| 1 | // Copyright (C) 2022 The Qt Company Ltd. |
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| 2 | // Copyright (C) 2019 Intel Corporation. |
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| 3 | // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only |
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| 4 | |
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| 5 | #ifndef QFOREACH_H |
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| 6 | #define QFOREACH_H |
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| 7 | |
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| 8 | #include <QtCore/qtclasshelpermacros.h> |
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| 9 | #include <QtCore/qtconfigmacros.h> |
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| 10 | #include <QtCore/qtdeprecationmarkers.h> |
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| 11 | #include <QtCore/qttypetraits.h> |
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| 12 | |
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| 13 | QT_BEGIN_NAMESPACE |
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| 14 | |
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| 15 | #if 0 |
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| 16 | #pragma qt_class(QForeach) |
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| 17 | #pragma qt_sync_stop_processing |
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| 18 | #endif |
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| 19 | |
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| 20 | #ifndef QT_NO_FOREACH |
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| 21 | |
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| 22 | namespace QtPrivate { |
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| 23 | |
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| 24 | template <typename T> |
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| 25 | class QForeachContainer { |
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| 26 | Q_DISABLE_COPY_MOVE(QForeachContainer) |
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| 27 | public: |
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| 28 | QForeachContainer(const T &t) : c(t), i(std::as_const(c).begin()), e(std::as_const(c).end()) {} |
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| 29 | QForeachContainer(T &&t) : c(std::move(t)), i(std::as_const(c).begin()), e(std::as_const(c).end()) {} |
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| 30 | |
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| 31 | T c; |
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| 32 | typename T::const_iterator i, e; |
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| 33 | }; |
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| 34 | |
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| 35 | // Containers that have a detach function are considered shared, and are OK in a foreach loop |
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| 36 | template <typename T, typename = decltype(std::declval<T>().detach())> |
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| 37 | inline void warnIfContainerIsNotShared(int) {} |
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| 38 | |
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| 39 | #if QT_DEPRECATED_SINCE(6, 0) |
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| 40 | // Other containers will copy themselves if used in foreach, this use is deprecated |
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| 41 | template <typename T> |
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| 42 | QT_DEPRECATED_VERSION_X_6_0("Do not use foreach/Q_FOREACH with containers which are not implicitly shared. " |
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| 43 | "Prefer using a range-based for loop with these containers: `for (const auto &it : container)`, " |
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| 44 | "keeping in mind that range-based for doesn't copy the container as Q_FOREACH does" ) |
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| 45 | inline void warnIfContainerIsNotShared(...) {} |
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| 46 | #endif |
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| 47 | |
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| 48 | template<typename T> |
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| 49 | QForeachContainer<typename std::decay<T>::type> qMakeForeachContainer(T &&t) |
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| 50 | { |
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| 51 | warnIfContainerIsNotShared<typename std::decay<T>::type>(0); |
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| 52 | return QForeachContainer<typename std::decay<T>::type>(std::forward<T>(t)); |
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| 53 | } |
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| 54 | |
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| 55 | } |
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| 56 | |
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| 57 | // Use C++17 if statement with initializer. User's code ends up in a else so |
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| 58 | // scoping of different ifs is not broken |
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| 59 | #define Q_FOREACH_IMPL(variable, name, container) \ |
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| 60 | for (auto name = QtPrivate::qMakeForeachContainer(container); name.i != name.e; ++name.i) \ |
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| 61 | if (variable = *name.i; false) {} else |
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| 62 | |
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| 63 | #define Q_FOREACH_JOIN(A, B) Q_FOREACH_JOIN_IMPL(A, B) |
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| 64 | #define Q_FOREACH_JOIN_IMPL(A, B) A ## B |
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| 65 | |
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| 66 | #define Q_FOREACH(variable, container) \ |
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| 67 | Q_FOREACH_IMPL(variable, Q_FOREACH_JOIN(_container_, __LINE__), container) |
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| 68 | #endif // QT_NO_FOREACH |
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| 69 | |
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| 70 | #define Q_FOREVER for(;;) |
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| 71 | #ifndef QT_NO_KEYWORDS |
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| 72 | # ifndef QT_NO_FOREACH |
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| 73 | # ifndef foreach |
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| 74 | # define foreach Q_FOREACH |
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| 75 | # endif |
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| 76 | # endif // QT_NO_FOREACH |
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| 77 | # ifndef forever |
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| 78 | # define forever Q_FOREVER |
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| 79 | # endif |
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| 80 | #endif |
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| 81 | |
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| 82 | QT_END_NAMESPACE |
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| 83 | |
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| 84 | #endif /* QFOREACH_H */ |
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| 85 | |
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