QString: Add functions isUpper and isLower

[ChangeLog][QtCore][QString] Added the functions QString::isUpper
and QString::isLower to check if a string contains only uppercase
or only lowercase letters.

Change-Id: I12d3a47d4605eb4514842071e80a9ba0723d4e01
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qstring.cpp

@@ -4896,6 +4896,50 @@ bool QString::endsWith(QChar c, Qt::CaseSensitivity cs) const
     return qt_ends_with(*this, c, cs);
 }
 
+/*!
+    Returns \c true if the string only contains uppercase letters,
+    otherwise returns \c false.
+    \since 5.12
+
+    \sa QChar::isUpper(), isLower()
+*/
+bool QString::isUpper() const
+{
+    if (isEmpty())
+        return false;
+
+    const QChar *d = data();
+
+    for (int i = 0, max = size(); i < max; ++i) {
+        if (!d[i].isUpper())
+            return false;
+    }
+
+    return true;
+}
+
+/*!
+    Returns \c true if the string only contains lowercase letters,
+    otherwise returns \c false.
+    \since 5.12
+
+    \sa QChar::isLower(), isUpper()
+ */
+bool QString::isLower() const
+{
+    if (isEmpty())
+        return false;
+
+    const QChar *d = data();
+
+    for (int i = 0, max = size(); i < max; ++i) {
+        if (!d[i].isLower())
+            return false;
+    }
+
+    return true;
+}
+
 static QByteArray qt_convert_to_latin1(QStringView string);
 
 QByteArray QString::toLatin1_helper(const QString &string)

src/corelib/tools/qstring.h

@@ -409,6 +409,9 @@ public:
     bool endsWith(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
     bool endsWith(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
 
+    bool isUpper() const;
+    bool isLower() const;
+
     Q_REQUIRED_RESULT QString leftJustified(int width, QChar fill = QLatin1Char(' '), bool trunc = false) const;
     Q_REQUIRED_RESULT QString rightJustified(int width, QChar fill = QLatin1Char(' '), bool trunc = false) const;
 

tests/auto/corelib/tools/qstring/tst_qstring.cpp

@@ -452,6 +452,8 @@ private slots:
     void trimmed();
     void toUpper();
     void toLower();
+    void isUpper();
+    void isLower();
     void toCaseFolded();
     void rightJustified();
     void leftJustified();
@@ -2316,6 +2318,46 @@ void tst_QString::toLower()
 #endif
 }
 
+void tst_QString::isUpper()
+{
+    QVERIFY(!QString().isUpper());
+    QVERIFY(!QString("").isUpper());
+    QVERIFY(QString("TEXT").isUpper());
+    QVERIFY(!QString("text").isUpper());
+    QVERIFY(!QString("Text").isUpper());
+    QVERIFY(!QString("tExt").isUpper());
+    QVERIFY(!QString("teXt").isUpper());
+    QVERIFY(!QString("texT").isUpper());
+    QVERIFY(!QString("TExt").isUpper());
+    QVERIFY(!QString("teXT").isUpper());
+    QVERIFY(!QString("tEXt").isUpper());
+    QVERIFY(!QString("tExT").isUpper());
+    QVERIFY(!QString("@ABYZ[").isUpper());
+    QVERIFY(!QString("@abyz[").isUpper());
+    QVERIFY(!QString("`ABYZ{").isUpper());
+    QVERIFY(!QString("`abyz{").isUpper());
+}
+
+void tst_QString::isLower()
+{
+    QVERIFY(!QString().isLower());
+    QVERIFY(!QString("").isLower());
+    QVERIFY(QString("text").isLower());
+    QVERIFY(!QString("Text").isLower());
+    QVERIFY(!QString("tExt").isLower());
+    QVERIFY(!QString("teXt").isLower());
+    QVERIFY(!QString("texT").isLower());
+    QVERIFY(!QString("TExt").isLower());
+    QVERIFY(!QString("teXT").isLower());
+    QVERIFY(!QString("tEXt").isLower());
+    QVERIFY(!QString("tExT").isLower());
+    QVERIFY(!QString("TEXT").isLower());
+    QVERIFY(!QString("@ABYZ[").isLower());
+    QVERIFY(!QString("@abyz[").isLower());
+    QVERIFY(!QString("`ABYZ{").isLower());
+    QVERIFY(!QString("`abyz{").isLower());
+}
+
 void tst_QString::toCaseFolded()
 {
     QCOMPARE( QString().toCaseFolded(), QString() );