tdesktop/Telegram/SourceFiles/base/lambda_guard.h

128 lines
3.4 KiB
C++

/*
This file is part of Telegram Desktop,
the official desktop version of Telegram messaging app, see https://telegram.org
Telegram Desktop is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
It 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 General Public License for more details.
In addition, as a special exception, the copyright holders give permission
to link the code of portions of this program with the OpenSSL library.
Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
*/
#pragma once
#include <QPointer>
#include "base/weak_unique_ptr.h"
// Guard lambda call by QObject* or enable_weak_from_this* pointers.
namespace base {
namespace lambda_internal {
template <typename Lambda>
class guard_with_QObject {
public:
template <typename OtherLambda>
guard_with_QObject(const QObject *object, OtherLambda &&other)
: _guard(object)
, _callable(std::forward<OtherLambda>(other)) {
}
template <
typename ...OtherArgs,
typename Return = decltype(std::declval<Lambda>()(std::declval<OtherArgs>()...))>
Return operator()(OtherArgs &&...args) {
return _guard
? _callable(std::forward<OtherArgs>(args)...)
: Return();
}
template <
typename ...OtherArgs,
typename Return = decltype(std::declval<Lambda>()(std::declval<OtherArgs>()...))>
Return operator()(OtherArgs &&...args) const {
return _guard
? _callable(std::forward<OtherArgs>(args)...)
: Return();
}
private:
QPointer<const QObject> _guard;
Lambda _callable;
};
template <typename Lambda>
class guard_with_weak {
public:
template <typename OtherLambda>
guard_with_weak(
const base::enable_weak_from_this *object,
OtherLambda &&other)
: _guard(base::make_weak_unique(object))
, _callable(std::forward<OtherLambda>(other)) {
}
template <
typename ...OtherArgs,
typename Return = decltype(std::declval<Lambda>()(std::declval<OtherArgs>()...))>
Return operator()(OtherArgs &&...args) {
return _guard
? _callable(std::forward<OtherArgs>(args)...)
: Return{};
}
template <
typename ...OtherArgs,
typename Return = decltype(std::declval<Lambda>()(std::declval<OtherArgs>()...))>
Return operator()(OtherArgs &&...args) const {
return _guard
? _callable(std::forward<OtherArgs>(args)...)
: Return{};
}
private:
base::weak_unique_ptr<const base::enable_weak_from_this> _guard;
Lambda _callable;
};
template <typename Lambda>
struct lambda_call_type<guard_with_QObject<Lambda>> {
using type = lambda_call_type_t<Lambda>;
};
template <typename Lambda>
struct lambda_call_type<guard_with_weak<Lambda>> {
using type = lambda_call_type_t<Lambda>;
};
} // namespace lambda_internal
template <typename Lambda>
inline auto lambda_guarded(const QObject *object, Lambda &&lambda) {
using Guarded = lambda_internal::guard_with_QObject<
std::decay_t<Lambda>>;
return Guarded(object, std::forward<Lambda>(lambda));
}
template <typename Lambda>
inline auto lambda_guarded(
const base::enable_weak_from_this *object,
Lambda &&lambda) {
using Guarded = lambda_internal::guard_with_weak<
std::decay_t<Lambda>>;
return Guarded(object, std::forward<Lambda>(lambda));
}
} // namespace base