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#include "doubly_linked_list.h"
#include <stdio.h>
#include <stdlib.h>
/**
* The equivalent of a constructor
* to initialize a new node in a doubly linked list.
*
* @param data The data to initialize the head node with.
* @return new Node bound to the data specified
*/
Node *initialize(int data) {
Node *node = malloc(sizeof(Node));
node->data = data;
node->next = NULL;
node->prev = NULL;
return node;
}
/**
* Returns the tail of the list.
*
* @param head The head of the linked list
* @return The tail of the linked list
*/
Node *tail(Node *head) {
Node *tmp = head;
while (tmp) {
if (!tmp->next)
break;
tmp = tmp->next;
}
return tmp;
}
/**
* Adds data to the tail of a doubly linked list.
*
* @param head The head of the doubly linked list
* @param data The data to append to the list
* @return Returns the new node.
*/
Node *add(Node *head, int data) {
Node *t = tail(head);
t->next = initialize(data);
t->next->prev = t;
return t->next;
}
/**
* Returns a specific node in the list by index starting from 0.
*
* @param from The node to start scanning from.
* @param index The zero based index of the node to retrieve.
* @return The node at the specified index.
*/
Node *get(Node *from, int index) {
if (!from || index < 0)
return NULL;
while (index > 0 && from) {
from = from->next;
index--;
}
return from;
}
/**
* Returns the number of items in the linked list.
*
* @param head The head of the linked list
* @return The number of items in the list.
*/
static int size(Node *head) {
int i = 0;
for (Node *tmp = head; tmp && tmp != NULL; tmp = tmp->next)
i++;
return i;
}
/**
* Assigns the next pointer of a node.
*
* @param self The node struct to alter.
* @param other The other node to point to.
*/
static void assign_next(Node *self, Node *other) {
if (self)
self->next = other;
if (other)
other->prev = self;
}
/**
* Assigns the previous pointer of a node.
*
* @param self The node struct to alter.
* @param other The other node to point to.
*/
static void assign_prev(Node *self, Node *other) {
if (self)
self->prev = other;
if (other)
other->next = self;
}
/**
* Swaps two different nodes in the same linked list.
*
* @param x A node to swap
* @param y Another node to swap
*/
void swap(Node *x, Node *y) {
if (x == y)
return;
if (!x || !y)
return;
if (x->prev == y && y->next == x)
return swap(y, x);
Node *xp = x->prev, *xn = x->next, *yp = y->prev, *yn = y->next;
// if adjacent
if (x->next == y && y->prev == x) {
assign_next(x, yn);
assign_prev(x, y);
assign_prev(y, xp);
} else {
assign_prev(x, yp);
assign_next(x, yn);
assign_prev(y, xp);
assign_next(y, xn);
}
}
/**
* Prints the previous, data and next pointers for a node
*
* @param node The node to print
*/
static void print(Node *node) {
if (node->prev && node->next)
printf("(%d<%d>%d)", node->prev->data, node->data, node->next->data);
else if (node->next)
printf("(nil<%d>%d)", node->data, node->next->data);
else
printf("(%d<%d>nil)", node->prev->data, node->data);
printf(" ");
}
/**
* Iterates through each node in a linked list.
*
* @param self The node to start iterating from.
* @param block The callback function to invoke on each node.
*/
void each(Node *self, Visitor block) {
Node *tmp = self;
while (tmp) {
block(tmp);
tmp = tmp->next;
}
}
/**
* Renders a visual output of a full linked list.
*
* @param node The head of the linked list
*/
void inspect(Node *node) {
printf("[ ");
each(node, &print);
printf("]\n");
}
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