a bit better call stack

ml.h

@@ -1,6 +1,5 @@
 #pragma once
 
-
 #include <map>
 #include <string>
 #include <vector>
@@ -94,6 +93,8 @@ private:
 // and the environment to run the function in.
 typedef MlValue (*Builtin)(std::vector<MlValue>, MlEnvironment &);
 
+// friend class
+class MlPerfMon;
 
 class MlValue {
 public:
@@ -140,29 +141,15 @@ public:
     MlValue eval(MlEnvironment &env);
 
     bool is_builtin() const;
-
     bool is_number() const;
-
     bool is_string() const;
-
     bool is_list() const;
 
-    // Get the boolean value of this value.
     bool as_bool() const;
-
-    // Get this item's integer value
     long as_int() const;
-
-    // Get this item's floating point value
     double as_float() const;
-
-    // Get this item's string value
     std::string as_string() const;
-
-    // Get this item's atom value
     std::string as_atom() const;
-
-    // Get this item's list value
     std::vector<MlValue> as_list() const;
 
     // Push an item to the end of this list
@@ -172,13 +159,8 @@ public:
     MlValue pop();
 
 
-    // Cast this to an integer value
     MlValue cast_to_int() const;
-
-    // Cast this to a floating point value
     MlValue cast_to_float() const;
-
-    // Cast this to a string
     MlValue cast_to_string() const;
 
 
@@ -207,24 +189,26 @@ public:
 
 private:
     enum {
-	QUOTE,
-	ATOM,
-	INT,
-	FLOAT,
-	LIST,
-	STRING,
-	LAMBDA,
-	BUILTIN,
-	NIL
+        QUOTE,
+        ATOM,
+        INT,
+        FLOAT,
+        LIST,
+        STRING,
+        LAMBDA,
+        BUILTIN,
+        NIL
     } type;
 
     union {
-	long i;
-	double f;
-	Builtin b;
+        long i;
+        double f;
+        Builtin b;
     } stack_data;
 
     std::string str;
     std::vector<MlValue> list;
     MlEnvironment lambda_scope;
+
+    friend class MlPerfMon;
 };