diff options
author | Thorbjørn Martsum <tmartsum@gmail.com> | 2013-01-10 19:42:59 +0100 |
---|---|---|
committer | The Qt Project <gerrit-noreply@qt-project.org> | 2013-03-07 08:37:26 +0100 |
commit | 3222db0937aaf1ae5681bc124406ec37f550bc7c (patch) | |
tree | 3c26a72d5a7838706266e2c02a05d35c85622d83 /src/corelib/tools | |
parent | ab52e722926d495e29263e59a466ad5ff0106275 (diff) |
QVector - removeLast optimize
In case somebody uses QVector as a stack, it is not fair to have
takeLast, removeLast and pop_back to do way too much work.
This is still very slow compared to std::vector::pop_back
(mostly due implicit sharing), however it is more than a
factor faster than before.
Change-Id: I636872675e80c8ca0c8ebc94b04f587a2dcd6d8d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src/corelib/tools')
-rw-r--r-- | src/corelib/tools/qvector.h | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/src/corelib/tools/qvector.h b/src/corelib/tools/qvector.h index e2c28e4060..a06fb7b4eb 100644 --- a/src/corelib/tools/qvector.h +++ b/src/corelib/tools/qvector.h @@ -139,7 +139,7 @@ public: void remove(int i); void remove(int i, int n); inline void removeFirst() { Q_ASSERT(!isEmpty()); erase(d->begin()); } - inline void removeLast() { Q_ASSERT(!isEmpty()); erase(d->end() - 1); } + inline void removeLast(); inline T takeFirst() { Q_ASSERT(!isEmpty()); T r = first(); removeFirst(); return r; } inline T takeLast() { Q_ASSERT(!isEmpty()); T r = last(); removeLast(); return r; } @@ -558,6 +558,22 @@ void QVector<T>::append(const T &t) } template <typename T> +inline void QVector<T>::removeLast() +{ + Q_ASSERT(!isEmpty()); + + if (d->alloc) { + if (d->ref.isShared()) { + reallocData(d->size - 1, int(d->alloc)); + return; + } + if (QTypeInfo<T>::isComplex) + (d->data() + d->size - 1)->~T(); + --d->size; + } +} + +template <typename T> typename QVector<T>::iterator QVector<T>::insert(iterator before, size_type n, const T &t) { int offset = std::distance(d->begin(), before); @@ -606,6 +622,7 @@ typename QVector<T>::iterator QVector<T>::erase(iterator abegin, iterator aend) // FIXME we could do a proper realloc, which copy constructs only needed data. // FIXME we ara about to delete data maybe it is good time to shrink? + // FIXME the shrink is also an issue in removeLast, that is just a copy + reduce of this. if (d->alloc) { detach(); abegin = d->begin() + itemsUntouched; |