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Diffstat (limited to 'src/corelib/global/q20map.h')
-rw-r--r-- | src/corelib/global/q20map.h | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/src/corelib/global/q20map.h b/src/corelib/global/q20map.h new file mode 100644 index 0000000000..c719067480 --- /dev/null +++ b/src/corelib/global/q20map.h @@ -0,0 +1,72 @@ +// Copyright (C) 2023 Ahmad Samir <a.samirh78@gmail.com> +// Copyright (C) 2023 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 Q20MAP_H +#define Q20MAP_H + +#include <QtCore/qtconfigmacros.h> + +#include <map> +#if __has_include(<memory_resource>) +# include <memory_resource> +#endif + +// +// 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 + +namespace q20 { +// like std::erase/std::erase_if for std::map +#if defined(__cpp_lib_erase_if) && __cpp_lib_erase_if >= 202002L // the one returning size_type +using std::erase_if; +#else + +// Make it more specialized than the compiler's, so that our implementation is preferred over +// the compiler's (which may be present, but return void instead of the number of erased elements). + +#define MAKE_OVERLOAD(map, allocator) \ + template <typename Key, typename T, typename Compare, typename Pred> \ + constexpr typename std::map<Key, T, Compare, std::allocator<std::pair<const Key, T>>>::size_type \ + erase_if(std::map<Key, T, Compare, std::allocator<std::pair<const Key, T>>> &c, Pred p) \ + { \ + const auto origSize = c.size(); \ + for (auto it = c.begin(), end = c.end(); it != end; /* erasing */) { \ + if (p(*it)) \ + it = c.erase(it); \ + else \ + ++it; \ + } \ + return origSize - c.size(); \ + } \ + /* end */ + +MAKE_OVERLOAD(map, allocator) +MAKE_OVERLOAD(multimap, allocator) +#ifdef __cpp_lib_polymorphic_allocator +MAKE_OVERLOAD(map, pmr::polymorphic_allocator) +MAKE_OVERLOAD(multimap, pmr::polymorphic_allocator) +#endif // __cpp_lib_polymorphic_allocator + +#undef MAKE_OVERLOAD + +#endif // __cpp_lib_erase_if +} // namespace q20 + +QT_END_NAMESPACE + +#endif /* Q20MAP_H */ |