QStringView/QLatin1String: add trimmed()

... using the same qt_trimmed(), qTrimmed(), Q..::trimmed() split we've
been using for all other out-of-line string-view member functions to
avoid forcing string-view objects onto the stack for the passing of 'this'.

In the test, had to fix nullness not being propagated from a QByteArray
to the QLatin1String constructed from it. Probably worth fixing in
QLatin1String(QByteArray), too.

[ChangeLog][QtCore] Added qTrimmed() free functions.

[ChangeLog][QtCore][QLatin1String] Added trimmed() function.

Change-Id: I73c18ef87e203f30f7552c10dd5c84223bcfae0e
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

5 files changed, 66 insertions, 0 deletions

diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index a6295da45e..907de3cb4b 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -5208,6 +5208,41 @@ QString QString::simplified_helper(QString &str)
     return QStringAlgorithms<QString>::simplified_helper(str);
 }
 
+namespace {
+    template <typename StringView>
+    StringView qt_trimmed(StringView s) Q_DECL_NOTHROW
+    {
+        auto begin = s.begin();
+        auto end = s.end();
+        QStringAlgorithms<const StringView>::trimmed_helper_positions(begin, end);
+        return StringView{begin, end};
+    }
+}
+
+/*!
+    \fn QStringView qTrimmed(QStringView s)
+    \fn QLatin1String qTrimmed(QLatin1String s)
+    \relates QStringView
+    \since 5.10
+
+    Returns \a s with whitespace removed from the start and the end.
+
+    Whitespace means any character for which QChar::isSpace() returns
+    \c true. This includes the ASCII characters '\\t', '\\n', '\\v',
+    '\\f', '\\r', and ' '.
+
+    \sa QString::trimmed(), QStringView::trimmed(), QLatin1String::trimmed()
+*/
+QStringView qTrimmed(QStringView s) Q_DECL_NOTHROW
+{
+    return qt_trimmed(s);
+}
+
+QLatin1String qTrimmed(QLatin1String s) Q_DECL_NOTHROW
+{
+    return qt_trimmed(s);
+}
+
 /*!
     \fn QString QString::trimmed() const
 
@@ -9127,6 +9162,19 @@ QString &QString::setRawData(const QChar *unicode, int size)
     \sa mid(), left(), right(), chopped(), truncate()
 */
 
+/*!
+    \fn QLatin1String QLatin1String::trimmed() const
+    \since 5.10
+
+    Strips leading and trailing whitespace and returns the result.
+
+    Whitespace means any character for which QChar::isSpace() returns
+    \c true. This includes the ASCII characters '\\t', '\\n', '\\v',
+    '\\f', '\\r', and ' '.
+
+    \sa qTrimmed()
+*/
+
 /*! \fn bool QLatin1String::operator==(const QString &other) const
 
     Returns \c true if this string is equal to string \a other;
diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index 33ecba6cf8..d5301a396f 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -167,6 +167,8 @@ public:
     Q_DECL_RELAXED_CONSTEXPR void truncate(int n)
     { Q_ASSERT(n >= 0); Q_ASSERT(n <= size()); m_size = n; }
 
+    Q_REQUIRED_RESULT QLatin1String trimmed() const Q_DECL_NOTHROW { return qTrimmed(*this); }
+
     inline bool operator==(const QString &s) const Q_DECL_NOTHROW;
     inline bool operator!=(const QString &s) const Q_DECL_NOTHROW;
     inline bool operator>(const QString &s) const Q_DECL_NOTHROW;
diff --git a/src/corelib/tools/qstringalgorithms.h b/src/corelib/tools/qstringalgorithms.h
index 50c48bfb91..e1b8b90428 100644
--- a/src/corelib/tools/qstringalgorithms.h
+++ b/src/corelib/tools/qstringalgorithms.h
@@ -69,6 +69,8 @@ Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION bool qEndsWith(QStringView
 Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION bool qEndsWith(QLatin1String haystack, QStringView   needle, Qt::CaseSensitivity cs = Qt::CaseSensitive) Q_DECL_NOTHROW;
 Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION bool qEndsWith(QLatin1String haystack, QLatin1String needle, Qt::CaseSensitivity cs = Qt::CaseSensitive) Q_DECL_NOTHROW;
 
+Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION QStringView   qTrimmed(QStringView   s) Q_DECL_NOTHROW;
+Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION QLatin1String qTrimmed(QLatin1String s) Q_DECL_NOTHROW;
 
 Q_REQUIRED_RESULT Q_CORE_EXPORT QByteArray qConvertToLatin1(QStringView str);
 Q_REQUIRED_RESULT Q_CORE_EXPORT QByteArray qConvertToUtf8(QStringView str);
diff --git a/src/corelib/tools/qstringview.cpp b/src/corelib/tools/qstringview.cpp
index 8d2fc996e9..8eefc6d814 100644
--- a/src/corelib/tools/qstringview.cpp
+++ b/src/corelib/tools/qstringview.cpp
@@ -665,6 +665,18 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
+    \fn QStringView QStringView::trimmed() const
+
+    Strips leading and trailing whitespace and returns the result.
+
+    Whitespace means any character for which QChar::isSpace() returns
+    \c true. This includes the ASCII characters '\\t', '\\n', '\\v',
+    '\\f', '\\r', and ' '.
+
+    \sa qTrimmed()
+*/
+
+/*!
     \fn bool QStringView::startsWith(QStringView str, Qt::CaseSensitivity cs) const
     \fn bool QStringView::startsWith(QLatin1String l1, Qt::CaseSensitivity cs) const
     \fn bool QStringView::startsWith(QChar ch) const
diff --git a/src/corelib/tools/qstringview.h b/src/corelib/tools/qstringview.h
index fdbf644518..24be441b00 100644
--- a/src/corelib/tools/qstringview.h
+++ b/src/corelib/tools/qstringview.h
@@ -245,6 +245,8 @@ public:
     Q_DECL_RELAXED_CONSTEXPR void chop(qssize_t n)
     { Q_ASSERT(n >= 0); Q_ASSERT(n <= size()); m_size -= n; }
 
+    Q_REQUIRED_RESULT QStringView trimmed() const Q_DECL_NOTHROW { return qTrimmed(*this); }
+
     Q_REQUIRED_RESULT bool startsWith(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const Q_DECL_NOTHROW
     { return qStartsWith(*this, s, cs); }
     Q_REQUIRED_RESULT inline bool startsWith(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const Q_DECL_NOTHROW;