queue.h File Reference

Double-ended queue. More...

Defines
#define	QUEUE_NULL   ((void *) 0)
	A null QueueValue.
Typedefs
typedef struct _Queue	Queue
	A double-ended queue.
typedef void *	QueueValue
	A value stored in a Queue.
Functions
Queue *	queue_new (void)
	Create a new double-ended queue.
void	queue_free (Queue *queue)
	Destroy a queue.
int	queue_push_head (Queue *queue, QueueValue data)
	Add a value to the head of a queue.
QueueValue	queue_pop_head (Queue *queue)
	Remove a value from the head of a queue.
QueueValue	queue_peek_head (Queue *queue)
	Read value from the head of a queue, without removing it from the queue.
int	queue_push_tail (Queue *queue, QueueValue data)
	Add a value to the tail of a queue.
QueueValue	queue_pop_tail (Queue *queue)
	Remove a value from the tail of a queue.
QueueValue	queue_peek_tail (Queue *queue)
	Read a value from the tail of a queue, without removing it from the queue.
int	queue_is_empty (Queue *queue)
	Query if any values are currently in a queue.

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Detailed Description

Double-ended queue.

A double ended queue stores a list of values in order. New values can be added and removed from either end of the queue.

To create a new queue, use queue_new. To destroy a queue, use queue_free.

To add values to a queue, use queue_push_head and queue_push_tail.

To read values from the ends of a queue, use queue_pop_head and queue_pop_tail. To examine the ends without removing values from the queue, use queue_peek_head and queue_peek_tail.

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Function Documentation

void queue_free

(

Queue *

queue

)

Destroy a queue.

Parameters:

queue

The queue to destroy.

int queue_is_empty

(

Queue *

queue

)

Query if any values are currently in a queue.

Parameters:

queue

The queue.

Returns:

Zero if the queue is not empty, non-zero if the queue is empty.

Queue* queue_new

(

void

)

Create a new double-ended queue.

Returns:

A new queue, or NULL if it was not possible to allocate the memory.

QueueValue queue_peek_head

(

Queue *

queue

)

Read value from the head of a queue, without removing it from the queue.

Parameters:

queue

The queue.

Returns:

Value at the head of the queue, or QUEUE_NULL if the queue is empty.

QueueValue queue_peek_tail

(

Queue *

queue

)

Read a value from the tail of a queue, without removing it from the queue.

Parameters:

queue

The queue.

Returns:

Value at the tail of the queue, or QUEUE_NULL if the queue is empty.

QueueValue queue_pop_head

(

Queue *

queue

)

Remove a value from the head of a queue.

Parameters:

queue

The queue.

Returns:

Value that was at the head of the queue, or QUEUE_NULL if the queue is empty.

QueueValue queue_pop_tail

(

Queue *

queue

)

Remove a value from the tail of a queue.

Parameters:

queue

The queue.

Returns:

Value that was at the head of the queue, or QUEUE_NULL if the queue is empty.

int queue_push_head	(	Queue *	queue,
		QueueValue	data
	)

Add a value to the head of a queue.

Parameters:

	queue	The queue.
	data	The value to add.

Returns:

Non-zero if the value was added successfully, or zero if it was not possible to allocate the memory for the new entry.

int queue_push_tail	(	Queue *	queue,
		QueueValue	data
	)

Add a value to the tail of a queue.

Parameters:

	queue	The queue.
	data	The value to add.

Returns:

Non-zero if the value was added successfully, or zero if it was not possible to allocate the memory for the new entry.