// inserts at the specified index.
// example: insert(2) would be third item in the list.
int ListInsertAt( list *l, void *data, int pos ) {
if ( l == NULL || data == NULL )
return 0;
listNode *node = l->head;
if ( pos <= 0 ) {
ListInsertAtFront( l, data );
return 1;
}
else if ( pos > l->itemCount ) {
ListInsertAtEnd( l, data );
return 1;
}
for( int i = 0; i < l->itemCount; i++ ) {
if ( i == pos ) {
listNode *prev = node->prev;
listNode *newNode = ListCreateNode( data );
node->prev = newNode; // insert before this.
prev->next = newNode; // tell prev node this new node follows it.
newNode->prev = prev;
newNode->next = node;
l->itemCount++;
}
node = node->next;
}
return 1;
}
void ListInsert(ListNode *Node, void *Data)
{
while (Node->Next != NULL)
Node = Node->Next;
Node->Next = ListCreateNode();
(Node->Next)->Prev = Node;
Node = Node->Next;
Node->Data = Data;
Node->Next = NULL;
}
list *ListCreate( void *data ) {
list *l = malloc( sizeof ( list ) );
listNode *node = ListCreateNode( data );
// single item right
node->next = node;
node->prev = node;
// update list ptrs.
l->head = node;
l->tail = node;
l->itemCount = 1;
return l;
}
// inserts as head
int ListInsertAtFront( list *l, void *data ) {
if ( l == NULL || data == NULL )
return 0;
listNode *node = ListCreateNode( data );
node->prev = l->tail;
node->next = l->head;
l->head->prev = node;
l->head = node;
l->itemCount++;
return 1;
}
// inserts as tail
int ListInsertAtEnd( list *l, void *data ) {
if ( l == NULL || data == NULL )
return 0;
listNode *node = ListCreateNode( data );
node->prev = l->tail; // adding to end so tail is before this
node->next = l->head; // circally doubly linked list
l->tail->next = node; // current tail points to this new node
l->tail = node; // set tail ptr to this new node.
l->itemCount++;
return 1;
}
