src/base/algorithm.h

   1 /*
   2  * Bittorrent Client using Qt and libtorrent.
   3  * Copyright (C) 2018  Vladimir Golovnev <glassez@yandex.ru>
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version 2
   8  * of the License, or (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  18  *
  19  * In addition, as a special exception, the copyright holders give permission to
  20  * link this program with the OpenSSL project's "OpenSSL" library (or with
  21  * modified versions of it that use the same license as the "OpenSSL" library),
  22  * and distribute the linked executables. You must obey the GNU General Public
  23  * License in all respects for all of the code used other than "OpenSSL".  If you
  24  * modify file(s), you may extend this exception to your version of the file(s),
  25  * but you are not obligated to do so. If you do not wish to do so, delete this
  26  * exception statement from your version.
  27  */
  28
  29 #pragma once
  30
  31 #include <type_traits>
  32
  33 namespace Algorithm
  34 {
  35     template <typename T, typename = void>
  36     struct HasMappedType
  37         : std::false_type
  38     {
  39     };
  40
  41     template <typename T>
  42     struct HasMappedType<T, std::void_t<typename T::mapped_type>>
  43         : std::true_type
  44     {
  45     };
  46
  47     // To be used with associative array types, such as QMap, QHash and its variants
  48     template <typename T, typename BinaryPredicate
  49         , typename std::enable_if_t<HasMappedType<T>::value, int> = 0>
  50     void removeIf(T &dict, BinaryPredicate &&p)
  51     {
  52         auto it = dict.begin();
  53         while (it != dict.end())
  54             it = (p(it.key(), it.value()) ? dict.erase(it) : ++it);
  55     }
  56
  57     // To be used with set types, such as QSet, std::set
  58     template <typename T, typename UnaryPredicate
  59         , typename std::enable_if_t<!HasMappedType<T>::value, int> = 0>
  60     void removeIf(T &set, UnaryPredicate &&p)
  61     {
  62         auto it = set.begin();
  63         while (it != set.end())
  64             it = (p(*it) ? set.erase(it) : ++it);
  65     }
  66 }