priority_queue.h

#ifndef PRIORITY_QUEUE_H
#define PRIORITY_QUEUE_H
#include <iostream>

template <typename T>
class Priority_queue {
    T* data = nullptr;
    size_t _size = 0; // the number of elements
    size_t _capacity = 0; // the number of elements that can be held in currently allocated storage

    void resize(void);
    void bottom_up_heapify(void);
    void top_down_heapify(void);
    size_t bigger_family_member(size_t parent_index);
public:
    Priority_queue() = default;
    ~Priority_queue();

    size_t size(void);
    size_t capacity(void);
    bool empty(void);
    void clear(void);

    void push(const T& elem);
    T top(void);
    T pop(void);

    template <typename U>
    friend std::ostream& operator<<(std::ostream& out, const Priority_queue<U>& v);

#ifdef TESTING
protected:
    friend void test_bottom_up_heapify(void);
    friend void test_top_down_heapify(void);
    friend void test_bigger_family_member_method(void);
#endif // TESTING
};

#endif // PRIORITY_QUEUE_H