From 889d40ebe2d9d0e92caea2749608720f7c088173 Mon Sep 17 00:00:00 2001 From: Giuseppe D'Angelo Date: Fri, 3 Jan 2020 17:18:02 +0100 Subject: Centralize the implementation of move assignment operators At the moment we have two main strategies for dealing with move assignment in Qt: 1) move-and-swap, used by "containers" (in the broad sense): containers, but also smart pointers and similar classes that can hold user-defined types; 2) pure swap, used by containers that hold only memory (e.g. QString, QByteArray, ...) as well as most implicitly shared datatypes. Given the fact that a move assignment operator's code is just boilerplate (whether it's move-and-swap or pure swap), provide two _strictly internal_ macros to help write them, and apply the macros across corelib and gui, porting away from the hand-rolled implementations. The rule of thumb when porting to the new macros is: * Try to stick to the existing code behavior, unless broken * if changing, then follow this checklist: * if the class does not have a move constructor => pure swap (but consider ADDING a move constructor, if possible!) * if the class does have a move constructor, try to follow the criteria above, namely: * if the class holds only memory, pure swap; * if the class may hold anything else but memory (file handles, etc.), then move and swap. Noteworthy details: * some operators planned to be removed in Qt 6 were not ported; * as drive-by, some move constructors were simplified to be using qExchange(); others were outright broken and got fixed; * some contained some more interesting code and were not touched. Change-Id: Idaab3489247dcbabb6df3fa1e5286b69e1d372e9 Reviewed-by: Allan Sandfeld Jensen --- src/corelib/text/qbytearray.h | 3 +-- src/corelib/text/qcollator.h | 6 ++---- src/corelib/text/qlocale.h | 2 +- src/corelib/text/qregularexpression.h | 3 +-- src/corelib/text/qstring.h | 3 +-- 5 files changed, 6 insertions(+), 11 deletions(-) (limited to 'src/corelib/text') diff --git a/src/corelib/text/qbytearray.h b/src/corelib/text/qbytearray.h index 8f5e1d9f7f..60f1bd01f5 100644 --- a/src/corelib/text/qbytearray.h +++ b/src/corelib/text/qbytearray.h @@ -170,8 +170,7 @@ public: QByteArray &operator=(const char *str); inline QByteArray(QByteArray && other) noexcept { qSwap(d, other.d); } - inline QByteArray &operator=(QByteArray &&other) noexcept - { qSwap(d, other.d); return *this; } + QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QByteArray) inline void swap(QByteArray &other) noexcept { qSwap(d, other.d); } diff --git a/src/corelib/text/qcollator.h b/src/corelib/text/qcollator.h index de8c8b7e3c..793d1cedd4 100644 --- a/src/corelib/text/qcollator.h +++ b/src/corelib/text/qcollator.h @@ -57,8 +57,7 @@ public: QCollatorSortKey(const QCollatorSortKey &other); ~QCollatorSortKey(); QCollatorSortKey &operator=(const QCollatorSortKey &other); - inline QCollatorSortKey &operator=(QCollatorSortKey &&other) noexcept - { swap(other); return *this; } + QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QCollatorSortKey) void swap(QCollatorSortKey &other) noexcept { d.swap(other.d); } @@ -88,8 +87,7 @@ public: QCollator &operator=(const QCollator &); QCollator(QCollator &&other) noexcept : d(other.d) { other.d = nullptr; } - QCollator &operator=(QCollator &&other) noexcept - { swap(other); return *this; } + QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QCollator) void swap(QCollator &other) noexcept { qSwap(d, other.d); } diff --git a/src/corelib/text/qlocale.h b/src/corelib/text/qlocale.h index 0ff2e4d469..8b49eb89f9 100644 --- a/src/corelib/text/qlocale.h +++ b/src/corelib/text/qlocale.h @@ -944,7 +944,7 @@ public: QLocale(Language language, Country country = AnyCountry); QLocale(Language language, Script script, Country country); QLocale(const QLocale &other); - QLocale &operator=(QLocale &&other) noexcept { swap(other); return *this; } + QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QLocale) QLocale &operator=(const QLocale &other); ~QLocale(); diff --git a/src/corelib/text/qregularexpression.h b/src/corelib/text/qregularexpression.h index ee6c421399..6067d94c76 100644 --- a/src/corelib/text/qregularexpression.h +++ b/src/corelib/text/qregularexpression.h @@ -88,8 +88,7 @@ public: QRegularExpression(const QRegularExpression &re); ~QRegularExpression(); QRegularExpression &operator=(const QRegularExpression &re); - QRegularExpression &operator=(QRegularExpression &&re) noexcept - { d.swap(re.d); return *this; } + QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QRegularExpression) void swap(QRegularExpression &other) noexcept { d.swap(other.d); } diff --git a/src/corelib/text/qstring.h b/src/corelib/text/qstring.h index ea78dd017f..0e564b20ed 100644 --- a/src/corelib/text/qstring.h +++ b/src/corelib/text/qstring.h @@ -337,8 +337,7 @@ public: QString &operator=(QLatin1String latin1); inline QString(QString &&other) noexcept { qSwap(d, other.d); } - inline QString &operator=(QString &&other) noexcept - { qSwap(d, other.d); return *this; } + QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QString) inline void swap(QString &other) noexcept { qSwap(d, other.d); } inline qsizetype size() const { return d.size; } inline qsizetype count() const { return d.size; } -- cgit v1.2.3