priority_queue.h
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/*
* Copyright (C) 2013, 2014 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @addtogroup core_util
* @{
*
* @file
* @brief A simple priority queue
*
* @author Kaspar Schleiser <kaspar@schleiser.de>
*/
#ifndef PRIORITY_QUEUE_H
#define PRIORITY_QUEUE_H
#include <stddef.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief data type for priority queue nodes
*/
typedef struct priority_queue_node {
struct priority_queue_node *next; /**< next queue node */
uint32_t priority; /**< queue node priority */
unsigned int data; /**< queue node data */
} priority_queue_node_t;
/**
* @brief data type for priority queues
*/
typedef struct {
priority_queue_node_t *first; /**< first queue node */
} priority_queue_t;
/**
* @brief Static initializer for priority_queue_node_t.
*/
#define PRIORITY_QUEUE_NODE_INIT { NULL, 0, 0 }
/**
* @brief Initialize a priority queue node object.
* @details For initialization of variables use PRIORITY_QUEUE_NODE_INIT
* instead. Only use this function for dynamically allocated
* priority queue nodes.
* @param[out] priority_queue_node
* pre-allocated priority_queue_node_t object, must not be NULL.
*/
static inline void priority_queue_node_init(
priority_queue_node_t *priority_queue_node)
{
priority_queue_node_t qn = PRIORITY_QUEUE_NODE_INIT;
*priority_queue_node = qn;
}
/**
* @brief Static initializer for priority_queue_t.
*/
#define PRIORITY_QUEUE_INIT { NULL }
/**
* @brief Initialize a priority queue object.
* @details For initialization of variables use PRIORITY_QUEUE_INIT
* instead. Only use this function for dynamically allocated
* priority queues.
* @param[out] priority_queue
* pre-allocated priority_queue_t object, must not be NULL.
*/
static inline void priority_queue_init(priority_queue_t *priority_queue)
{
priority_queue_t q = PRIORITY_QUEUE_INIT;
*priority_queue = q;
}
/**
* @brief remove the priority queue's head
*
* @param[out] root the queue's root
*
* @return the old head
*/
priority_queue_node_t *priority_queue_remove_head(priority_queue_t *root);
/**
* @brief insert `new_obj` into `root` based on its priority
*
* @details
* The new object will be appended after objects with the same priority.
*
* @param[in,out] root the queue's root
* @param[in] new_obj the object to prepend
*
* @pre The queue does not already contain @p new_obj.
*/
void priority_queue_add(priority_queue_t *root, priority_queue_node_t *new_obj);
/**
* @brief remove `node` from `root`
*
* @param[in,out] root the priority queue's root
* @param[in] node the node to remove
*/
void priority_queue_remove(priority_queue_t *root, priority_queue_node_t *node);
#if ENABLE_DEBUG
/**
* @brief print the data and priority of every node in the given priority queue
*
* @note requires ::ENABLE_DEBUG to be set to 1 for this file
*/
void priority_queue_print(priority_queue_t *root);
/**
* @brief print the data, priority, and successor of a given node
*
* @note requires ::ENABLE_DEBUG to be set to 1 for this file
*/
void priority_queue_print_node(priority_queue_t *root);
#endif
#ifdef __cplusplus
}
#endif
/** @} */
#endif /* PRIORITY_QUEUE_H */