93 lines
2.2 KiB
C
93 lines
2.2 KiB
C
#pragma once
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/**
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* @brief An pair consisting of a priority and a pointer to be stored in
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* a priority queue.
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*
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*/
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struct priority_queue_node_t
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{
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/**
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* @brief A pointer to some user-defined object.
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*
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*/
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void *value;
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/**
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* @brief The priority of the associated object. Only the object with the
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* lowest priority is directly accessible from a priority queue.
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*
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*/
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int priority;
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};
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/**
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* @brief A priority queue. Each object in the queue contains a priority and
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* a pointer to some user-defined value, and a priority. Operations on the
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* queue consist of insertion and deletion of objects, and extraction of the
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* object with the lowest priority.
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*
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*/
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struct priority_queue_t
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{
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/**
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* @brief A pointer to the heap described by this structure.
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*
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*/
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struct priority_queue_node_t *heap;
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/**
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* @brief The current number of elements stored in the heap.
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*
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*/
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int size;
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/**
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* @brief The maximum number of elements that the heap can currently hold.
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*
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*/
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int capacity;
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};
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/**
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* @brief Initializes the given queue struct.
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*
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* The queue's underlying heap is allocated
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*
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* @param queue
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* @return int
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*/
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int construct_priority_queue(struct priority_queue_t *queue, int capacity);
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/**
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* @brief Extracts the object with the lowest priority off the given queue.
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*
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* The object is removed from the queue, and a pointer to its userdata is
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* returned. If the queue is empty, this function returns NULL and the queue
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* is unaffected. If multiple objects with the same priority are stored on the
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* queue, this function will extract the object lest-recently inserted.
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*
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* @param queue
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* @return void*
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*/
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void *priorityqueue_extract_min(struct priority_queue_t *queue);
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/**
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* @brief Inserts a new object onto the queue.
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*
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* @param queue
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* @param value
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* @param priority
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* @return int
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*/
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int priorityqueue_insert(struct priority_queue_t *queue, void *value, int priority);
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/**
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* @brief Removes the object with a matching value from the queue.
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*
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* @param queue
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* @param value
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* @return int
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*/
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int priorityqueue_remove(struct priority_queue_t *queue, void *value);
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