Moving the environment definition into its own file so I can eliminate a circular dependency.

context.hpp

 #define SASS_CONTEXT
 
+#ifndef SASS_ENVIRONMENT
+#include "environment.hpp"
+#endif
 
 #include <utility>
-#include <map>
 #include "node_factory.hpp"
 #include "functions.hpp"
 
@@ -10,35 +12,35 @@ namespace Sass {
   using std::pair;
   using std::map;
   
-  struct Environment {
-    map<Token, Node> current_frame;
-    Environment* parent;
-    Environment* global;
+  // struct Environment {
+  //   map<Token, Node> current_frame;
+  //   Environment* parent;
+  //   Environment* global;
     
-    Environment()
-    : current_frame(map<Token, Node>()), parent(0), global(0)
-    { }
+  //   Environment()
+  //   : current_frame(map<Token, Node>()), parent(0), global(0)
+  //   { }
     
-    void link(Environment& env)
-    {
-      parent = &env;
-      global = parent->global ? parent->global : parent;
-    }
+  //   void link(Environment& env)
+  //   {
+  //     parent = &env;
+  //     global = parent->global ? parent->global : parent;
+  //   }
     
-    bool query(const Token& key) const
-    {
-      if (current_frame.count(key)) return true;
-      else if (parent)              return parent->query(key);
-      else                          return false;
-    }
+  //   bool query(const Token& key) const
+  //   {
+  //     if (current_frame.count(key)) return true;
+  //     else if (parent)              return parent->query(key);
+  //     else                          return false;
+  //   }
     
-    Node& operator[](const Token& key)
-    {
-      if (current_frame.count(key)) return current_frame[key];
-      else if (parent)              return (*parent)[key];
-      else                          return current_frame[key];
-    }
-  };
+  //   Node& operator[](const Token& key)
+  //   {
+  //     if (current_frame.count(key)) return current_frame[key];
+  //     else if (parent)              return (*parent)[key];
+  //     else                          return current_frame[key];
+  //   }
+  // };
 
   struct Context {
     Environment global_env;

environment.hpp

+#define SASS_ENVIRONMENT
+
+#include <map>
+
+#ifndef SASS_NODE
+#include "node.hpp"
+#endif
+
+namespace Sass {
+  using std::map;
+
+  struct Environment {
+    map<Token, Node> current_frame;
+    Environment* parent;
+    Environment* global;
+    
+    Environment()
+    : current_frame(map<Token, Node>()), parent(0), global(0)
+    { }
+    
+    void link(Environment& env)
+    {
+      parent = &env;
+      global = parent->global ? parent->global : parent;
+    }
+    
+    bool query(const Token& key) const
+    {
+      if (current_frame.count(key)) return true;
+      else if (parent)              return parent->query(key);
+      else                          return false;
+    }
+    
+    Node& operator[](const Token& key)
+    {
+      if (current_frame.count(key)) return current_frame[key];
+      else if (parent)              return (*parent)[key];
+      else                          return current_frame[key];
+    }
+  };
+}
\ No newline at end of file