/*
* DoublyLinkedList - A doubly linked list to contain values of type E which
* can be cast from any other primitive type.
*
* Created on: Feb 24, 2009
* Author: Yama H
*/
/*
* E's are long doubles because they allocate the most space of all primitive
* types, therefore ensuring enough space for any other type that could be
* cast into it.
*/
typedef long double E;
/*
* A DLLNode (DoublyLinkedListNode) consists of a piece of data of type E
* (which is really usually some other type cast into an E, and can also be a
* pointer) and pointers to the next and previous DLLNodes in the list (NULL
* if the node is a head or tail node.
*/
typedef struct
{
E data;
void* next;
void* prev;
}DLLNode;
/*
* A DoublyLinkedList is just a head Node, a pointer to a tail node, and an int
* representing the amount of elements in the list. The head node is not a
* pointer because it's value never changes unless the list is emptied.
*/
typedef struct
{
DLLNode head; // the head isn't a pointer, but the tail is,
DLLNode* tail; // because the head is static and the tail is dynamic
int elements;
}DoublyLinkedList;
/*
* Initializes List and creates first node.
*/
void DoublyLinkedList_initialize(DoublyLinkedList* dll, E data);
/*
* Initializes an empty List.
*/
void DoublyLinkedList_init(DoublyLinkedList* dll);
/*
* Retrieves the data from the node passed.
*/
E DoublyLinkedList_getData(DLLNode node);
/*
* Retrives the node after the current node. Returns the parameter if the
* current node is the last entry (the tail).
*/
DLLNode DoublyLinkedList_getNext(DLLNode node);
/*
* Retrieves the node before the current node. Returns the parameter if the
* current node is the first entry (the head).
*/
DLLNode DoublyLinkedList_getPrev(DLLNode node);
/*
* Sets the data in a specified node in the list to a specified value, and
* updates the node passed in. Nonzero on failure.
*/
int DoublyLinkedList_setData(DoublyLinkedList* dll, DLLNode* node, E data);
/*
* Adds an entry to the List.
*/
void DoublyLinkedList_addEntry(DoublyLinkedList* dll, E data);
/*
* Removes an entry from the list. Nonzero if list is empty.
*/
int DoublyLinkedList_removeEntry(DoublyLinkedList* dll);
/*
* Retrieves the head node.
*/
DLLNode DoublyLinkedList_getHead(DoublyLinkedList* dll);
/*
* Retrieves the tail node.
*/
DLLNode DoublyLinkedList_getTail(DoublyLinkedList* dll);
/*
* Returns 1 if node1 is identical to node2 and 0 if not.
*/
int DoublyLinkedList_equals(DLLNode node1, DLLNode node2);
/*
* Returns the number of elements currently in the list.
*/
int DoublyLinkedList_getElements(DoublyLinkedList* dll);
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