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#pragma once
#include <functional>
#include <memory>
#include <vector>
/**
* A class to be used to make sure some functions are called when the scope
* is left, because they will be called in the ScopeGuard's destructor. It
* can for example be used to delete some pointer whenever any exception is
* called. Example:
* {
* ScopeGuard scope;
* int* number = new int(2);
* scope.add_callback([number]() { delete number; });
* // Do some other stuff with the number. But these stuff might throw an exception:
* throw std::runtime_error("Some error not caught here, but in our caller");
* return true;
* }
* In this example, our pointer will always be deleted, even when the
* exception is thrown. If we want the functions to be called only when the
* scope is left because of an unexpected exception, we can use
* ScopeGuard::disable();
*/
namespace utils
{
class ScopeGuard
{
public:
/**
* The constructor can take a callback. But additional callbacks can be
* added later with add_callback()
*/
explicit ScopeGuard(std::function<void()>&& func):
enabled(true)
{
this->add_callback(std::move(func));
}
ScopeGuard(const ScopeGuard&) = delete;
ScopeGuard& operator=(ScopeGuard&&) = delete;
ScopeGuard(ScopeGuard&&) = delete;
ScopeGuard& operator=(const ScopeGuard&) = delete;
/**
* default constructor, the scope guard is enabled but empty, use
* add_callback()
*/
explicit ScopeGuard():
enabled(true)
{
}
/**
* Call all callbacks in the desctructor, unless it has been disabled.
*/
~ScopeGuard()
{
if (this->enabled)
for (auto& func: this->callbacks)
func();
}
/**
* Add a callback to be called in our destructor, one scope guard can be
* used for more than one task, if needed.
*/
void add_callback(std::function<void()>&& func)
{
this->callbacks.emplace_back(std::move(func));
}
/**
* Disable that scope guard, nothing will be done when the scope is
* exited.
*/
void disable()
{
this->enabled = false;
}
private:
bool enabled;
std::vector<std::function<void()>> callbacks;
};
template<typename F>
auto make_scope_guard(F&& f)
{
return std::unique_ptr<void, std::decay_t<F>>{(void*)1, std::forward<F>(f)};
}
}
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