Cache for pairs

cache.hpp

#pragma once

#include <deque>
#include <algorithm>

template<typename Key, typename Value>
class Cache{
    private:
        std::deque<std::pair<Key,Value>> data;
        const unsigned int max_size;
    public:
        Cache(unsigned int max_size = 64) : max_size(max_size){}
        bool contains(Key key){
            return std::find_if(this->data.begin(), this->data.end(), [&key](std::pair<Key,Value>& entry){
                return entry.first == key;
            }) != this->data.end();
        }
        Value get(Key key){
            auto it = std::find_if(this->data.begin(), this->data.end(), [&key](std::pair<Key,Value>& entry){
                return entry.first == key;
            });
            if(it != this->data.end()){
                auto elem = *it;
                this->data.erase(it);
                this->data.push_front(elem);
                return elem.second;
            }else
                return Value();
        }
        void add(Key key, Value value){
            this->data.push_front({key, value});
            if(this->data.size() > this->max_size)
                this->data.pop_back();
        }
        void clear(){
            this->data.clear();
        }
};