rtti_utils.h

/*
 * SPDX-FileCopyrightText: 2024 Intel Corporation.
 * Copyright 2024-present Intel Corporation.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

 
#ifndef LIB_RTTI_UTILS_H_
#define LIB_RTTI_UTILS_H_
 
#include <type_traits>
 
#include "rtti.h"
 
namespace P4::RTTI {

template <typename T>
struct has_rtti : std::is_base_of<RTTI::Base, T> {};

template <typename T>
inline constexpr const bool has_rtti_v = has_rtti<T>::value;

template <typename... Ts>
inline constexpr const bool all_have_rtti_v = (has_rtti_v<Ts> && ...);

template <typename T, typename R = void>
struct enable_if_has_rtti : std::enable_if<has_rtti_v<T>, R> {};

template <typename... Ts>
using enable_if_all_have_rtti_t = std::enable_if_t<all_have_rtti_v<Ts...>, void>;

template <typename T, typename R = void>
using enable_if_has_rtti_t = typename enable_if_has_rtti<T, R>::type;
 
namespace Detail {
 
template <typename To, typename = enable_if_has_rtti_t<To>>
struct ToType {
    template <typename From, typename = enable_if_has_rtti_t<From>>
    To *operator()(From *obj) const {
        return obj ? obj->template to<To>() : nullptr;
    }
 
    template <typename From, typename = enable_if_has_rtti_t<From>>
    const To *operator()(const From *obj) const {
        return obj ? obj->template to<To>() : nullptr;
    }
};
 
template <typename... Targets>
// TODO(C++20): use concepts to check enable_if_all_have_rtti_t<Targets...>> & that there is at
// least 1 target type.
struct IsType {
    static_assert(sizeof...(Targets) > 0,
                  "At least one target type needs to be given for RTTI::is");
    static_assert(all_have_rtti_v<Targets...>,
                  "All types in RTTI::is<Ts> need to be custom-rtti-enabled");
 
    template <typename From, typename = enable_if_has_rtti_t<From>>
    bool operator()(const From *obj) const {
        return obj && (obj->template is<Targets>() || ...);
    }
};
 
}  // namespace Detail

template <typename To>
inline const Detail::ToType<To> to;

template <typename Target>
inline const Detail::IsType<Target> is;

template <typename... Targets>
inline const Detail::IsType<Targets...> isAny;
 
}  // namespace P4::RTTI
 
#endif  // LIB_RTTI_UTILS_H_