xmd Code

/*
llist2.h
	- Header file for an implementation of a dynamically
	allocated linked list.
	- Each node of the list contains 2 data elements and links to
	previous and next nodes in the list.
	- The list itself consists of links to the first (head) and
	last (tail) nodes in the list, an error message, and a flag
	for whether the list is closed or not (whether there are any 
	NULL links in the list).
Created By:  David G. Clark
Last Modified:  06/23/97
*/

/*
Defines
*/
#ifndef BOOLEAN
#define BOOLEAN int
#define TRUE 1
#define FALSE 0
#define UNDEF -1
#endif

#define InfoType_t int

/*
Structure Definitions
*/
typedef enum {
	NoErr,
	MemErr,
	NullErr,
	ClosedErr
	} ErrorCode_t;

typedef struct LNode_t {
	struct LNode_t *Next;
	struct LNode_t *Prev;
	InfoType_t      Mark;
	long            Step;
	} ListNode_t;

typedef ListNode_t *Link_t;

typedef struct {
	Link_t      Head;
	Link_t      Tail;
	ErrorCode_t Error;
	BOOLEAN     Closed;
	} LinkList_t;

/*
Linked List Function Headers
*/
void InitList(LinkList_t *list);
/* Sets Head and Tail to NULL, Error to NoErr,
	and Closed to FALSE. */

BOOLEAN IsListError(LinkList_t list);
/* Returns FALSE if Error is NoErr, and
	TRUE otherwise. */

void PrintListError(FILE *output, LinkList_t list);
/* Prints error specific messages to output using
	a switch (list.Error) statement. */

BOOLEAN AddNodeToList(LinkList_t *list, InfoType_t pos, long step);
/* If list is closed or not enough memory to allocate
	a new node, returns FALSE.  Otherwise, creates a new
	node, copies the data elem into it, links to the
	end of the list, and returns TRUE. */

BOOLEAN RemLastNodeFromList(LinkList_t *list);
/* If list is closed or null, returns FALSE.  Otherwise,
	removes the last node from the list, updating the
	appropriate links, and returns TRUE. */

BOOLEAN RemFirstNodeFromList(LinkList_t *list);
/* If list is closed or null, returns FALSE.  Otherwise,
	removes the first node from the list, updating the
	appropriate links, and returns TRUE. */

int ListLength(LinkList_t list);
/* Returns the length (number of nodes) in
	the list as an integer. */

void FreeList(LinkList_t *list);
/* Parses through the list, freeing the memory
	used by every node until done.  Calls OpenList. */

void CloseList(LinkList_t *list);
/* Links list->Head to list->Tail and sets
	list->Closed to TRUE. */

void OpenList(LinkList_t *list);
/* Sets list->Head->Prev and list->Tail->Next to NULL,
	and list->Closed to FALSE. */

void PrintList(FILE *output, LinkList_t list);
/* Parses through the list, printing the data
	contained in each node to output.  Very
	primitive, must be changed if InfoType_t
	is changed. */