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// Copyright 2020 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef COMMON_UNDERLYINGTYPE_H_
#define COMMON_UNDERLYINGTYPE_H_
#include <type_traits>
// UnderlyingType is similar to std::underlying_type_t. It is a passthrough for already
// integer types which simplifies getting the underlying primitive type for an arbitrary
// template parameter. It includes a specialization for detail::TypedIntegerImpl which yields
// the wrapped integer type.
namespace detail {
template <typename T, typename Enable = void>
struct UnderlyingTypeImpl;
template <typename I>
struct UnderlyingTypeImpl<I, typename std::enable_if_t<std::is_integral<I>::value>> {
using type = I;
};
template <typename E>
struct UnderlyingTypeImpl<E, typename std::enable_if_t<std::is_enum<E>::value>> {
using type = std::underlying_type_t<E>;
};
// Forward declare the TypedInteger impl.
template <typename Tag, typename T>
class TypedIntegerImpl;
template <typename Tag, typename I>
struct UnderlyingTypeImpl<TypedIntegerImpl<Tag, I>> {
using type = typename UnderlyingTypeImpl<I>::type;
};
} // namespace detail
template <typename T>
using UnderlyingType = typename detail::UnderlyingTypeImpl<T>::type;
#endif // COMMON_UNDERLYINGTYPE_H_