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queue.h
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queue.h
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#ifndef LAB0_QUEUE_H
#define LAB0_QUEUE_H
/*
* This program implements a queue supporting both FIFO and LIFO
* operations.
*
* It uses a singly-linked list to represent the set of queue elements
*/
#include <stdbool.h>
#include <stddef.h>
/* Data structure declarations */
/* Linked list element (You shouldn't need to change this) */
typedef struct ELE {
/* Pointer to array holding string.
* This array needs to be explicitly allocated and freed
*/
char *value;
struct ELE *next;
} list_ele_t;
/* Queue structure */
typedef struct {
list_ele_t *head; /* Linked list of elements */
int size;
} queue_t;
/* Operations on queue */
/*
* Create empty queue.
* Return NULL if could not allocate space.
*/
queue_t *q_new();
/*
* Free ALL storage used by queue.
* No effect if q is NULL
*/
void q_free(queue_t *q);
/*
* Attempt to insert element at head of queue.
* Return true if successful.
* Return false if q is NULL or could not allocate space.
* Argument s points to the string to be stored.
* The function must explicitly allocate space and copy the string into it.
*/
bool q_insert_head(queue_t *q, char *s);
/*
* Attempt to insert element at tail of queue.
* Return true if successful.
* Return false if q is NULL or could not allocate space.
* Argument s points to the string to be stored.
* The function must explicitly allocate space and copy the string into it.
*/
bool q_insert_tail(queue_t *q, char *s);
/*
* Attempt to remove element from head of queue.
* Return true if successful.
* Return false if queue is NULL or empty.
* If sp is non-NULL and an element is removed, copy the removed string to *sp
* (up to a maximum of bufsize-1 characters, plus a null terminator.)
* The space used by the list element and the string should be freed.
*/
bool q_remove_head(queue_t *q, char *sp, size_t bufsize);
/*
* Return number of elements in queue.
* Return 0 if q is NULL or empty
*/
int q_size(queue_t *q);
/*
* Reverse elements in queue
* No effect if q is NULL or empty
* This function should not allocate or free any list elements
* (e.g., by calling q_insert_head, q_insert_tail, or q_remove_head).
* It should rearrange the existing ones.
*/
void q_reverse(queue_t *q);
/*
* Sort elements of queue in ascending order
* No effect if q is NULL or empty. In addition, if q has only one
* element, do nothing.
*/
void q_sort(queue_t *q);
#endif /* LAB0_QUEUE_H */