Implemented the "unitless" builtin.

basic.scss

@@ -71,6 +71,8 @@ div {
   a: unit(10);
   b: unit(10%);
   c: unit(10boo);
+  d: unitless(20%);
+  e: unitless(123);
   
   a: hsl(23, 100%, 50%);
   b: hsl(120, 100%, 50%);

context.cpp

@@ -73,7 +73,7 @@ namespace Sass {
     // Introspection Functions
     register_function(type_of_descriptor, type_of);
     register_function(unit_descriptor, unit);
-    // register_function(unitless_descriptor, unitless);
+    register_function(unitless_descriptor, unitless);
     // register_function(comparable_descriptor, comparable);
   }
   

functions.cpp

@@ -416,7 +416,30 @@ namespace Sass {
       return u;
     }
 
+    extern const char true_str[]  = "true";
+    extern const char false_str[] = "false";
 
+    Function_Descriptor unitless_descriptor =
+    { "unitless", "$value", 0 };
+    Node unitless(const vector<Token>& parameters, map<Token, Node>& bindings) {
+      Node val(bindings[parameters[0]]);
+      Node result(Node::string_constant, val.line_number, Token::make());
+      result.unquoted = true;
+      switch (val.type)
+      {
+        case Node::number:
+          result.content.token = Token::make(true_str);
+          break;
+        case Node::numeric_percentage:
+        case Node::numeric_dimension:
+          result.content.token = Token::make(false_str);
+          break;
+        default:
+          // TO DO: throw an exception;
+          break;
+      }
+      return result;
+    }
     
     
     

functions.hpp

@@ -141,10 +141,10 @@ namespace Sass {
 
     extern Function_Descriptor unit_descriptor;
     Node unit(const vector<Token>& parameters, map<Token, Node>& bindings);
-    // 
-    // extern Function_Descriptor unitless_descriptor;    
-    // Node unitless(const vector<Token>& parameters, map<Token, Node>& bindings);
-    // 
+    
+    extern Function_Descriptor unitless_descriptor;    
+    Node unitless(const vector<Token>& parameters, map<Token, Node>& bindings);
+    
     // extern Function_Descriptor comparable_descriptor;    
     // Node comparable(const vector<Token>& parameters, map<Token, Node>& bindings);