Implemented "unit".

basic.scss

@@ -67,4 +67,8 @@ div {
   a: type-of(false);
   b: type-of("true");
   c: type-of(a b c);
+  
+  a: unit(10);
+  b: unit(10%);
+  c: unit(10boo);
 }

context.cpp

@@ -64,7 +64,7 @@ namespace Sass {
     register_function(join_3_descriptor, join_3);
     // Introspection Functions
     register_function(type_of_descriptor, type_of);
-    // register_function(unit_descriptor, unit);
+    register_function(unit_descriptor, unit);
     // register_function(unitless_descriptor, unitless);
     // register_function(comparable_descriptor, comparable);
   }

functions.cpp

+#ifndef SASS_PRELEXER_INCLUDED
+#include "prelexer.hpp"
+#endif
 #include "functions.hpp"
 #include <iostream>
 #include <cmath>
@@ -339,6 +342,31 @@ namespace Sass {
       return type;
     }
     
+    extern const char empty_str[] = "";
+    extern const char percent_str[] = "%";
+    
+    Function_Descriptor unit_descriptor =
+    { "unit", "$value", 0 };
+    Node unit(const vector<Token>& parameters, map<Token, Node>& bindings) {
+      Node val(bindings[parameters[0]]);
+      Node u(Node::string_constant, val.line_number, Token::make());
+      switch (val.type)
+      {
+        case Node::number:
+          u.content.token = Token::make(empty_str);
+          break;
+        case Node::numeric_percentage:
+          u.content.token = Token::make(percent_str);
+          break;
+        case Node::numeric_dimension:
+          u.content.token = Token::make(val.content.dimension.unit, Prelexer::identifier(val.content.dimension.unit));
+          break;
+        default: // TO DO: throw an exception
+          u.content.token = Token::make(empty_str);
+          break;
+      }
+      return u;
+    }
       
     
     

functions.hpp

@@ -133,8 +133,8 @@ namespace Sass {
     extern Function_Descriptor type_of_descriptor;
     Node type_of(const vector<Token>& parameters, map<Token, Node>& bindings);
 
-    // extern Function_Descriptor unit_descriptor;
-    // Node unit(const vector<Token>& parameters, map<Token, Node>& bindings);
+    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);

prelexer.hpp

+#define SASS_PRELEXER_INCLUDED
+
 namespace Sass {
   namespace Prelexer {
 

values.hpp

 #include <string>
 #include <sstream>
 #include <cstring>
+
+#ifndef SASS_PRELEXER_INCLUDED
 #include "prelexer.hpp"
+#endif
 
 namespace Sass {
   using std::string;