty directives and rules.

lib/sass/scss/parser.rb

@@ -83,6 +83,7 @@ module Sass
         node = node(Sass::Tree::DirectiveNode.new("@#{name} #{val}".strip))
 
         if tok(/\{/)
+          node.has_children = true
           block_contents(node, :directive)
           tok!(/\}/)
         end
@@ -232,6 +233,7 @@ module Sass
       end
 
       def block(node, context)
+        node.has_children = true
         tok!(/\{/)
         block_contents(node, context)
         tok!(/\}/)
@@ -242,7 +244,7 @@ module Sass
       def block_contents(node, context)
         block_given? ? yield : ss_comments(node)
         node << (child = block_child(context))
-        while tok(/;/) || (child && !child.children.empty?)
+        while tok(/;/) || (child && child.has_children)
           block_given? ? yield : ss_comments(node)
           node << (child = block_child(context))
         end

lib/sass/tree/directive_node.rb

@@ -27,44 +27,42 @@ module Sass::Tree
     # @param tabs [Fixnum] The level of indentation for the CSS
     # @return [String] The resulting CSS
     def _to_s(tabs)
-      if children.empty?
-        value + ";"
-      else
-        result = if style == :compressed
-                   "#{value}{"
-                 else
-                   "#{'  ' * (tabs - 1)}#{value} {" + (style == :compact ? ' ' : "\n")
-                 end
-        was_prop = false
-        first = true
-        children.each do |child|
-          next if child.invisible?
-          if style == :compact
-            if child.is_a?(PropNode)
-              result << "#{child.to_s(first || was_prop ? 1 : tabs + 1)} "
-            else
-              if was_prop
-                result[-1] = "\n"
-              end
-              rendered = child.to_s(tabs + 1).dup
-              rendered = rendered.lstrip if first
-              result << rendered.rstrip + "\n"
-            end
-            was_prop = child.is_a?(PropNode)
-            first = false
-          elsif style == :compressed
-            result << (was_prop ? ";#{child.to_s(1)}" : child.to_s(1))
-            was_prop = child.is_a?(PropNode)
+      return value + ";" unless has_children
+      return value + " {}" if children.empty?
+      result = if style == :compressed
+                 "#{value}{"
+               else
+                 "#{'  ' * (tabs - 1)}#{value} {" + (style == :compact ? ' ' : "\n")
+               end
+      was_prop = false
+      first = true
+      children.each do |child|
+        next if child.invisible?
+        if style == :compact
+          if child.is_a?(PropNode)
+            result << "#{child.to_s(first || was_prop ? 1 : tabs + 1)} "
           else
-            result << child.to_s(tabs + 1) + "\n"
+            if was_prop
+              result[-1] = "\n"
+            end
+            rendered = child.to_s(tabs + 1).dup
+            rendered = rendered.lstrip if first
+            result << rendered.rstrip + "\n"
           end
+          was_prop = child.is_a?(PropNode)
+          first = false
+        elsif style == :compressed
+          result << (was_prop ? ";#{child.to_s(1)}" : child.to_s(1))
+          was_prop = child.is_a?(PropNode)
+        else
+          result << child.to_s(tabs + 1) + "\n"
         end
-        result.rstrip + if style == :compressed
-                          "}"
-                        else
-                          (style == :expanded ? "\n" : " ") + "}\n"
-                        end
       end
+      result.rstrip + if style == :compressed
+                        "}"
+                      else
+                        (style == :expanded ? "\n" : " ") + "}\n"
+                      end
     end
   end
 end

lib/sass/tree/node.rb

@@ -33,6 +33,13 @@ module Sass
       # @return [Array<Tree::Node>]
       attr_accessor :children
 
+      # Whether or not this node has child nodes.
+      # This may be true even when \{#children} is empty,
+      # in which case this node has an empty block (e.g. `{}`).
+      #
+      # @return [Boolean]
+      attr_accessor :has_children
+
       # The line of the document on which this node appeared.
       #
       # @return [Fixnum]
@@ -62,6 +69,12 @@ module Sass
         @options = options
       end
 
+      # @private
+      def children=(children)
+        self.has_children ||= !children.empty?
+        @children = children
+      end
+
       # The name of the document on which this node appeared.
       #
       # @return [String]

test/sass/scss/css_test.rb

@@ -21,6 +21,14 @@ sel {
 CSS
   end
 
+  def test_empty_rule
+    assert_equal "", render("#foo .bar {}")
+    assert_equal "", render(<<SCSS)
+#foo .bar {
+}
+SCSS
+  end
+
   def test_cdo_and_cdc_ignored_at_toplevel
     assert_equal <<CSS, render(<<SCSS)
 foo {
@@ -396,13 +404,13 @@ SCSS
 SCSS
   end
 
-  # TODO: Make this work.
-  #   Currently we check whether a directive has children
-  #   to determine whether to use {} or ;.
-  #
-  # def test_empty_block_directive
-  #   assert_parses "@foo {}"
-  # end
+  def test_empty_block_directive
+    assert_parses "@foo {}"
+    assert_equal "@foo {}\n", render(<<SCSS)
+@foo {
+}
+SCSS
+  end
 
   def test_multiple_block_directives
     assert_parses <<SCSS