#include <string>

namespace experimental
{
    // Peter's constexpr enhanced error category
    class error_category
    {
    public:
        constexpr error_category() = default;
        virtual std::string message(int c) const = 0;
        
        // NEW: True if the code is considered a failure
        virtual bool failure(int code) const noexcept
        {
            // Defaults to comparing to 0 for backwards compatibility with existing code
            return 0 != code;
        }
    };
    // Peter's constexpr enhanced error code
    class error_code
    {
        int _value;
        const error_category *_category;
    public:
        constexpr error_code(int v, const error_category &cat) : _value(v), _category(&cat) {}
        constexpr int value() const noexcept { return _value; }
        constexpr const error_category &category() const noexcept { return *_category; }
        std::string message() const { return _category->message(_value); }
        
        // Fixed operator bool, now asks category
        explicit operator bool() const noexcept
        {
          return _category->failure(_value);
        }
    };
} 

namespace experimental2
{
    class error_code
    {
        int _value;
        bool _is_failure;
        const experimental::error_category *_category;
    public:
        constexpr error_code(int v, const experimental::error_category &cat) : _value(v), _is_failure(v != 0), _category(&cat) {}
        constexpr error_code(int v, bool is_failure, const experimental::error_category &cat) : _value(v), _is_failure(is_failure), _category(&cat) {}
        constexpr int value() const noexcept { return _value; }
        constexpr const experimental::error_category &category() const noexcept { return *_category; }
        std::string message() const { return _category->message(_value); }
        
        // Fixed operator bool, now asks category
        explicit operator bool() const noexcept
        {
          return _is_failure;
        }
    };
}

// Test error code scheme where 0 is a failure, non-zero a success
enum class code
{
    failure=0,
    success=1
};

extern const experimental::error_category& code_category;