tdesktop/Telegram/SourceFiles/base/lambda_guard.h

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/*
This file is part of Telegram Desktop,
the official desktop application for the Telegram messaging service.
For license and copyright information please follow this link:
https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
*/
#pragma once
#include <QPointer>
#include "base/weak_ptr.h"
// Guard lambda call by QObject* or has_weak_ptr* 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::has_weak_ptr *object,
OtherLambda &&other)
: _guard(base::make_weak(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)...)
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: 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)...)
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: Return();
}
private:
base::weak_ptr<const base::has_weak_ptr> _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::has_weak_ptr *object,
Lambda &&lambda) {
using Guarded = lambda_internal::guard_with_weak<
std::decay_t<Lambda>>;
return Guarded(object, std::forward<Lambda>(lambda));
}
} // namespace base