result_info_decl.h

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#ifndef A_UTIL_UTIL_RESULT_RESULT_INFO_DECL_HEADER_INCLUDED
#define A_UTIL_UTIL_RESULT_RESULT_INFO_DECL_HEADER_INCLUDED
 
#include <a_util/preprocessor/deprecated.h>
 
#include <cstdint>
#include <limits>

#ifndef DEV_ESSENTIAL_DISABLE_MAKE_RESULT_CHECK_RESERVED_ZERO
#define DEV_ESSENTIAL_INTERNAL_MAKE_RESULT_CHECK_NOT_ZERO(_no) _no != 0
#else
#define DEV_ESSENTIAL_INTERNAL_MAKE_RESULT_CHECK_NOT_ZERO(...) true
#endif // DEV_ESSENTIAL_DISABLE_MAKE_RESULT_CHECK_RESERVED_ZERO

#define _MAKE_RESULT(_no, _label)                                                                  \
    namespace {                                                                                    \
    struct ResultType_##_label : public ::a_util::result::ResultInfo<ResultType_##_label> {        \
        static std::int32_t getCode()                                                              \
        {                                                                                          \
            static_assert(std::is_same<decltype((_no)), std::int32_t>::value,                      \
                          #_no " is not in range of std::int32_t.");                               \
            return _no;                                                                            \
        }                                                                                          \
        static const char* getLabel()                                                              \
        {                                                                                          \
            return #_label;                                                                        \
        }                                                                                          \
    };                                                                                             \
    const ::a_util::result::ResultInfo<ResultType_##_label> _label = ResultType_##_label();        \
    } /* ns anonymous */                                                                           \
    static_assert(DEV_ESSENTIAL_INTERNAL_MAKE_RESULT_CHECK_NOT_ZERO(_no),                          \
                  "'0' is not allowed, because it is reserved for results indicating no error. "   \
                  "Please use a_util::result::SUCCESS instead. To disable this check, define "     \
                  "'DEV_ESSENTIAL_DISABLE_MAKE_RESULT_CHECK_RESERVED_ZERO'")
 
namespace a_util {
namespace result {
template <typename ResultType>
DEV_ESSENTIAL_DEPRECATED("Usage of this function template is not type safe.")
bool isOk(const ResultType& result);

template <typename ResultType>
DEV_ESSENTIAL_DEPRECATED("Usage of this function template is not type safe.")
bool isFailed(const ResultType& result);

template <typename T>
struct ResultInfo {
    static std::int32_t getCode();
    static const char* getLabel();
};

template <>
struct ResultInfo<void> {
    static std::int32_t getCode();
    static const char* getLabel();
};
 
namespace {
const ResultInfo<void> SUCCESS = ResultInfo<void>();
} // namespace

template <typename ResultTypeLHS, typename ResultTypeRHS>
bool operator==(const ResultInfo<ResultTypeLHS>& lhs, const ResultInfo<ResultTypeRHS>& rhs);

template <typename ResultTypeLHS, typename ResultTypeRHS>
bool operator!=(const ResultInfo<ResultTypeLHS>& lhs, const ResultInfo<ResultTypeRHS>& rhs);

template <typename ResultTypeLHS, typename ResultTypeRHS>
bool operator<(const ResultInfo<ResultTypeLHS>& lhs, const ResultInfo<ResultTypeRHS>& rhs);

template <typename ResultTypeLHS, typename ResultTypeRHS>
bool operator>(const ResultInfo<ResultTypeLHS>& lhs, const ResultInfo<ResultTypeRHS>& rhs);

template <typename ResultTypeLHS, typename ResultTypeRHS>
bool operator<=(const ResultInfo<ResultTypeLHS>& lhs, const ResultInfo<ResultTypeRHS>& rhs);

template <typename ResultTypeLHS, typename ResultTypeRHS>
bool operator>=(const ResultInfo<ResultTypeLHS>& lhs, const ResultInfo<ResultTypeRHS>& rhs);
 
} // namespace result
} // namespace a_util

#include <a_util/result/detail/result_info_impl.h>
#endif // A_UTIL_UTIL_RESULT_RESULT_INFO_DECL_HEADER_INCLUDED