QStringView: add isLower and isUpper

[ChangeLog][QtCore][QStringView] Added isLower() and isUpper()

Change-Id: Ie6cd20bd375d42cbdfb17953b2307d025c31ec77
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

5 files changed, 59 insertions, 18 deletions

diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 93e541e712..dd02fa79fe 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -5416,6 +5416,27 @@ bool QString::endsWith(QChar c, Qt::CaseSensitivity cs) const
     return foldCase(at(size() - 1)) == foldCase(c);
 }
 
+static bool checkCase(QStringView s, QUnicodeTables::Case c) noexcept
+{
+    QStringIterator it(s);
+    while (it.hasNext()) {
+        const char32_t uc = it.next();
+        if (qGetProp(uc)->cases[c].diff)
+            return false;
+    }
+    return true;
+}
+
+bool QtPrivate::isLower(QStringView s) noexcept
+{
+    return checkCase(s, QUnicodeTables::LowerCase);
+}
+
+bool QtPrivate::isUpper(QStringView s) noexcept
+{
+    return checkCase(s, QUnicodeTables::UpperCase);
+}
+
 /*!
     Returns \c true if the string is uppercase, that is, it's identical
     to its toUpper() folding.
@@ -5431,15 +5452,7 @@ bool QString::endsWith(QChar c, Qt::CaseSensitivity cs) const
 */
 bool QString::isUpper() const
 {
-    QStringIterator it(*this);
-
-    while (it.hasNext()) {
-        const char32_t uc = it.next();
-        if (qGetProp(uc)->cases[QUnicodeTables::UpperCase].diff)
-            return false;
-    }
-
-    return true;
+    return QtPrivate::isUpper(qToStringViewIgnoringNull(*this));
 }
 
 /*!
@@ -5457,15 +5470,7 @@ bool QString::isUpper() const
  */
 bool QString::isLower() const
 {
-    QStringIterator it(*this);
-
-    while (it.hasNext()) {
-        const char32_t uc = it.next();
-        if (qGetProp(uc)->cases[QUnicodeTables::LowerCase].diff)
-            return false;
-    }
-
-    return true;
+    return QtPrivate::isLower(qToStringViewIgnoringNull(*this));
 }
 
 static QByteArray qt_convert_to_latin1(QStringView string);
diff --git a/src/corelib/text/qstringalgorithms.h b/src/corelib/text/qstringalgorithms.h
index a8d43b3ed0..1f145ae096 100644
--- a/src/corelib/text/qstringalgorithms.h
+++ b/src/corelib/text/qstringalgorithms.h
@@ -65,6 +65,9 @@ namespace QtPrivate {
 [[nodiscard]] Q_CORE_EXPORT Q_DECL_PURE_FUNCTION QStringView   trimmed(QStringView   s) noexcept;
 [[nodiscard]] Q_CORE_EXPORT Q_DECL_PURE_FUNCTION QLatin1StringView trimmed(QLatin1StringView s) noexcept;
 
+[[nodiscard]] Q_CORE_EXPORT Q_DECL_PURE_FUNCTION bool isLower(QStringView s) noexcept;
+[[nodiscard]] Q_CORE_EXPORT Q_DECL_PURE_FUNCTION bool isUpper(QStringView s) noexcept;
+
 [[nodiscard]] Q_CORE_EXPORT Q_DECL_PURE_FUNCTION qsizetype count(QStringView haystack, QChar needle, Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept;
 [[nodiscard]] Q_CORE_EXPORT Q_DECL_PURE_FUNCTION qsizetype count(QStringView haystack, QStringView needle, Qt::CaseSensitivity cs = Qt::CaseSensitive) noexcept;
 [[nodiscard]] Q_CORE_EXPORT Q_DECL_PURE_FUNCTION qsizetype count(QStringView haystack, QLatin1StringView needle, Qt::CaseSensitivity cs = Qt::CaseSensitive);
diff --git a/src/corelib/text/qstringview.cpp b/src/corelib/text/qstringview.cpp
index 6f26a04d34..0debfbf427 100644
--- a/src/corelib/text/qstringview.cpp
+++ b/src/corelib/text/qstringview.cpp
@@ -1094,6 +1094,32 @@ or the character \a ch
 */
 
 /*!
+    \fn bool QStringView::isLower() const
+    \since 6.7
+    Returns \c true if this view is identical to its lowercase folding.
+
+    Note that this does \e not mean that the string view does not contain
+    uppercase letters (some uppercase letters do not have a lowercase
+    folding; they are left unchanged by toString().toLower()).
+    For more information, refer to the Unicode standard, section 3.13.
+
+    \sa QChar::toLower(), isUpper()
+*/
+
+/*!
+    \fn bool QStringView::isUpper() const
+    \since 6.7
+    Returns \c true if this view is identical to its uppercase folding.
+
+    Note that this does \e not mean that the the string view does not contain
+    lowercase letters (some lowercase letters do not have a uppercase
+    folding; they are left unchanged by toString().toUpper()).
+    For more information, refer to the Unicode standard, section 3.13.
+
+    \sa QChar::toUpper(), isLower()
+*/
+
+/*!
     \fn QStringView::toWCharArray(wchar_t *array) const
     \since 5.14
 
diff --git a/src/corelib/text/qstringview.h b/src/corelib/text/qstringview.h
index d62dd71bdf..e27f90c167 100644
--- a/src/corelib/text/qstringview.h
+++ b/src/corelib/text/qstringview.h
@@ -324,6 +324,11 @@ public:
     [[nodiscard]] bool isValidUtf16() const noexcept
     { return QtPrivate::isValidUtf16(*this); }
 
+    [[nodiscard]] bool isUpper() const noexcept
+    { return QtPrivate::isUpper(*this); }
+    [[nodiscard]] bool isLower() const noexcept
+    { return QtPrivate::isLower(*this); }
+
     [[nodiscard]] inline short toShort(bool *ok = nullptr, int base = 10) const;
     [[nodiscard]] inline ushort toUShort(bool *ok = nullptr, int base = 10) const;
     [[nodiscard]] inline int toInt(bool *ok = nullptr, int base = 10) const;
diff --git a/tests/auto/corelib/text/qstring/tst_qstring.cpp b/tests/auto/corelib/text/qstring/tst_qstring.cpp
index 94b84ffc4b..92b4a26640 100644
--- a/tests/auto/corelib/text/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/text/qstring/tst_qstring.cpp
@@ -2944,10 +2944,12 @@ void tst_QString::isLower_isUpper()
     QFETCH(bool, isUpper);
 
     QCOMPARE(string.isLower(), isLower);
+    QCOMPARE(QStringView(string).isLower(), isLower);
     QCOMPARE(string.toLower() == string, isLower);
     QVERIFY(string.toLower().isLower());
 
     QCOMPARE(string.isUpper(), isUpper);
+    QCOMPARE(QStringView(string).isUpper(), isUpper);
     QCOMPARE(string.toUpper() == string, isUpper);
     QVERIFY(string.toUpper().isUpper());
 }