peony / src / queue.hpp

// (c) 2020 Vlad-Stefan Harbuz <[e-mail]>

#pragma once

#include "memory.hpp"

template <typename T>
class Queue {
public:
    u32 size = 0;
    u32 max_size = 0;
    T *items = nullptr;
    u32 head = 0;
    u32 tail = 0;

    T* push() {
        assert(this->size < this->max_size);
        T* new_slot = this->items + this->tail;
        if (this->tail + 1 >= this->max_size) {
            this->tail = 0;
        } else {
            this->tail++;
        }
        this->size++;
        return new_slot;
    }

    T push(T new_item) {
        T* new_slot = push();
        *new_slot = new_item;
        return new_item;
    }

    T* pop() {
        assert(this->size > 0);
        T* item = this->items + this->head;
        if (this->head + 1 >= this->max_size) {
            this->head = 0;
        } else {
            this->head++;
        }
        this->size--;
        return item;
    }

    Queue(memory::Pool *memory_pool, u32 new_max_size, const char *debug_name) {
        this->max_size = new_max_size;
        this->items = (T*)memory::push(memory_pool, sizeof(T) * this->max_size, debug_name);
    }

    Queue(memory::Pool *memory_pool, u32 new_size, u32 new_max_size, T *new_items) {
        this->size = new_size;
        this->head = 0;
        this->tail = new_size;
        this->max_size = new_max_size;
        this->items = new_items;
    }
};