1
0
mirror of https://github.com/danog/ton.git synced 2024-12-12 17:17:22 +01:00
ton/tdutils/td/utils/as.h
2019-09-07 14:33:36 +04:00

99 lines
2.4 KiB
C++

/*
This file is part of TON Blockchain Library.
TON Blockchain Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
TON Blockchain Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with TON Blockchain Library. If not, see <http://www.gnu.org/licenses/>.
Copyright 2017-2019 Telegram Systems LLP
*/
#pragma once
#include <cstring>
#include <type_traits>
namespace td {
namespace detail {
template <class T>
class As {
public:
explicit As(void *ptr) : ptr_(ptr) {
}
As(const As &new_value) = delete;
As &operator=(const As &) = delete;
As(As &&) = default;
As &operator=(As &&new_value) && {
std::memcpy(ptr_, new_value.ptr_, sizeof(T));
return *this;
}
~As() = default;
As &operator=(T new_value) && {
std::memcpy(ptr_, &new_value, sizeof(T));
return *this;
}
operator T() const {
T res;
std::memcpy(&res, ptr_, sizeof(T));
return res;
}
bool operator==(const As &other) const {
return this->operator T() == other.operator T();
}
private:
void *ptr_;
};
template <class T>
class ConstAs {
public:
explicit ConstAs(const void *ptr) : ptr_(ptr) {
}
operator T() const {
T res;
std::memcpy(&res, ptr_, sizeof(T));
return res;
}
private:
const void *ptr_;
};
} // namespace detail
// no std::is_trivially_copyable in libstdc++ before 5.0
#if __GLIBCXX__
#define TD_IS_TRIVIALLY_COPYABLE(T) __has_trivial_copy(T)
#else
#define TD_IS_TRIVIALLY_COPYABLE(T) std::is_trivially_copyable<T>::value
#endif
template <class ToT, class FromT,
std::enable_if_t<TD_IS_TRIVIALLY_COPYABLE(ToT) && TD_IS_TRIVIALLY_COPYABLE(FromT), int> = 0>
detail::As<ToT> as(FromT *from) {
return detail::As<ToT>(from);
}
template <class ToT, class FromT,
std::enable_if_t<TD_IS_TRIVIALLY_COPYABLE(ToT) && TD_IS_TRIVIALLY_COPYABLE(FromT), int> = 0>
const detail::ConstAs<ToT> as(const FromT *from) {
return detail::ConstAs<ToT>(from);
}
} // namespace td