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Diffstat (limited to 'src/corelib/global/q20iterator.h')
-rw-r--r-- | src/corelib/global/q20iterator.h | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/src/corelib/global/q20iterator.h b/src/corelib/global/q20iterator.h new file mode 100644 index 0000000000..9ed4d69965 --- /dev/null +++ b/src/corelib/global/q20iterator.h @@ -0,0 +1,54 @@ +// Copyright (C) 2021 The Qt Company Ltd. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only +#ifndef Q20ITERATOR_H +#define Q20ITERATOR_H + +#include <QtCore/qglobal.h> + +#include <iterator> + +// +// W A R N I N G +// ------------- +// +// This file is not part of the Qt API. Types and functions defined in this +// file can reliably be replaced by their std counterparts, once available. +// You may use these definitions in your own code, but be aware that we +// will remove them once Qt depends on the C++ version that supports +// them in namespace std. There will be NO deprecation warning, the +// definitions will JUST go away. +// +// If you can't agree to these terms, don't use these definitions! +// +// We mean it. +// + +QT_BEGIN_NAMESPACE + +// like std::ssize +namespace q20 { +#ifdef __cpp_lib_ssize + using std::ssize; +#else + template<class C> constexpr auto ssize(const C &c) + -> std::common_type_t<std::ptrdiff_t, std::make_signed_t<decltype(c.size())>> + { return static_cast<std::common_type_t<std::ptrdiff_t, std::make_signed_t<decltype(c.size())>>>(c.size()); } + + template<class T, std::ptrdiff_t N> constexpr std::ptrdiff_t ssize(const T (&)[N]) noexcept + { return N; } +#endif +} // namespace q20 + +// like q20::iter_reference_t +namespace q20 { +#ifdef __cpp_lib_ranges + using std::iter_reference_t; +#else + template <typename Dereferencable> // unconstrained (constraint requires concepts) + using iter_reference_t = decltype(*std::declval<Dereferencable&>()); +#endif // __cpp_lib_ranges +} // namespace q20 + +QT_END_NAMESPACE + +#endif /* Q20ITERATOR_H */ |