1 files changed, 84 insertions, 0 deletions
diff --git a/src/corelib/global/qforeach.h b/src/corelib/global/qforeach.h
new file mode 100644
index 0000000000..ab0e20b989
--- /dev/null
+++ b/src/corelib/global/qforeach.h
@@ -0,0 +1,84 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// Copyright (C) 2019 Intel Corporation.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QFOREACH_H
+#define QFOREACH_H
+
+#include <QtCore/qtclasshelpermacros.h>
+#include <QtCore/qtconfigmacros.h>
+#include <QtCore/qtdeprecationmarkers.h>
+#include <QtCore/qttypetraits.h>
+
+QT_BEGIN_NAMESPACE
+
+#if 0
+#pragma qt_class(QForeach)
+#pragma qt_sync_stop_processing
+#endif
+
+#ifndef QT_NO_FOREACH
+
+namespace QtPrivate {
+
+template <typename T>
+class QForeachContainer {
+    Q_DISABLE_COPY_MOVE(QForeachContainer)
+public:
+    QForeachContainer(const T &t) : c(t), i(std::as_const(c).begin()), e(std::as_const(c).end()) {}
+    QForeachContainer(T &&t) : c(std::move(t)), i(std::as_const(c).begin()), e(std::as_const(c).end())  {}
+
+    T c;
+    typename T::const_iterator i, e;
+};
+
+// Containers that have a detach function are considered shared, and are OK in a foreach loop
+template <typename T, typename = decltype(std::declval<T>().detach())>
+inline void warnIfContainerIsNotShared(int) {}
+
+#if QT_DEPRECATED_SINCE(6, 0)
+// Other containers will copy themselves if used in foreach, this use is deprecated
+template <typename T>
+QT_DEPRECATED_VERSION_X_6_0("Do not use foreach/Q_FOREACH with containers which are not implicitly shared. "
+    "Prefer using a range-based for loop with these containers: `for (const auto &it : container)`, "
+    "keeping in mind that range-based for doesn't copy the container as Q_FOREACH does")
+inline void warnIfContainerIsNotShared(...) {}
+#endif
+
+template<typename T>
+QForeachContainer<typename std::decay<T>::type> qMakeForeachContainer(T &&t)
+{
+    warnIfContainerIsNotShared<typename std::decay<T>::type>(0);
+    return QForeachContainer<typename std::decay<T>::type>(std::forward<T>(t));
+}
+
+}
+
+// Use C++17 if statement with initializer. User's code ends up in a else so
+// scoping of different ifs is not broken
+#define Q_FOREACH_IMPL(variable, name, container)                                             \
+    for (auto name = QtPrivate::qMakeForeachContainer(container); name.i != name.e; ++name.i) \
+        if (variable = *name.i; false) {} else
+
+#define Q_FOREACH_JOIN(A, B) Q_FOREACH_JOIN_IMPL(A, B)
+#define Q_FOREACH_JOIN_IMPL(A, B) A ## B
+
+#define Q_FOREACH(variable, container) \
+    Q_FOREACH_IMPL(variable, Q_FOREACH_JOIN(_container_, __LINE__), container)
+#endif // QT_NO_FOREACH
+
+#define Q_FOREVER for(;;)
+#ifndef QT_NO_KEYWORDS
+# ifndef QT_NO_FOREACH
+#  ifndef foreach
+#    define foreach Q_FOREACH
+#  endif
+# endif // QT_NO_FOREACH
+#  ifndef forever
+#    define forever Q_FOREVER
+#  endif
+#endif
+
+QT_END_NAMESPACE
+
+#endif /* QFOREACH_H */