/******************************************************************************
* Copyright (C) 2019 Kitsune Ral <kitsune-ral@users.sf.net>
*
* This 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 2.1 of the License, or (at your option) any later version.
*
* This 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#pragma once
#include "util.h"
#include <QtCore/QPointer>
namespace Quotient {
namespace _impl {
template <typename... ArgTs>
using decorated_slot_tt =
std::function<void(QMetaObject::Connection&, const ArgTs&...)>;
template <typename SenderT, typename SignalT, typename ContextT, typename... ArgTs>
inline QMetaObject::Connection
connectDecorated(SenderT* sender, SignalT signal, ContextT* context,
decorated_slot_tt<ArgTs...> decoratedSlot,
Qt::ConnectionType connType)
{
// See https://bugreports.qt.io/browse/QTBUG-60339
#if QT_VERSION < QT_VERSION_CHECK(5, 10, 0)
auto pc = std::make_shared<QMetaObject::Connection>();
#else
auto pc = std::make_unique<QMetaObject::Connection>();
#endif
auto& c = *pc; // Resolve a reference before pc is moved to lambda
// Perfect forwarding doesn't work through signal-slot connections -
// arguments are always copied (at best - COWed) to the context of
// the slot. Therefore the slot decorator receives const ArgTs&...
// rather than ArgTs&&...
// TODO: std::bind_front() instead of lambda.
c = QObject::connect(sender, signal, context,
[pc = std::move(pc),
decoratedSlot = std::move(decoratedSlot)](const ArgTs&... args) {
Q_ASSERT(*pc); // If it's been triggered, it should exist
decoratedSlot(*pc, args...);
},
connType);
return c;
}
template <typename SenderT, typename SignalT, typename ContextT,
typename... ArgTs>
inline QMetaObject::Connection
connectUntil(SenderT* sender, SignalT signal, ContextT* context,
std::function<bool(ArgTs...)> functor,
Qt::ConnectionType connType)
{
return connectDecorated(sender, signal, context,
decorated_slot_tt<ArgTs...>(
[functor = std::move(functor)](QMetaObject::Connection& c,
const ArgTs&... args) {
if (functor(args...))
QObject::disconnect(c);
}),
connType);
}
template <typename SenderT, typename SignalT, typename ContextT,
typename... ArgTs>
inline QMetaObject::Connection
connectSingleShot(SenderT* sender, SignalT signal, ContextT* context,
std::function<void(ArgTs...)> slot,
Qt::ConnectionType connType)
{
return connectDecorated(sender, signal, context,
decorated_slot_tt<ArgTs...>(
[slot = std::move(slot)](QMetaObject::Connection& c,
const ArgTs&... args) {
QObject::disconnect(c);
slot(args...);
}),
connType);
}
} // namespace _impl
/// Create a connection that self-disconnects when its "slot" returns true
/*! A slot accepted by connectUntil() is different from classic Qt slots
* in that its return value must be bool, not void. The slot's return value
* controls whether the connection should be kept; if the slot returns false,
* the connection remains; upon returning true, the slot is disconnected from
* the signal. Because of a different slot signature connectUntil() doesn't
* accept member functions as QObject::connect or Quotient::connectSingleShot
* do; you should pass a lambda or a pre-bound member function to it.
*/
template <typename SenderT, typename SignalT, typename ContextT, typename FunctorT>
inline auto connectUntil(SenderT* sender, SignalT signal, ContextT* context,
const FunctorT& slot,
Qt::ConnectionType connType = Qt::AutoConnection)
{
return _impl::connectUntil(sender, signal, context, wrap_in_function(slot),
connType);
}
/// Create a connection that self-disconnects after triggering on the signal
template <typename SenderT, typename SignalT, typename ContextT, typename FunctorT>
inline auto connectSingleShot(SenderT* sender, SignalT signal,
ContextT* context, const FunctorT& slot,
Qt::ConnectionType connType = Qt::AutoConnection)
{
return _impl::connectSingleShot(
sender, signal, context, wrap_in_function(slot), connType);
}
// Specialisation for usual Qt slots passed as pointers-to-members.
template <typename SenderT, typename SignalT, typename ReceiverT,
typename SlotObjectT, typename... ArgTs>
inline auto connectSingleShot(SenderT* sender, SignalT signal,
ReceiverT* receiver,
void (SlotObjectT::*slot)(ArgTs...),
Qt::ConnectionType connType = Qt::AutoConnection)
{
// TODO: when switching to C++20, use std::bind_front() instead
return _impl::connectSingleShot(sender, signal, receiver,
wrap_in_function(
[receiver, slot](const ArgTs&... args) {
(receiver->*slot)(args...);
}),
connType);
}
/// A guard pointer that disconnects an interested object upon destruction
/*! It's almost QPointer<> except that you have to initialise it with one
* more additional parameter - a pointer to a QObject that will be
* disconnected from signals of the underlying pointer upon the guard's
* destruction. Note that destructing the guide doesn't destruct either QObject.
*/
template <typename T>
class ConnectionsGuard : public QPointer<T> {
public:
ConnectionsGuard(T* publisher, QObject* subscriber)
: QPointer<T>(publisher), subscriber(subscriber)
{}
~ConnectionsGuard()
{
if (*this)
(*this)->disconnect(subscriber);
}
ConnectionsGuard(ConnectionsGuard&&) = default;
ConnectionsGuard& operator=(ConnectionsGuard&&) = default;
Q_DISABLE_COPY(ConnectionsGuard)
using QPointer<T>::operator=;
private:
QObject* subscriber;
};
} // namespace Quotient