Add support for == and ~= in SassScript.

lib/sass/constant.rb

@@ -33,6 +33,7 @@ module Sass
       ?~ => :not,
       ?& => :single_and,
       ?| => :single_or,
+      ?= => :single_equals,
       CONSTANT_CHAR => :const,
       STRING_CHAR => :str,
       ESCAPE_CHAR => :esc
@@ -137,17 +138,22 @@ module Sass
               end
 
               # Time for a unary op!
-              if ![nil, :open, :close, :const, :single_and, :single_or].include?(symbol) && beginning_of_token
+              if ![nil, :open, :close, :const, :single_and, :single_or, :single_equals].include?(symbol) && beginning_of_token
                 beginning_of_token = true
                 to_return << :unary << symbol
                 next
               end
 
-              if (symbol == :single_and || symbol == :single_or) && last == symbol
+              if [:single_and, :single_or, :single_equals].include?(symbol) && last == symbol
                 to_return[-1] = symbol.to_s.gsub(/^single_/, '').to_sym
                 next
               end
 
+              if symbol == :single_equals && last == :not
+                to_return[-1] = :not_equals
+                next
+              end
+
               # Are we looking at an operator?
               if symbol && (symbol != :mod || str.empty?)
                 str = reset_str.call

lib/sass/constant/literal.rb

@@ -53,6 +53,14 @@ class Sass::Constant::Literal # :nodoc:
     to_bool ? self : other
   end
 
+  def equals(other)
+    Sass::Constant::Bool.from_value(self.class == other.class && self.value == other.value)
+  end
+
+  def not_equals(other)
+    Sass::Constant::Bool.from_value(!equals(other).to_bool)
+  end
+
   def unary_not
     Sass::Constant::Bool.from_value(!to_bool)
   end

lib/sass/constant/number.rb

@@ -59,6 +59,10 @@ module Sass::Constant
       end
     end
 
+    def equals(other)
+      Sass::Constant::Bool.from_value(super.to_bool && self.unit == other.unit)
+    end
+
     def to_s
       value = @value
       value = value.to_i if value % 1 == 0.0

lib/sass/constant/operation.rb

@@ -9,6 +9,7 @@ module Sass::Constant
     def initialize(operand1, operand2, operator)
       raise Sass::SyntaxError.new("SassScript doesn't support a single-& operator.") if operator == :single_and
       raise Sass::SyntaxError.new("SassScript doesn't support a single-| operator.") if operator == :single_or
+      raise Sass::SyntaxError.new("SassScript doesn't support a single-= operator.") if operator == :single_equals
 
       @operand1 = operand1
       @operand2 = operand2

test/sass/engine_test.rb

@@ -434,6 +434,26 @@ a
 SASS
   end
 
+  def test_equals
+    assert_equal(<<CSS, render(<<SASS))
+a {
+  t1: true;
+  t2: true;
+  t3: true;
+  f1: false;
+  f2: false;
+  f3: false; }
+CSS
+a
+  t1 = "foo" == foo
+  t2 = 1 == 1.0
+  t3 = false ~= true
+  f1 = foo == bar
+  f2 = 1em == 1px
+  f3 = 12 ~= 12
+SASS
+  end
+
   def test_argument_error
     assert_raise(Sass::SyntaxError) { render("a\n  b = hsl(1)") }
   end