[Sass] [SCSS] Add support for declaring variables.

No way to use them as of yet.

lib/sass/script/lexer.rb

@@ -43,6 +43,7 @@ module Sass
         '<' => :lt,
         '#{' => :begin_interpolation,
         '}' => :end_interpolation,
+        ';' => :semicolon,
       }
 
       # A list of operator strings ordered with longer names first
@@ -113,6 +114,12 @@ module Sass
         @tok ||= read_token
       end
 
+      # Rewinds the underlying StringScanner
+      # to before the token returned by \{#peek}.
+      def unpeek!
+        @scanner.pos -= @scanner.matched_size if @tok
+      end
+
       # @return [Boolean] Whether or not there's more source text to lex.
       def done?
         whitespace unless after_interpolation?

lib/sass/script/parser.rb

@@ -42,6 +42,19 @@ module Sass
         expr
       end
 
+      # Parses a single SassScript expression.
+      # Unlike \{#parse}, doesn't expect this expression
+      # to consume the entire input stream.
+      #
+      # @return [Script::Node] The root node of the parse tree
+      # @raise [Sass::SyntaxError] if the expression isn't valid SassScript
+      def parse_some
+        expr = assert_expr :expr
+        expr.options = @options
+        @lexer.unpeek!
+        expr
+      end
+
       # Parses the argument list for a mixin include.
       #
       # @return [Array<Script::Node>] The root nodes of the arguments.

lib/sass/scss/parser.rb

@@ -73,6 +73,23 @@ module Sass
         node
       end
 
+      def variable
+        return unless raw '!'
+        name = tok! IDENT
+        ss
+
+        if raw '|'
+          raw! '|'
+          guarded = true
+        end
+
+        raw! '='
+        ss
+        expr = sass_script_parser.parse_some
+
+        node(Sass::Tree::VariableNode.new(name, expr, guarded))
+      end
+
       def operator
         # Many of these operators (all except / and ,)
         # are disallowed by the CSS spec,
@@ -115,14 +132,18 @@ module Sass
       # A block may contain declarations and/or rulesets
       def block_contents(node)
         block_given? ? yield : ss
-        node << (child = directive || declaration_or_ruleset)
+        node << (child = block_child)
         while raw(';') || (child && !child.children.empty?)
           block_given? ? yield : ss
-          node << (child = directive || declaration_or_ruleset)
+          node << (child = block_child)
         end
         node
       end
 
+      def block_child
+        variable || directive || declaration_or_ruleset
+      end
+
       # This is a nasty hack, and the only place in the parser
       # that requires backtracking.
       # The reason is that we can't figure out if certain strings
@@ -324,6 +345,11 @@ module Sass
         node
       end
 
+      def sass_script_parser
+        Sass::Script::Parser.new(@scanner, @line,
+          @scanner.pos - @scanner.string.rindex("\n"))
+      end
+
       EXPR_NAMES = {
         :medium => "medium (e.g. print, screen)",
         :pseudo_expr => "expression (e.g. fr, 2n+1)",