Optimize string usage

Use QStringBuilder more.
Use QL1S directly, without QString construction.

Change-Id: Iad844391367681fc1013b9725403d009e7c346e6
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/kernel/qmetaobject.cpp

@@ -1353,7 +1353,7 @@ static inline QByteArray findMethodCandidates(const QMetaObject *metaObject, con
     for (int i = 0; i < metaObject->methodCount(); ++i) {
         const QMetaMethod method = metaObject->method(i);
         if (method.name() == memberByteArray)
-            candidateMessage.append("    " + method.methodSignature() + '\n');
+            candidateMessage += "    " + method.methodSignature() + '\n';
     }
     if (!candidateMessage.isEmpty()) {
         candidateMessage.prepend("\nCandidates are:\n");

src/gui/text/qtextdocumentfragment.cpp

@@ -428,7 +428,7 @@ QTextHtmlImporter::QTextHtmlImporter(QTextDocument *_doc, const QString &_html,
     QString html = _html;
     const int startFragmentPos = html.indexOf(QLatin1String("<!--StartFragment-->"));
     if (startFragmentPos != -1) {
-        QString qt3RichTextHeader(QLatin1String("<meta name=\"qrichtext\" content=\"1\" />"));
+        const QLatin1String qt3RichTextHeader("<meta name=\"qrichtext\" content=\"1\" />");
 
         // Hack for Qt3
         const bool hasQtRichtextMetaTag = html.contains(qt3RichTextHeader);

src/gui/text/qtexthtmlparser.cpp

@@ -1438,9 +1438,7 @@ static void setWidthAttribute(QTextLength *width, const QString &valueStr)
 #ifndef QT_NO_CSSPARSER
 void QTextHtmlParserNode::parseStyleAttribute(const QString &value, const QTextDocument *resourceProvider)
 {
-    QString css = value;
+    const QString css = QLatin1String("* {") + value + QLatin1Char('}');
-    css.prepend(QLatin1String("* {"));
-    css.append(QLatin1Char('}'));
     QCss::Parser parser(css);
     QCss::StyleSheet sheet;
     parser.parse(&sheet, Qt::CaseInsensitive);

src/network/access/qnetworkaccessftpbackend.cpp

@@ -306,8 +306,6 @@ void QNetworkAccessFtpBackend::ftpDone()
         state = CheckingFeatures;
         if (operation() == QNetworkAccessManager::GetOperation) {
             // send help command to find out if server supports "SIZE" and "MDTM"
-            QString command = url().path();
-            command.prepend(QLatin1String("%1 "));
             helpId = ftp->rawCommand(QLatin1String("HELP")); // get supported commands
         } else {
             ftpDone();
@@ -316,14 +314,13 @@ void QNetworkAccessFtpBackend::ftpDone()
         state = Statting;
         if (operation() == QNetworkAccessManager::GetOperation) {
             // logged in successfully, send the stat requests (if supported)
-            QString command = url().path();
+            const QString path = url().path();
-            command.prepend(QLatin1String("%1 "));
             if (supportsSize) {
                 ftp->rawCommand(QLatin1String("TYPE I"));
-                sizeId = ftp->rawCommand(command.arg(QLatin1String("SIZE"))); // get size
+                sizeId = ftp->rawCommand(QLatin1String("SIZE ") + path); // get size
             }
             if (supportsMdtm)
-                mdtmId = ftp->rawCommand(command.arg(QLatin1String("MDTM"))); // get modified time
+                mdtmId = ftp->rawCommand(QLatin1String("MDTM ") + path); // get modified time
             if (!supportsSize && !supportsMdtm)
                 ftpDone();      // no commands sent, move to the next state
         } else {

src/tools/uic/cpp/cppwriteinitialization.cpp

@@ -1255,14 +1255,14 @@ void WriteInitialization::writeProperties(const QString &varName,
         QString setFunction;
 
         if (stdset) {
-            setFunction = QLatin1String("->set");
+            setFunction = QLatin1String("->set")
-            setFunction += propertyName.left(1).toUpper();
+                        + propertyName.left(1).toUpper()
-            setFunction += propertyName.mid(1);
+                        + propertyName.midRef(1)
-            setFunction += QLatin1Char('(');
+                        + QLatin1Char('(');
         } else {
-            setFunction = QLatin1String("->setProperty(\"");
+            setFunction += QLatin1String("->setProperty(\"")
-            setFunction += propertyName;
+                         + propertyName
-            setFunction += QLatin1String("\", QVariant");
+                         + QLatin1String("\", QVariant");
             if (p->kind() == DomProperty::Enum)
                 setFunction += QLatin1String("::fromValue");
             setFunction += QLatin1Char('(');
@@ -1286,9 +1286,9 @@ void WriteInitialization::writeProperties(const QString &varName,
                 if (stdset)
                     propertyValue = fixString(p->elementCstring(), m_dindent);
                 else {
-                    propertyValue = QLatin1String("QByteArray(");
+                    propertyValue = QLatin1String("QByteArray(")
-                    propertyValue += fixString(p->elementCstring(), m_dindent);
+                                  + fixString(p->elementCstring(), m_dindent)
-                    propertyValue += QLatin1Char(')');
+                                  + QLatin1Char(')');
                 }
             }
             break;
@@ -1304,11 +1304,8 @@ void WriteInitialization::writeProperties(const QString &varName,
             break;
         case DomProperty::Enum:
             propertyValue = p->elementEnum();
-            if (!propertyValue.contains(QLatin1String("::"))) {
+            if (!propertyValue.contains(QLatin1String("::")))
-                QString scope  = className;
+                propertyValue = className + QLatin1String("::") + propertyValue;
-                scope += QLatin1String("::");
-                propertyValue.prepend(scope);
-            }
             break;
         case DomProperty::Set:
             propertyValue = p->elementSet();
@@ -1898,31 +1895,29 @@ QString WriteInitialization::pixCall(const QString &t, const QString &text) cons
         if (m_option.extractImages) {
             const QString format = image->elementData()->attributeFormat();
             const QString extension = format.left(format.indexOf(QLatin1Char('.'))).toLower();
-            QString rc = QLatin1String("QPixmap(QString::fromUtf8(\":/");
+            return QLatin1String("QPixmap(QString::fromUtf8(\":/")
-            rc += m_generatedClass;
+                 + m_generatedClass
-            rc += QLatin1String("/images/");
+                 + QLatin1String("/images/")
-            rc += text;
+                 + text
-            rc += QLatin1Char('.');
+                 + QLatin1Char('.')
-            rc += extension;
+                 + extension
-            rc += QLatin1String("\"))");
+                 + QLatin1String("\"))");
-            return rc;
         }
-        QString rc = WriteIconInitialization::iconFromDataFunction();
+        return WriteIconInitialization::iconFromDataFunction()
-        rc += QLatin1Char('(');
+             + QLatin1Char('(')
-        rc += text;
+             + text
-        rc += QLatin1String("_ID)");
+             + QLatin1String("_ID)");
-        return rc;
     }
 
     QString pixFunc = m_uic->pixmapFunction();
     if (pixFunc.isEmpty())
         pixFunc = QLatin1String("QString::fromUtf8");
 
-    type += QLatin1Char('(');
+    type += QLatin1Char('(')
-    type += pixFunc;
+          + pixFunc
-    type += QLatin1Char('(');
+          + QLatin1Char('(')
-    type += fixString(text, m_dindent);
+          + fixString(text, m_dindent)
-    type += QLatin1String("))");
+          + QLatin1String("))");
     return type;
 }
 
@@ -2316,23 +2311,20 @@ QString WriteInitialization::trCall(const QString &str, const QString &commentHi
 
     if (m_option.translateFunction.isEmpty()) {
         if (m_option.idBased) {
-            result = QLatin1String("qtTrId(");
+            result += QLatin1String("qtTrId(");
         } else {
-            result = QLatin1String("QApplication::translate(\"");
+            result += QLatin1String("QApplication::translate(\"")
-            result += m_generatedClass;
+                    + m_generatedClass
-            result += QLatin1Char('"');
+                    + QLatin1String("\", ");
-            result += QLatin1String(", ");
         }
     } else {
-        result = m_option.translateFunction;
+        result += m_option.translateFunction + QLatin1Char('(');
-        result += QLatin1Char('(');
     }
 
     result += fixString(str, m_dindent);
 
     if (!m_option.idBased) {
-        result += QLatin1String(", ");
+        result += QLatin1String(", ") + comment;
-        result += comment;
     }
 
     result += QLatin1Char(')');

src/widgets/widgets/qspinbox.cpp

@@ -479,9 +479,8 @@ QString QSpinBox::textFromValue(int value) const
     QString str;
 
     if (d->displayIntegerBase != 10) {
-        str = QString::number(qAbs(value), d->displayIntegerBase);
+        const QLatin1String prefix = value < 0 ? QLatin1String("-") : QLatin1String();
-        if (value < 0)
+        str = prefix + QString::number(qAbs(value), d->displayIntegerBase);
-            str.prepend('-');
     } else {
         str = locale().toString(value);
         if (!d->showGroupSeparator && (qAbs(value) >= 1000 || value == INT_MIN)) {

src/widgets/widgets/qwidgettextcontrol.cpp

@@ -2641,8 +2641,8 @@ void QWidgetTextControl::insertFromMimeData(const QMimeData *source)
 #ifndef QT_NO_TEXTHTMLPARSER
     if (source->hasFormat(QLatin1String("application/x-qrichtext")) && d->acceptRichText) {
         // x-qrichtext is always UTF-8 (taken from Qt3 since we don't use it anymore).
-        QString richtext = QString::fromUtf8(source->data(QLatin1String("application/x-qrichtext")));
+        const QString richtext = QLatin1String("<meta name=\"qrichtext\" content=\"1\" />")
-        richtext.prepend(QLatin1String("<meta name=\"qrichtext\" content=\"1\" />"));
+                + QString::fromUtf8(source->data(QLatin1String("application/x-qrichtext")));
         fragment = QTextDocumentFragment::fromHtml(richtext, d->doc);
         hasData = true;
     } else if (source->hasHtml() && d->acceptRichText) {