ClickHouse/base/common/scope_guard.h
2021-06-16 23:28:41 +03:00

111 lines
2.9 KiB
C++

#pragma once
#include <functional>
#include <memory>
#include <utility>
template <class F>
class [[nodiscard]] basic_scope_guard
{
public:
constexpr basic_scope_guard() = default;
constexpr basic_scope_guard(basic_scope_guard && src) : function{src.release()} {}
constexpr basic_scope_guard & operator=(basic_scope_guard && src)
{
if (this != &src)
{
invoke();
function = src.release();
}
return *this;
}
template <typename G, typename = std::enable_if_t<std::is_convertible_v<G, F>, void>>
constexpr basic_scope_guard(basic_scope_guard<G> && src) : function{src.release()} {}
template <typename G, typename = std::enable_if_t<std::is_convertible_v<G, F>, void>>
constexpr basic_scope_guard & operator=(basic_scope_guard<G> && src)
{
if (this != &src)
{
invoke();
function = src.release();
}
return *this;
}
template <typename G, typename = std::enable_if_t<std::is_convertible_v<G, F>, void>>
constexpr basic_scope_guard(const G & function_) : function{function_} {}
template <typename G, typename = std::enable_if_t<std::is_convertible_v<G, F>, void>>
constexpr basic_scope_guard(G && function_) : function{std::move(function_)} {}
~basic_scope_guard() { invoke(); }
static constexpr bool is_nullable = std::is_constructible_v<bool, F>;
explicit operator bool() const
{
if constexpr (is_nullable)
return static_cast<bool>(function);
return true;
}
void reset()
{
invoke();
release();
}
F release()
{
static_assert(is_nullable);
return std::exchange(function, {});
}
template <typename G, typename = std::enable_if_t<std::is_convertible_v<G, F>, void>>
basic_scope_guard<F> & join(basic_scope_guard<G> && other)
{
if (other.function)
{
if (function)
{
function = [x = std::make_shared<std::pair<F, G>>(std::move(function), other.release())]()
{
std::move(x->first)();
std::move(x->second)();
};
}
else
function = other.release();
}
return *this;
}
private:
void invoke()
{
if constexpr (is_nullable)
{
if (!function)
return;
}
std::move(function)();
}
F function = F{};
};
using scope_guard = basic_scope_guard<std::function<void(void)>>;
template <class F>
inline basic_scope_guard<F> make_scope_guard(F && function_) { return std::forward<F>(function_); }
#define SCOPE_EXIT_CONCAT(n, ...) \
const auto scope_exit##n = make_scope_guard([&] { __VA_ARGS__; })
#define SCOPE_EXIT_FWD(n, ...) SCOPE_EXIT_CONCAT(n, __VA_ARGS__)
#define SCOPE_EXIT(...) SCOPE_EXIT_FWD(__LINE__, __VA_ARGS__)