QString: add QStringView/QLatin1String overload of (non-multi) arg()

Use the new overload directly in QXmlStream*.

Saves 129B in QtCore text size on optimized GCC 6.1 Linux AMD64
builds, even though we added two more functions.

[ChangeLog][QtCore][QString] Added arg(QStringView),
arg(QLatin1String) overloads.

Change-Id: Idf7236dcab763824593f34182e4e0b16b5ed4321
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

5 files changed, 109 insertions, 22 deletions

diff --git a/src/corelib/doc/snippets/qstring/main.cpp b/src/corelib/doc/snippets/qstring/main.cpp
index dd65fad4e3..3a6f6483fb 100644
--- a/src/corelib/doc/snippets/qstring/main.cpp
+++ b/src/corelib/doc/snippets/qstring/main.cpp
@@ -262,6 +262,17 @@ void Widget::argFunction()
                     .arg(i).arg(total).arg(fileName);
     //! [11]
 
+    {
+    //! [11]
+    int i;                // current file's number
+    int total;            // number of files to process
+    QStringView fileName; // current file's name
+
+    QString status = QString("Processing file %1 of %2: %3")
+                    .arg(i).arg(total).arg(fileName);
+    //! [11]
+    }
+
     //! [12] //! [13]
     QString str;
     //! [12]
diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index 6c97e2563c..672dda804f 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -7363,10 +7363,10 @@ struct ArgEscapeData
     int escape_len;            // total length of escape sequences which will be replaced
 };
 
-static ArgEscapeData findArgEscapes(const QString &s)
+static ArgEscapeData findArgEscapes(QStringView s)
 {
-    const QChar *uc_begin = s.unicode();
-    const QChar *uc_end = uc_begin + s.length();
+    const QChar *uc_begin = s.begin();
+    const QChar *uc_end = s.end();
 
     ArgEscapeData d;
 
@@ -7425,11 +7425,11 @@ static ArgEscapeData findArgEscapes(const QString &s)
     return d;
 }
 
-static QString replaceArgEscapes(const QString &s, const ArgEscapeData &d, int field_width,
-                                 const QString &arg, const QString &larg, QChar fillChar = QLatin1Char(' '))
+static QString replaceArgEscapes(QStringView s, const ArgEscapeData &d, int field_width,
+                                 QStringView arg, QStringView larg, QChar fillChar)
 {
-    const QChar *uc_begin = s.unicode();
-    const QChar *uc_end = uc_begin + s.length();
+    const QChar *uc_begin = s.begin();
+    const QChar *uc_end = s.end();
 
     int abs_field_width = qAbs(field_width);
     int result_len = s.length()
@@ -7493,11 +7493,11 @@ static QString replaceArgEscapes(const QString &s, const ArgEscapeData &d, int f
             }
 
             if (locale_arg) {
-                memcpy(rc, larg.unicode(), larg.length()*sizeof(QChar));
+                memcpy(rc, larg.data(), larg.length()*sizeof(QChar));
                 rc += larg.length();
             }
             else {
-                memcpy(rc, arg.unicode(), arg.length()*sizeof(QChar));
+                memcpy(rc, arg.data(), arg.length()*sizeof(QChar));
                 rc += arg.length();
             }
 
@@ -7519,6 +7519,7 @@ static QString replaceArgEscapes(const QString &s, const ArgEscapeData &d, int f
     return result;
 }
 
+#if QT_STRINGVIEW_LEVEL < 2
 /*!
   Returns a copy of this string with the lowest numbered place marker
   replaced by string \a a, i.e., \c %1, \c %2, ..., \c %99.
@@ -7550,17 +7551,86 @@ static QString replaceArgEscapes(const QString &s, const ArgEscapeData &d, int f
 */
 QString QString::arg(const QString &a, int fieldWidth, QChar fillChar) const
 {
+    return arg(QStringView(a), fieldWidth, fillChar);
+}
+#endif // QT_STRINGVIEW_LEVEL < 2
+
+/*!
+    \overload
+    \since 5.10
+
+    Returns a copy of this string with the lowest-numbered place-marker
+    replaced by string \a a, i.e., \c %1, \c %2, ..., \c %99.
+
+    \a fieldWidth specifies the minimum amount of space that \a a
+    shall occupy. If \a a requires less space than \a fieldWidth, it
+    is padded to \a fieldWidth with character \a fillChar.  A positive
+    \a fieldWidth produces right-aligned text. A negative \a fieldWidth
+    produces left-aligned text.
+
+    This example shows how we might create a \c status string for
+    reporting progress while processing a list of files:
+
+    \snippet qstring/main.cpp 11-qstringview
+
+    First, \c arg(i) replaces \c %1. Then \c arg(total) replaces \c
+    %2. Finally, \c arg(fileName) replaces \c %3.
+
+    One advantage of using arg() over asprintf() is that the order of the
+    numbered place markers can change, if the application's strings are
+    translated into other languages, but each arg() will still replace
+    the lowest-numbered unreplaced place-marker, no matter where it
+    appears. Also, if place-marker \c %i appears more than once in the
+    string, arg() replaces all of them.
+
+    If there is no unreplaced place-marker remaining, a warning message
+    is printed and the result is undefined. Place-marker numbers must be
+    in the range 1 to 99.
+*/
+QString QString::arg(QStringView a, int fieldWidth, QChar fillChar) const
+{
     ArgEscapeData d = findArgEscapes(*this);
 
-    if (d.occurrences == 0) {
-        qWarning("QString::arg: Argument missing: %s, %s", toLocal8Bit().data(),
-                  a.toLocal8Bit().data());
+    if (Q_UNLIKELY(d.occurrences == 0)) {
+        qWarning("QString::arg: Argument missing: %ls, %ls", qUtf16Printable(*this),
+                  qUtf16Printable(a.toString()));
         return *this;
     }
     return replaceArgEscapes(*this, d, fieldWidth, a, a, fillChar);
 }
 
 /*!
+    \overload
+    \since 5.10
+
+    Returns a copy of this string with the lowest-numbered place-marker
+    replaced by string \a a, i.e., \c %1, \c %2, ..., \c %99.
+
+    \a fieldWidth specifies the minimum amount of space that \a a
+    shall occupy. If \a a requires less space than \a fieldWidth, it
+    is padded to \a fieldWidth with character \a fillChar.  A positive
+    \a fieldWidth produces right-aligned text. A negative \a fieldWidth
+    produces left-aligned text.
+
+    One advantage of using arg() over asprintf() is that the order of the
+    numbered place markers can change, if the application's strings are
+    translated into other languages, but each arg() will still replace
+    the lowest-numbered unreplaced place-marker, no matter where it
+    appears. Also, if place-marker \c %i appears more than once in the
+    string, arg() replaces all of them.
+
+    If there is no unreplaced place-marker remaining, a warning message
+    is printed and the result is undefined. Place-marker numbers must be
+    in the range 1 to 99.
+*/
+QString QString::arg(QLatin1String a, int fieldWidth, QChar fillChar) const
+{
+    QVarLengthArray<ushort> utf16(a.size());
+    qt_from_latin1(utf16.data(), a.data(), a.size());
+    return arg(QStringView(utf16.data(), utf16.size()), fieldWidth, fillChar);
+}
+
+/*!
   \fn QString QString::arg(const QString& a1, const QString& a2) const
   \overload arg()
 
diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index 5110487889..87e88d74bd 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -319,8 +319,14 @@ public:
                 QChar fillChar = QLatin1Char(' ')) const Q_REQUIRED_RESULT;
     QString arg(QChar a, int fieldWidth = 0,
                 QChar fillChar = QLatin1Char(' ')) const Q_REQUIRED_RESULT;
+#if QT_STRINGVIEW_LEVEL < 2
     QString arg(const QString &a, int fieldWidth = 0,
                 QChar fillChar = QLatin1Char(' ')) const Q_REQUIRED_RESULT;
+#endif
+    QString arg(QStringView a, int fieldWidth = 0,
+                QChar fillChar = QLatin1Char(' ')) const Q_REQUIRED_RESULT;
+    QString arg(QLatin1String a, int fieldWidth = 0,
+                QChar fillChar = QLatin1Char(' ')) const Q_REQUIRED_RESULT;
     QString arg(const QString &a1, const QString &a2) const Q_REQUIRED_RESULT;
     QString arg(const QString &a1, const QString &a2, const QString &a3) const Q_REQUIRED_RESULT;
     QString arg(const QString &a1, const QString &a2, const QString &a3,
diff --git a/src/corelib/xml/qxmlstream.cpp b/src/corelib/xml/qxmlstream.cpp
index af35193b13..ecca5569f8 100644
--- a/src/corelib/xml/qxmlstream.cpp
+++ b/src/corelib/xml/qxmlstream.cpp
@@ -1558,7 +1558,7 @@ QStringRef QXmlStreamReaderPrivate::namespaceForPrefix(const QStringRef &prefix)
 
 #if 1
      if (namespaceProcessing && !prefix.isEmpty())
-         raiseWellFormedError(QXmlStream::tr("Namespace prefix '%1' not declared").arg(prefix.toString()));
+         raiseWellFormedError(QXmlStream::tr("Namespace prefix '%1' not declared").arg(prefix));
 #endif
 
      return QStringRef();
@@ -1636,7 +1636,7 @@ void QXmlStreamReaderPrivate::resolveTag()
             if (attributes[j].name() == attribute.name()
                 && attributes[j].namespaceUri() == attribute.namespaceUri()
                 && (namespaceProcessing || attributes[j].qualifiedName() == attribute.qualifiedName()))
-                raiseWellFormedError(QXmlStream::tr("Attribute '%1' redefined.").arg(attribute.qualifiedName().toString()));
+                raiseWellFormedError(QXmlStream::tr("Attribute '%1' redefined.").arg(attribute.qualifiedName()));
         }
     }
 
@@ -1804,14 +1804,14 @@ void QXmlStreamReaderPrivate::startDocument()
             if(hasStandalone)
                 err = QXmlStream::tr("The standalone pseudo attribute must appear after the encoding.");
             if(!QXmlUtils::isEncName(name))
-                err = QXmlStream::tr("%1 is an invalid encoding name.").arg(name);
+                err = QXmlStream::tr("%1 is an invalid encoding name.").arg(value);
             else {
 #ifdef QT_NO_TEXTCODEC
                 readBuffer = QString::fromLatin1(rawReadBuffer.data(), nbytesread);
 #else
                 QTextCodec *const newCodec = QTextCodec::codecForName(name.toLatin1());
                 if (!newCodec)
-                    err = QXmlStream::tr("Encoding %1 is unsupported").arg(name);
+                    err = QXmlStream::tr("Encoding %1 is unsupported").arg(value);
                 else if (newCodec != codec && !lockEncoding) {
                     codec = newCodec;
                     delete decoder;
diff --git a/tests/auto/corelib/tools/qstring/tst_qstring.cpp b/tests/auto/corelib/tools/qstring/tst_qstring.cpp
index 3f118d04ce..4a82d952ab 100644
--- a/tests/auto/corelib/tools/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/tools/qstring/tst_qstring.cpp
@@ -4726,8 +4726,8 @@ void tst_QString::arg()
     QString s14( "%1%2%3" );
 
     QCOMPARE( s4.arg("foo"), QLatin1String("[foo]") );
-    QCOMPARE( s5.arg("foo"), QLatin1String("[foo]") );
-    QCOMPARE( s6.arg("foo"), QLatin1String("[foo]") );
+    QCOMPARE( s5.arg(QLatin1String("foo")), QLatin1String("[foo]") );
+    QCOMPARE( s6.arg(QStringViewLiteral("foo")), QLatin1String("[foo]") );
     QCOMPARE( s7.arg("foo"), QLatin1String("[foo]") );
     QCOMPARE( s8.arg("foo"), QLatin1String("[foo %1]") );
     QCOMPARE( s8.arg("foo").arg("bar"), QLatin1String("[foo bar]") );
@@ -4788,11 +4788,11 @@ void tst_QString::arg()
     QCOMPARE( QString("%%%1%%%2").arg("foo").arg("bar"), QLatin1String("%%foo%%bar") );
 
     QCOMPARE( QString("%1").arg("hello", -10), QLatin1String("hello     ") );
-    QCOMPARE( QString("%1").arg("hello", -5), QLatin1String("hello") );
-    QCOMPARE( QString("%1").arg("hello", -2), QLatin1String("hello") );
+    QCOMPARE( QString("%1").arg(QLatin1String("hello"), -5), QLatin1String("hello") );
+    QCOMPARE( QString("%1").arg(QStringViewLiteral("hello"), -2), QLatin1String("hello") );
     QCOMPARE( QString("%1").arg("hello", 0), QLatin1String("hello") );
-    QCOMPARE( QString("%1").arg("hello", 2), QLatin1String("hello") );
-    QCOMPARE( QString("%1").arg("hello", 5), QLatin1String("hello") );
+    QCOMPARE( QString("%1").arg(QLatin1String("hello"), 2), QLatin1String("hello") );
+    QCOMPARE( QString("%1").arg(QStringViewLiteral("hello"), 5), QLatin1String("hello") );
     QCOMPARE( QString("%1").arg("hello", 10), QLatin1String("     hello") );
     QCOMPARE( QString("%1%1").arg("hello"), QLatin1String("hellohello") );
     QCOMPARE( QString("%2%1").arg("hello"), QLatin1String("%2hello") );