libcruft-util/typeidx.hpp

47 lines
1.5 KiB
C++

/*
* 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.
*
* Copyright 2017 Danny Robson <danny@nerdcruft.net>
*/
#ifndef CRUFT_UTIL_TYPEIDX_HPP
#define CRUFT_UTIL_TYPEIDX_HPP
#include <cstdint>
namespace util {
namespace detail { std::uintptr_t typeidx_next (void); }
/// return a globally unique runtime ID for a given type.
///
/// this is intended to be used as a lightweight type check for variants
/// and such without requiring RTTI.
///
/// the identifier is constructed at runtime and is not guaranteed to be
/// stable across executions (particularly in the case of threads and
/// other non-determinism).
///
/// the range of identifiers is _probably_ contiguous starting from zero.
/// this should not be relied upon for correctness, but may be used for
/// performance concerns.
template <typename T>
std::uintptr_t
typeidx (void)
{
static auto id = detail::typeidx_next ();
return id;
}
}
#endif