pqueue.h

/*
 * Copyright (c) 2014, Volkan Yazıcı <volkan.yazici@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


/**
 * @file  pqueue.h
 * @brief Priority Queue function declarations
 *
 * @{
 */


#ifndef PQUEUE_H
#define PQUEUE_H

/** priority data type */
typedef unsigned long long pqueue_pri_t;

/** callback functions to get/set/compare the priority of an element */
typedef pqueue_pri_t (*pqueue_get_pri_f)(void *a);
typedef void (*pqueue_set_pri_f)(void *a, pqueue_pri_t pri);
typedef int (*pqueue_cmp_pri_f)(pqueue_pri_t next, pqueue_pri_t curr);


/** callback functions to get/set the position of an element */
typedef size_t (*pqueue_get_pos_f)(void *a);
typedef void (*pqueue_set_pos_f)(void *a, size_t pos);


/** debug callback function to print a entry */
typedef void (*pqueue_print_entry_f)(FILE *out, void *a);


/** the priority queue handle */
typedef struct pqueue_t
{
    size_t size;                /**< number of elements in this queue */
    size_t avail;               /**< slots available in this queue */
    size_t step;                /**< growth stepping setting */
    pqueue_cmp_pri_f cmppri;    /**< callback to compare nodes */
    pqueue_get_pri_f getpri;    /**< callback to get priority of a node */
    pqueue_set_pri_f setpri;    /**< callback to set priority of a node */
    pqueue_get_pos_f getpos;    /**< callback to get position of a node */
    pqueue_set_pos_f setpos;    /**< callback to set position of a node */
    void **d;                   /**< The actualy queue in binary heap form */
} pqueue_t;


/**
 * initialize the queue
 *
 * @param n the initial estimate of the number of queue items for which memory
 *     should be preallocated
 * @param cmppri The callback function to run to compare two elements
 *     This callback should return 0 for 'lower' and non-zero
 *     for 'higher', or vice versa if reverse priority is desired
 * @param setpri the callback function to run to assign a score to an element
 * @param getpri the callback function to run to set a score to an element
 * @param getpos the callback function to get the current element's position
 * @param setpos the callback function to set the current element's position
 *
 * @return the handle or NULL for insufficent memory
 */
pqueue_t *
pqueue_init(size_t n,
            pqueue_cmp_pri_f cmppri,
            pqueue_get_pri_f getpri,
            pqueue_set_pri_f setpri,
            pqueue_get_pos_f getpos,
            pqueue_set_pos_f setpos);


/**
 * free all memory used by the queue
 * @param q the queue
 */
void pqueue_free(pqueue_t *q);


/**
 * return the size of the queue.
 * @param q the queue
 */
size_t pqueue_size(pqueue_t *q);


/**
 * insert an item into the queue.
 * @param q the queue
 * @param d the item
 * @return 0 on success
 */
int pqueue_insert(pqueue_t *q, void *d);


/**
 * move an existing entry to a different priority
 * @param q the queue
 * @param new_pri the new priority
 * @param d the entry
 */
void
pqueue_change_priority(pqueue_t *q,
                       pqueue_pri_t new_pri,
                       void *d);


/**
 * pop the highest-ranking item from the queue.
 * @param q the queue
 * @return NULL on error, otherwise the entry
 */
void *pqueue_pop(pqueue_t *q);


/**
 * remove an item from the queue.
 * @param q the queue
 * @param d the entry
 * @return 0 on success
 */
int pqueue_remove(pqueue_t *q, void *d);


/**
 * access highest-ranking item without removing it.
 * @param q the queue
 * @return NULL on error, otherwise the entry
 */
void *pqueue_peek(pqueue_t *q);


/**
 * print the queue
 * @internal
 * DEBUG function only
 * @param q the queue
 * @param out the output handle
 * @param the callback function to print the entry
 */
void
pqueue_print(pqueue_t *q, 
             FILE *out,
             pqueue_print_entry_f print);


/**
 * dump the queue and it's internal structure
 * @internal
 * debug function only
 * @param q the queue
 * @param out the output handle
 * @param the callback function to print the entry
 */
void
pqueue_dump(pqueue_t *q, 
             FILE *out,
             pqueue_print_entry_f print);


/**
 * checks that the pq is in the right order, etc
 * @internal
 * debug function only
 * @param q the queue
 */
int pqueue_is_valid(pqueue_t *q);


#endif /* PQUEUE_H */
/** @} */