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author | Marc Mutz <marc.mutz@kdab.com> | 2017-02-17 00:58:11 +0100 |
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committer | Marc Mutz <marc.mutz@kdab.com> | 2017-02-25 21:04:01 +0000 |
commit | 1d31f23ce9dd438e68aee0dbf1907e17b0d66db3 (patch) | |
tree | 65e46756713839f77d92ee54069535b7f0385b03 | |
parent | 63856135dacba615ebfabdf03be2926dc763358f (diff) | |
download | qtbase-1d31f23ce9dd438e68aee0dbf1907e17b0d66db3.tar.gz |
QVarLengthArray: add rvalue overload of append/push_back
Improves performance when appending temporaries, esp. since
the aliasing fix in the lvalue overload in 0f730ef made that
overload correct, but a bit slower across reallocs.
The unit tests already also pass rvalues, so the function is
covered in the existing tests.
[ChangeLog][QtCore][QVarLengthArray] Added rvalue overloads
of append() and push_back().
Change-Id: If3a6970f03a160cba5b42d33d32d3d18948f6ce3
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
-rw-r--r-- | src/corelib/tools/qvarlengtharray.h | 11 | ||||
-rw-r--r-- | src/corelib/tools/qvarlengtharray.qdoc | 28 |
2 files changed, 39 insertions, 0 deletions
diff --git a/src/corelib/tools/qvarlengtharray.h b/src/corelib/tools/qvarlengtharray.h index ae2c75e7df..5d0231417b 100644 --- a/src/corelib/tools/qvarlengtharray.h +++ b/src/corelib/tools/qvarlengtharray.h @@ -165,6 +165,16 @@ public: } } + void append(T &&t) { + if (s == a) + realloc(s, s << 1); + const int idx = s++; + if (QTypeInfo<T>::isComplex) + new (ptr + idx) T(std::move(t)); + else + ptr[idx] = std::move(t); + } + void append(const T *buf, int size); inline QVarLengthArray<T, Prealloc> &operator<<(const T &t) { append(t); return *this; } @@ -218,6 +228,7 @@ public: // STL compatibility: inline bool empty() const { return isEmpty(); } inline void push_back(const T &t) { append(t); } + void push_back(T &&t) { append(std::move(t)); } inline void pop_back() { removeLast(); } inline T &front() { return first(); } inline const T &front() const { return first(); } diff --git a/src/corelib/tools/qvarlengtharray.qdoc b/src/corelib/tools/qvarlengtharray.qdoc index 5e53a969e8..127afcd069 100644 --- a/src/corelib/tools/qvarlengtharray.qdoc +++ b/src/corelib/tools/qvarlengtharray.qdoc @@ -303,6 +303,34 @@ */ /*! + \fn void QVarLengthArray::append(T &&t) + \overload append + \since 5.9 + + \note Unlike the lvalue overload of append(), passing a reference to + an object that is already an element of \c *this leads to undefined + behavior: + + \code + vla.append(std::move(vla[0])); // BUG: passing an object that is already in the container + \endcode +*/ + +/*! + \fn void QVarLengthArray::push_back(T &&t) + \overload push_back + \since 5.9 + + \note Unlike the lvalue overload of push_back(), passing a reference to + an object that is already an element of \c *this leads to undefined + behavior: + + \code + vla.push_back(std::move(vla[0])); // BUG: passing an object that is already in the container + \endcode +*/ + +/*! \fn inline void QVarLengthArray::removeLast() \since 4.5 |