messageException.h

#pragma once
 
#include <optional>
#include <exception>
 
namespace TuringSim::Utils {
    class MessageException : public std::exception {
    public:
        MessageException() = delete;
 
        MessageException(std::string message) noexcept : msg(message) {}
 
        MessageException(const MessageException& e) = default;
 
        MessageException(MessageException&& e) = default;
 
        ~MessageException() noexcept override = default;
 
        std::string getMessage() const {
            ensureFullMessage();
            return *fullMsg;
        }
 
        const char* what() const noexcept override {
            ensureFullMessage();
            return fullMsg->c_str();
        }
 
        explicit operator std::string() const {
            ensureFullMessage();
            return getMessage();
        }
 
    private:
        void ensureFullMessage() const {
            if(!fullMsg) {
                fullMsg = this->makeFullMessage();
            }
        }
 
    protected:
        virtual std::string makeFullMessage() const {
            return msg;
        }
 
        std::string msg;  
        mutable std::optional<std::string> fullMsg;  
    };
 
    template<typename CharT, typename Traits>
    std::basic_ostream<CharT, Traits>& operator<<(std::basic_ostream<CharT, Traits>& os, const MessageException& e) {
        return os << e.getMessage();
    }
 
}