QtNetwork: optimize if-else conditions.

De-duplicate calls by caching results.
Reorder conditions: call cheap methods first.

Change-Id: I27715b935247c6c21bd02f9cc40655d3f9371264
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/network/access/qnetworkaccessbackend.cpp

@@ -385,15 +385,11 @@ bool QNetworkAccessBackend::start()
             // Session not ready, but can skip for loopback connections
 
             // This is not ideal.
-            const QString host = reply->url.host();
-
-            if (host == QLatin1String("localhost") ||
-                QHostAddress(host).isLoopback() ||
-                reply->url.isLocalFile()) {
-                // Don't need an open session for localhost access.
-            } else {
-                // need to wait for session to be opened
-                return false;
+            // Don't need an open session for localhost access.
+            if (!reply->url.isLocalFile()) {
+                const QString host = reply->url.host();
+                if (host != QLatin1String("localhost") && !QHostAddress(host).isLoopback())
+                    return false; // need to wait for session to be opened
             }
         }
     }

src/network/access/qnetworkcookiejar.cpp

@@ -331,7 +331,8 @@ bool QNetworkCookieJar::deleteCookie(const QNetworkCookie &cookie)
 bool QNetworkCookieJar::validateCookie(const QNetworkCookie &cookie, const QUrl &url) const
 {
     QString domain = cookie.domain();
-    if (!(isParentDomain(domain, url.host()) || isParentDomain(url.host(), domain)))
+    const QString host = url.host();
+    if (!isParentDomain(domain, host) && !isParentDomain(host, domain))
         return false; // not accepted
 
     // the check for effective TLDs makes the "embedded dot" rule from RFC 2109 section 4.3.2

src/network/access/qnetworkreplyfileimpl.cpp

@@ -88,11 +88,12 @@ QNetworkReplyFileImpl::QNetworkReplyFileImpl(QObject *parent, const QNetworkRequ
 
     QString fileName = url.toLocalFile();
     if (fileName.isEmpty()) {
-        if (url.scheme() == QLatin1String("qrc")) {
+        const QString scheme = url.scheme();
+        if (scheme == QLatin1String("qrc")) {
             fileName = QLatin1Char(':') + url.path();
         } else {
 #if defined(Q_OS_ANDROID)
-            if (url.scheme() == QLatin1String("assets"))
+            if (scheme == QLatin1String("assets"))
                 fileName = QLatin1String("assets:") + url.path();
             else
 #endif

src/network/kernel/qnetworkproxy_generic.cpp

@@ -112,16 +112,17 @@ QList<QNetworkProxy> QNetworkProxyFactory::systemProxyForQuery(const QNetworkPro
 
     if (!proxy_env.isEmpty()) {
         QUrl url = QUrl(QString::fromLocal8Bit(proxy_env));
-        if (url.scheme() == QLatin1String("socks5")) {
+        const QString scheme = url.scheme();
+        if (scheme == QLatin1String("socks5")) {
             QNetworkProxy proxy(QNetworkProxy::Socks5Proxy, url.host(),
                     url.port() ? url.port() : 1080, url.userName(), url.password());
             proxyList << proxy;
-        } else if (url.scheme() == QLatin1String("socks5h")) {
+        } else if (scheme == QLatin1String("socks5h")) {
             QNetworkProxy proxy(QNetworkProxy::Socks5Proxy, url.host(),
                     url.port() ? url.port() : 1080, url.userName(), url.password());
             proxy.setCapabilities(QNetworkProxy::HostNameLookupCapability);
             proxyList << proxy;
-        } else if ((url.scheme() == QLatin1String("http") || url.scheme().isEmpty())
+        } else if ((scheme.isEmpty() || scheme == QLatin1String("http"))
                   && query.queryType() != QNetworkProxyQuery::UdpSocket
                   && query.queryType() != QNetworkProxyQuery::TcpServer) {
             QNetworkProxy proxy(QNetworkProxy::HttpProxy, url.host(),