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#pragma once
#include "ndebug-guard.hpp"
#include <cassert>
#include <thread>
#include <condition_variable>
#include <utility>
#include <QObject>
#include <QThread>
namespace qt_impl_detail {
template<typename t>
struct run_in_thread_traits
{
using type = t;
using ret_type = t;
static inline void assign(t& lvalue, const t& rvalue) { lvalue = rvalue; }
static inline t pass(const t& val) { return val; }
template<typename F> static inline t call(F&& fun) { return std::move(fun()); }
};
template<typename u>
struct run_in_thread_traits<u&&>
{
using t = typename std::remove_reference<u>::type;
using type = t;
using ret_type = u;
static inline void assign(t& lvalue, t&& rvalue) { lvalue = rvalue; }
static inline t&& pass(t&& val) { return val; }
template<typename F> static inline t&& call(F&& fun) { return std::move(fun()); }
};
template<>
struct run_in_thread_traits<void>
{
using type = unsigned char;
using ret_type = void;
static inline void assign(unsigned char&, unsigned char&&) {}
static inline void pass(type&&) {}
template<typename F> static type call(F&& fun) { fun(); return type(0); }
};
}
template<typename F>
auto run_in_thread_sync(QObject* obj, F&& fun)
-> typename qt_impl_detail::run_in_thread_traits<decltype(std::forward<F>(fun)())>::ret_type
{
using lock_guard = std::unique_lock<std::mutex>;
using traits = qt_impl_detail::run_in_thread_traits<decltype(std::forward<F>(fun)())>;
typename traits::type ret;
struct semaphore final
{
std::mutex mtx;
std::condition_variable cvar;
bool flag;
semaphore() : flag(false) {}
void wait()
{
lock_guard guard(mtx);
while (!flag)
cvar.wait(guard);
}
void notify()
{
lock_guard guard(mtx);
flag = true;
cvar.notify_one();
}
};
semaphore sem;
{
QObject src;
QObject::connect(&src,
&QObject::destroyed,
obj,
[&]() {
traits::assign(ret, traits::call(fun));
sem.notify();
},
Qt::AutoConnection);
}
sem.wait();
return traits::pass(std::move(ret));
}
template<typename F>
void run_in_thread_async(QObject* obj, F&& fun)
{
QObject src;
QThread* t(obj->thread());
assert(t);
src.moveToThread(t);
QObject::connect(&src, &QObject::destroyed, obj, std::move(fun), Qt::AutoConnection);
}
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