darling-WTF/wtf/EnumTraits.h
2018-01-05 13:44:16 -08:00

65 lines
2.3 KiB
C++

/*
* Copyright (C) 2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <type_traits>
namespace WTF {
template<typename> struct EnumTraits;
template<typename E, E...> struct EnumValues;
template<typename T, typename E> struct EnumValueChecker;
template<typename T, typename E, E e, E... es>
struct EnumValueChecker<T, EnumValues<E, e, es...>> {
static constexpr bool isValidEnum(T t)
{
return (static_cast<T>(e) == t) ? true : EnumValueChecker<T, EnumValues<E, es...>>::isValidEnum(t);
}
};
template<typename T, typename E>
struct EnumValueChecker<T, EnumValues<E>> {
static constexpr bool isValidEnum(T)
{
return false;
}
};
template<typename E, typename T>
constexpr auto isValidEnum(T t) -> std::enable_if_t<std::is_enum<E>::value, bool>
{
static_assert(sizeof(T) >= std::underlying_type_t<E>(), "Integral type must be at least the size of the underlying enum type");
return EnumValueChecker<T, typename EnumTraits<E>::values>::isValidEnum(t);
}
}
using WTF::isValidEnum;