#ifndef _fifo_tmpl
#define _fifo_tmpl

/* This file implements a FIFO structure for arbitrary data types */

/* Usage:
	new Fifo<ITEM>;
	Fifo->Push(ITEM *);
	fifosize = Fifo->Size();
	itemptr = Fifo->Pull();
*/

template <class ITEM>
class Fifo {

public:
	Fifo() {
		head = NULL;
		tail = NULL;
		size = 0;
	}
	virtual ~Fifo() {
		while ( Pull() )
			;
	}

	virtual void Push(ITEM *item) {
		if ( tail ) {
			tail->next = new element;
			tail = tail->next;
		} else {
			tail = new element;
			if ( ! head )
				head = tail;
		}
		tail->next = NULL;
		tail->item = item;
		++size;
		return;
	}
	virtual ITEM *Peek(void) {
		return(head ? head->item : (ITEM *)0);
	}
	virtual ITEM *Pull(void) {
		element *tmp;
		ITEM *item;

		/* Don't pull on a tired head */
		if ( ! head )
			return(NULL);

		/* Pull off the top! */
		tmp = head;
		if ( head == tail ) {
			head = tail = NULL;
		} else {
			head = head->next;
		}
		item = tmp->item;
		delete tmp;
		--size;
		return(item);
	}
	virtual int Size(void) {
		return(size);
	}

protected:
	int	size;
	typedef struct element {
		ITEM *item;
		struct element *next;
	} element;
	element *head, *tail;
};


#endif /* _fifo_tmpl */