/*--- list.c -- Routines to implement "lists" ------------------
 *
 *  Mark Riordan  25 May 1992.
 *  This code is placed in the public domain.
 */
#include <stdio.h>
#include <ctype.h>
#if !defined(__MACH__) && !defined(MACTC) && !defined(I386BSD) && \
    !defined(apollo)   && !defined(__TURBOC__)  && !defined(mips) /*EWS*/
#include <malloc.h>
#endif
#include <stdlib.h>
#include <string.h>

#define BOOL int

#include "list.h"
#include "listprot.h"
#include "strutilp.h"


/*--- function InitList ----------------------------------------
 *
 *  Initialize a list.
 */
void
InitList(list)
TypList *list;
{
	list->firstptr = list->lastptr = NULL;
}

/*--- function AddToList ------------------------------------
 *
 *  Add an entry to a list.
 *
 *	 Entry:	prevEntry	is the list entry member after which we wish to add
 *								an entry.  If NULL, add to end of list.
 *          entry    	points to a string of bytes we wish to add.
 *				entryLen 	is the number of bytes in the entry.
 *
 *	 Exit:   Returns NULL if successful, else pointer to error message.
 *				Allocates memory for the entry structure and inserts it into the
 *				 list at the desired point.  Memory for the entry data itself
 * 			 is not allocated; the list points directly to "entry".
 */
char *
AddToList(prevEntry,entry,entryLen,list)
TypListEntry *prevEntry;
void         *entry;
unsigned int entryLen;
TypList      *list;
{
	TypListEntry *new_entry;
	
	new_entry = (TypListEntry *) malloc(sizeof *new_entry);
	
	if(!new_entry) return "Can't allocate memory.";
	
	if(prevEntry) {
		new_entry->nextptr = prevEntry->nextptr;
		new_entry->prevptr = prevEntry;
		if(prevEntry->nextptr) {
			prevEntry->nextptr->prevptr = new_entry;
		} else {
			/* There was no next entry, so this is the new last entry. */
			list->lastptr = new_entry;
		}
		prevEntry->nextptr = new_entry;
	} else {
		/* Add to end of list. */
		/* If there's anything on the list, back point this new entry to it. */
		if(list->lastptr) {
			new_entry->prevptr = list->lastptr;
			new_entry->prevptr->nextptr = new_entry;
		} else {
			/* Empty list.  No previous or next entries.
			 * Set beginning of list to this entry.
			 */
			new_entry->prevptr = NULL;
			list->firstptr = new_entry;
		}
		new_entry->nextptr = NULL;
		list->lastptr = new_entry;
	}
	
	new_entry->dataptr = entry;
	new_entry->datalen = entryLen;

	return NULL;
}

/*--- function AppendLineToList ----------------------------------------------
 *
 *  Add a zero-terminated line to the end of a list.
 *
 *  Entry:	line		is a zero-terminated line.
 *				list		points to a list.
 *
 *	 Exit:	We have allocated memory for a copy of the line, and added
 *				 this copy to the end of the list.
 */
char *
AppendLineToList(line,list)
char *line;
TypList *list;
{
	char *lptr;
	
	if(!strcpyalloc(&lptr,line)) return "Can't allocate memory."; 
	return AddToList(NULL,lptr,strlen(lptr)+1,list);
}

/*--- function FreeList ---------------------------------------------------
 *
 *  Free all the entries in a list.
 *
 *  Entry:	list		points to a TypList data structure.
 *
 *	 Exit:	All the entries in the data structure have been freed.
 */
void
FreeList(list)
TypList *list;
{
	TypListEntry *entry, *next_entry;
	
	for(entry=list->firstptr; entry; ) {
		next_entry = entry->nextptr;
		/* Free the data pointed to by this entry. */
		free(entry->dataptr);
		/* Free the entry structure itself. */
		free(entry);
		entry = next_entry;
	}
}

/* Like AddToList, except inserts at the beginning.
 */
char *PrependToList (entry, entryLen, list)
void *entry;
unsigned int entryLen;
TypList *list;
{
  TypListEntry *new_entry;
  
  new_entry = (TypListEntry *)malloc(sizeof (*new_entry));
  
  if (!new_entry)
    return "Can't allocate memory.";
  
  /* If there's anything on the list, point first entry to the new entry. */
  if (list->firstptr) {
    new_entry->nextptr = list->firstptr;
    new_entry->nextptr->prevptr = new_entry;
  } else {
    /* Empty list.  No previous or next entries.
       Set beginning of list to this entry.
     */
    new_entry->nextptr = NULL;
    list->lastptr = new_entry;
  }
  new_entry->prevptr = NULL;
  list->firstptr = new_entry;
  
  new_entry->dataptr = entry;
  new_entry->datalen = entryLen;

  return NULL;
}