Improve removeIf() to support set types

We can now replace QMutable*Iterator by removeIf() which usage is more consistent with other
algorithm functions.

src/base/algorithm.h

@@ -28,14 +28,42 @@
 
 #pragma once
 
-namespace Dict
+#include <type_traits>
+
+namespace Algorithm
 {
-    // To be used with QMap, QHash and it's variants
-    template <typename Dictionary, typename BinaryPredicate>
-    void removeIf(Dictionary &&dict, BinaryPredicate p)
+    template <typename ...>
+    using void_t = void;  // replace this with std::void_t in C++17
+
+    template <typename T, typename = void>
+    struct HasMappedType
+        : std::false_type
+    {
+    };
+
+    template <typename T>
+    struct HasMappedType<T, void_t<typename T::mapped_type>>
+        : std::true_type
+    {
+    };
+
+    // To be used with associative array types, such as QMap, QHash and it's variants
+    template <typename T, typename BinaryPredicate
+        , typename std::enable_if_t<HasMappedType<T>::value, int> = 0>
+    void removeIf(T &dict, BinaryPredicate p)
     {
         auto it = dict.begin();
         while (it != dict.end())
-            it = (p(it.key(), it.value()) ? dict.erase(it) : it + 1);
+            it = (p(it.key(), it.value()) ? dict.erase(it) : (it + 1));
+    }
+
+    // To be used with set types, such as QSet, std::set
+    template <typename T, typename UnaryPredicate
+        , typename std::enable_if_t<!HasMappedType<T>::value, int> = 0>
+    void removeIf(T &set, UnaryPredicate p)
+    {
+        auto it = set.begin();
+        while (it != set.end())
+            it = (p(*it) ? set.erase(it) : (it + 1));
     }
 }

src/base/bittorrent/session.cpp

@@ -754,7 +754,7 @@ bool Session::removeCategory(const QString &name)
     if (isSubcategoriesEnabled()) {
         // remove subcategories
         const QString test = name + '/';
-        Dict::removeIf(m_categories, [this, &test, &result](const QString &category, const QString &)
+        Algorithm::removeIf(m_categories, [this, &test, &result](const QString &category, const QString &)
         {
             if (category.startsWith(test)) {
                 result = true;

src/base/filesystemwatcher.cpp

@@ -122,7 +122,7 @@ void FileSystemWatcher::processPartialTorrents()
     QStringList noLongerPartial;
 
     // Check which torrents are still partial
-    Dict::removeIf(m_partialTorrents, [&noLongerPartial](const QString &torrentPath, int &value)
+    Algorithm::removeIf(m_partialTorrents, [&noLongerPartial](const QString &torrentPath, int &value)
     {
         if (!QFile::exists(torrentPath))
             return true;

src/base/http/server.cpp

@@ -32,7 +32,6 @@
 
 #include <algorithm>
 
-#include <QMutableListIterator>
 #include <QNetworkProxy>
 #include <QSslCipher>
 #include <QSslConfiguration>
@@ -40,6 +39,7 @@
 #include <QStringList>
 #include <QTimer>
 
+#include "base/algorithm.h"
 #include "base/utils/net.h"
 #include "connection.h"
 
@@ -119,14 +119,14 @@ void Server::removeConnection(Connection *connection)
 
 void Server::dropTimedOutConnection()
 {
-    QMutableSetIterator<Connection *> i(m_connections);
-    while (i.hasNext()) {
-        Connection *connection = i.next();
-        if (connection->hasExpired(KEEP_ALIVE_DURATION)) {
-            connection->deleteLater();
-            i.remove();
-        }
-    }
+    Algorithm::removeIf(m_connections, [](Connection *connection)
+    {
+        if (!connection->hasExpired(KEEP_ALIVE_DURATION))
+            return false;
+
+        connection->deleteLater();
+        return true;
+    });
 }
 
 bool Server::setupHttps(const QByteArray &certificates, const QByteArray &privateKey)

src/base/preferences.cpp

@@ -31,7 +31,6 @@
 
 #include <QDir>
 #include <QLocale>
-#include <QMutableListIterator>
 #include <QSettings>
 
 #ifndef DISABLE_GUI
@@ -49,6 +48,7 @@
 #include <CoreServices/CoreServices.h>
 #endif
 
+#include "algorithm.h"
 #include "global.h"
 #include "settingsstorage.h"
 #include "utils/fs.h"
@@ -516,13 +516,12 @@ QList<Utils::Net::Subnet> Preferences::getWebUiAuthSubnetWhitelist() const
 
 void Preferences::setWebUiAuthSubnetWhitelist(QStringList subnets)
 {
-    QMutableListIterator<QString> i(subnets);
-    while (i.hasNext()) {
+    Algorithm::removeIf(subnets, [](const QString &subnet)
+    {
         bool ok = false;
-        const Utils::Net::Subnet subnet = Utils::Net::parseSubnet(i.next().trimmed(), &ok);
-        if (!ok)
-            i.remove();
-    }
+        Utils::Net::parseSubnet(subnet.trimmed(), &ok);
+        return !ok;
+    });
 
     setValue("Preferences/WebUI/AuthSubnetWhitelist", subnets);
 }