telodendria/Cytoplasm/src/include/Queue.h

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/*
* Copyright (C) 2022-2023 Jordan Bancino <@jordan:bancino.net>
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#ifndef CYTOPLASM_QUEUE_H
#define CYTOPLASM_QUEUE_H
/***
* @Nm Queue
* @Nd A simple static queue data structure.
* @Dd November 25 2022
* @Xr Array HashMap
*
* .Nm
* implements a simple queue data structure that is statically sized.
* This implementation does not actually store the values of the items
* in it; it only stores pointers to the data. As such, you will have
* to manually maintain data and make sure it remains valid as long as
* it is in the queue. The advantage of this is that
* .Nm
* doesn't have to copy data, and thus doesn't care how big the data
* is. Furthermore, any arbitrary data can be stored in the queue.
* .Pp
* This queue implementation operates on the heap. It is a circular
* queue, and it does not grow as it is used. Once the size is set,
* the queue never gets any bigger.
*/
#include <stddef.h>
/**
* These functions operate on a queue structure that is opaque to the
* caller.
*/
typedef struct Queue Queue;
/**
* Allocate a new queue that is able to store the specified number of
* items in it.
*/
extern Queue * QueueCreate(size_t);
/**
* Free the memory associated with the specified queue structure. Note
* that this function does not free any of the values stored in the
* queue; it is the caller's job to manage memory for each item.
* Typically, the caller would dequeue all the items in the queue and
* deal with them before freeing the queue itself.
*/
extern void QueueFree(Queue *);
/**
* Push an element into the queue. This function returns a boolean
* value indicating whether or not the push succeeded. Pushing items
* into the queue will fail if the queue is full.
*/
extern int QueuePush(Queue *, void *);
/**
* Pop an element out of the queue. This function returns NULL if the
* queue is empty. Otherwise, it returns a pointer to the item that is
* next up in the queue.
*/
extern void * QueuePop(Queue *);
/**
* Retrieve a pointer to the item that is next up in the queue without
* actually discarding it, such that the next call to
* .Fn QueuePeek
* or
* .Fn QueuePop
* will return the same pointer.
*/
extern void * QueuePeek(Queue *);
/**
* Determine whether or not the queue is full.
*/
extern int QueueFull(Queue *);
/**
* Determine whether or not the queue is empty.
*/
extern int QueueEmpty(Queue *);
#endif