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/*
* Copyright (C) the libgit2 contributors. All rights reserved.
*
* This file is part of libgit2, distributed under the GNU GPL v2 with
* a Linking Exception. For full terms see the included COPYING file.
*
* This file is based on a modified version of the priority queue found
* in the Apache project and libpqueue library.
*
* https://github.com/vy/libpqueue
*
* Original file notice:
*
* Copyright 2010 Volkan Yazici <volkan.yazici@gmail.com>
* Copyright 2006-2010 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
#ifndef INCLUDE_pqueue_h__
#define INCLUDE_pqueue_h__
/** callback functions to get/set/compare the priority of an element */
typedef int (*git_pqueue_cmp)(void *a, void *b);
/** the priority queue handle */
typedef struct {
size_t size, avail, step;
git_pqueue_cmp cmppri;
void **d;
} git_pqueue;
/**
* 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 compare two nodes of the queue
*
* @Return the handle or NULL for insufficent memory
*/
int git_pqueue_init(git_pqueue *q, size_t n, git_pqueue_cmp cmppri);
/**
* free all memory used by the queue
* @param q the queue
*/
void git_pqueue_free(git_pqueue *q);
/**
* clear all the elements in the queue
* @param q the queue
*/
void git_pqueue_clear(git_pqueue *q);
/**
* return the size of the queue.
* @param q the queue
*/
size_t git_pqueue_size(git_pqueue *q);
/**
* insert an item into the queue.
* @param q the queue
* @param d the item
* @return 0 on success
*/
int git_pqueue_insert(git_pqueue *q, void *d);
/**
* pop the highest-ranking item from the queue.
* @param p the queue
* @param d where to copy the entry to
* @return NULL on error, otherwise the entry
*/
void *git_pqueue_pop(git_pqueue *q);
/**
* access highest-ranking item without removing it.
* @param q the queue
* @param d the entry
* @return NULL on error, otherwise the entry
*/
void *git_pqueue_peek(git_pqueue *q);
#endif /* PQUEUE_H */
/** @} */
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