FixedSizeQueue.h

#pragma once
 
#include <deque>
 
template <typename T>
class FixedSizeQueue {
public:
    explicit FixedSizeQueue(size_t capacity = 1ul) : _capacity{capacity} {};
 
    void setCapacity(size_t new_capacity){
        _capacity = new_capacity;
        // shrink to fit:
        while(_storage.size() > _capacity){
            _storage.pop_front();
        }
    }
 
    void insert(const T& t) {
        if (_storage.size() == _capacity) {
            _storage.push_back(t);
            _storage.pop_front();
        } else {
            _storage.push_back(t);
        }
    }
 
    auto begin() { return _storage.begin(); }
 
    auto begin() const { return _storage.cbegin(); }
 
    auto end() { return _storage.end(); }
 
    auto end() const { return _storage.cend(); }
 
    [[nodiscard]] size_t size() const {
        return _storage.size();
    }
private:
    size_t _capacity{0ul};
 
    std::deque<T> _storage;
};