/*  An implementation of a Counter class written in C.
 *  Author:  Mark A. Sheldon
 *  Copyright:  March 2008
 */

/*
 *  Types for classes.  
 *  A class is a kind of object.  Need to clean it up more:
 *    o add field for superclass
 *    o make operations take a first parameter, like this in regular object, but
 *      then the operations will ignore it.
 *    o Add private and public class variables (besides the special name field).
 */

typedef struct counter_class {
	const char *name;
	struct counter_class_ops *ops;
} *counter_class_t;  

struct counter_class_ops {
	struct counter_instance *(*new) (int initial_value);
};

/*
 *  Types for instances.
 *  Need to do or resolve:
 *    o public instance variables should go directly in struct or in a
 *      contained struct?
 *    o Do another version that does dynamic dispatch so we can get 
 *      inheritance
 */

typedef struct counter_instance {
	void *private;
	counter_class_t class;
	struct counter_instance_ops *ops;
} *counter_t;

typedef counter_t Counter;

struct counter_instance_ops {
	int  (*value)        (counter_t this);
	void (*increment)    (counter_t this);
	void (*increment_by) (counter_t this, int n);
	void (*decrement)    (counter_t this);
	void (*decrement_by) (counter_t this, int n);
	void (*reset)        (counter_t this);
	BOOL  (*equals)      (counter_t this, counter_t c);
	void (*destroy)      (counter_t this);
};

counter_class_t CounterClass;