qBittorrent/src/base/algorithm.h
Luís Pereira ac42ccb5e4
Don't create temporary containers just to iterate over them
Stops temporary containers being created needlessly due to API misuse.
For example, it’s common for developers to assume QHash::values() and
QHash::keys() are free and abuse them, failing to realize their
implementation internally actually iterates the whole container, allocates
memory, and fills a new QList.

Added a removeIf generic algorithm, similar to std ones. We can't use std
algorithms with Qt dictionaries because Qt iterators have different
behavior from the std ones.

Found using clazy.
2018-03-18 16:22:12 +03:00

41 lines
1.7 KiB
C++

/*
* Bittorrent Client using Qt and libtorrent.
* Copyright (C) 2018 Vladimir Golovnev <glassez@yandex.ru>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* In addition, as a special exception, the copyright holders give permission to
* link this program with the OpenSSL project's "OpenSSL" library (or with
* modified versions of it that use the same license as the "OpenSSL" library),
* and distribute the linked executables. You must obey the GNU General Public
* License in all respects for all of the code used other than "OpenSSL". If you
* modify file(s), you may extend this exception to your version of the file(s),
* but you are not obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*/
#pragma once
namespace Dict
{
// To be used with QMap, QHash and it's variants
template <typename Dictionary, typename BinaryPredicate>
void removeIf(Dictionary &&dict, BinaryPredicate p)
{
auto it = dict.begin();
while (it != dict.end())
it = (p(it.key(), it.value()) ? dict.erase(it) : it + 1);
}
}