CEventLoop - swift's custom event loop

src/blackmisc/eventloop.h

@@ -0,0 +1,92 @@
+/* Copyright (C) 2017
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+//! \file
+
+#ifndef BLACKMISC_EVENTLOOP_H
+#define BLACKMISC_EVENTLOOP_H
+
+#include "blackmisc/blackmiscexport.h"
+
+#include <QObject>
+#include <QEventLoop>
+#include <QTimer>
+
+namespace BlackMisc
+{
+    /*!
+     * Utility class which blocks until a signal is emitted or timeout reached
+     */
+    class CEventLoop
+    {
+    public:
+        //! Deleted constructor
+        CEventLoop() = delete;
+
+        //! Wait for the given time, while processing events.
+        static void processEventsFor(int timeoutMs)
+        {
+            QEventLoop eventLoop;
+            QTimer::singleShot(timeoutMs, &eventLoop, &QEventLoop::quit);
+            eventLoop.exec();
+        }
+
+        //! Block, but keep processing events, until sender emits the signal or the timeout expires.
+        //! Return true if the signal was emitted, false if the timeout expired.
+        template <typename T, typename F>
+        static bool processEventsUntil(const T *sender, F signal, int timeoutMs)
+        {
+            return processEventsUntil(sender, signal, timeoutMs, [] {});
+        }
+
+        //! Overloaded version that executes an initial function after connecting the signal.
+        //! If the function's return type is convertible to bool, and it evaluates to true,
+        //! then the waiting will immediately time out and return true.
+        template <typename T, typename F1, typename F2>
+        #ifdef Q_CC_MINGW
+        __attribute__((noinline)) // work around an apparent GCC 5.3 PE/COFF codegen bug
+        #endif
+        static bool processEventsUntil(const T *sender, F1 signal, int timeoutMs, F2 init)
+        {
+            QEventLoop eventLoop;
+            bool result = false;
+            QObject::connect(sender, signal, &eventLoop, [ & ]
+            {
+                result = true;
+                eventLoop.quit();
+            });
+            if (checkInit(init))
+            {
+                return true;
+            }
+            if (timeoutMs > 0)
+            {
+                QTimer::singleShot(timeoutMs, &eventLoop, &QEventLoop::quit);
+            }
+            eventLoop.exec();
+            return result;
+        }
+
+    private:
+        template <typename F>
+        static bool checkInit(F init, std::enable_if_t<std::is_void<decltype(init())>::value, int> = 0)
+        {
+            init();
+            return false;
+        }
+
+        template <typename F>
+        static bool checkInit(F init, std::enable_if_t<!std::is_void<decltype(init())>::value, int> = 0)
+        {
+            return init();
+        }
+    };
+} // ns
+
+#endif // guard