Implement date-time fromString(QStringView...) methods

Inline the QString versions. One const QString & variant remains in
each case: the date-time parser keeps a copy of the string it's been
given, so the methods calling it have a hybrid method taking the
string as the text to parse along with a view as the format. This
avoids copying the string when the caller has an actual QString to
pass in; the version with QStringView for both parameters has to
toString() the text to be parsed, at some point on the way into the
parser, but we can avoid that in the QString-accepting ones.

Fixes: QTBUG-86172
Change-Id: I6a4390df90945af74a5eac2f0a752febd925ad62
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 98 insertions, 23 deletions

diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index 1c84c66148..4a5437c692 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -1453,6 +1453,8 @@ ParsedInt readInt(QStringView text)
 }
 
 /*!
+    \fn QDate QDate::fromString(const QString &string, Qt::DateFormat format)
+
     Returns the QDate represented by the \a string, using the
     \a format given, or an invalid date if the string cannot be
     parsed.
@@ -1463,7 +1465,11 @@ ParsedInt readInt(QStringView text)
     \sa toString(), QLocale::toDate()
 */
 
-QDate QDate::fromString(const QString &string, Qt::DateFormat format)
+/*!
+    \overload
+    \since 6.0
+*/
+QDate QDate::fromString(QStringView string, Qt::DateFormat format)
 {
     if (string.isEmpty())
         return QDate();
@@ -1473,7 +1479,7 @@ QDate QDate::fromString(const QString &string, Qt::DateFormat format)
         return rfcDateImpl(string).date;
     default:
     case Qt::TextDate: {
-        auto parts = QStringView{string}.split(u' ', Qt::SkipEmptyParts);
+        auto parts = string.split(u' ', Qt::SkipEmptyParts);
 
         if (parts.count() != 4)
             return QDate();
@@ -1494,10 +1500,9 @@ QDate QDate::fromString(const QString &string, Qt::DateFormat format)
         // Semi-strict parsing, must be long enough and have punctuators as separators
         if (string.size() >= 10 && string.at(4).isPunct() && string.at(7).isPunct()
                 && (string.size() == 10 || !string.at(10).isDigit())) {
-            QStringView view(string);
-            const ParsedInt year = readInt(view.mid(0, 4));
-            const ParsedInt month = readInt(view.mid(5, 2));
-            const ParsedInt day = readInt(view.mid(8, 2));
+            const ParsedInt year = readInt(string.mid(0, 4));
+            const ParsedInt month = readInt(string.mid(5, 2));
+            const ParsedInt day = readInt(string.mid(8, 2));
             if (year.ok && year.value > 0 && year.value <= 9999 && month.ok && day.ok)
                 return QDate(year.value, month.value, day.value);
         }
@@ -1571,7 +1576,17 @@ QDate QDate::fromString(const QString &string, Qt::DateFormat format)
         QLocale::toDate()
 */
 
-QDate QDate::fromString(const QString &string, const QString &format, QCalendar cal)
+/*!
+    \fn QDate QDate::fromString(QStringView string, QStringView format, QCalendar cal)
+    \overload
+    \since 6.0
+*/
+
+/*!
+    \overload
+    \since 6.0
+*/
+QDate QDate::fromString(const QString &string, QStringView format, QCalendar cal)
 {
     QDate date;
 #if QT_CONFIG(datetimeparser)
@@ -2180,12 +2195,19 @@ static QTime fromIsoTimeString(QStringView string, Qt::DateFormat format, bool *
 }
 
 /*!
+    \fn QTime QTime::fromString(const QString &string, Qt::DateFormat format)
+
     Returns the time represented in the \a string as a QTime using the
     \a format given, or an invalid time if this is not possible.
 
     \sa toString(), QLocale::toTime()
 */
-QTime QTime::fromString(const QString &string, Qt::DateFormat format)
+
+/*!
+    \overload
+    \since 6.0
+*/
+QTime QTime::fromString(QStringView string, Qt::DateFormat format)
 {
     if (string.isEmpty())
         return QTime();
@@ -2197,11 +2219,13 @@ QTime QTime::fromString(const QString &string, Qt::DateFormat format)
     case Qt::ISODateWithMs:
     case Qt::TextDate:
     default:
-        return fromIsoTimeString(QStringView(string), format, nullptr);
+        return fromIsoTimeString(string, format, nullptr);
     }
 }
 
 /*!
+    \fn QTime QTime::fromString(const QString &string, const QString &format)
+
     Returns the QTime represented by the \a string, using the \a
     format given, or an invalid time if the string cannot be parsed.
 
@@ -2261,7 +2285,17 @@ QTime QTime::fromString(const QString &string, Qt::DateFormat format)
     QLocale::toTime()
 */
 
-QTime QTime::fromString(const QString &string, const QString &format)
+/*!
+    \fn QTime QTime::fromString(QStringView string, QStringView format)
+    \overload
+    \since 6.0
+*/
+
+/*!
+    \overload
+    \since 6.0
+*/
+QTime QTime::fromString(const QString &string, QStringView format)
 {
     QTime time;
 #if QT_CONFIG(datetimeparser)
@@ -2275,7 +2309,6 @@ QTime QTime::fromString(const QString &string, const QString &format)
 #endif
     return time;
 }
-
 #endif // datestring
 
 
@@ -4651,6 +4684,8 @@ QDateTime QDateTime::fromSecsSinceEpoch(qint64 secs, const QTimeZone &timeZone)
 #if QT_CONFIG(datestring) // depends on, so implies, textdate
 
 /*!
+    \fn QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
+
     Returns the QDateTime represented by the \a string, using the
     \a format given, or an invalid datetime if this is not possible.
 
@@ -4659,7 +4694,12 @@ QDateTime QDateTime::fromSecsSinceEpoch(qint64 secs, const QTimeZone &timeZone)
 
     \sa toString(), QLocale::toDateTime()
 */
-QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
+
+/*!
+    \overload
+    \since 6.0
+*/
+QDateTime QDateTime::fromString(QStringView string, Qt::DateFormat format)
 {
     if (string.isEmpty())
         return QDateTime();
@@ -4688,7 +4728,7 @@ QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
             return date.startOfDay();
 
         Qt::TimeSpec spec = Qt::LocalTime;
-        QStringView isoString = QStringView(string).mid(10); // trim "yyyy-MM-dd"
+        QStringView isoString = string.mid(10); // trim "yyyy-MM-dd"
 
         // Must be left with T (or space) and at least one digit for the hour:
         if (isoString.size() < 2
@@ -4738,7 +4778,7 @@ QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
         return QDateTime(date, time, spec, offset);
     }
     case Qt::TextDate: {
-        QList<QStringView> parts = QStringView { string }.split(u' ', Qt::SkipEmptyParts);
+        QList<QStringView> parts = string.split(u' ', Qt::SkipEmptyParts);
 
         if ((parts.count() < 5) || (parts.count() > 6))
             return QDateTime();
@@ -4850,6 +4890,8 @@ QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
 }
 
 /*!
+    \fn QDateTime QDateTime::fromString(const QString &string, const QString &format, QCalendar cal)
+
     Returns the QDateTime represented by the \a string, using the \a
     format given, or an invalid datetime if the string cannot be parsed.
 
@@ -4908,7 +4950,17 @@ QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
     QLocale::toDateTime()
 */
 
-QDateTime QDateTime::fromString(const QString &string, const QString &format, QCalendar cal)
+/*!
+    \fn QDateTime QDateTime::fromString(QStringView string, QStringView format, QCalendar cal)
+    \overload
+    \since 6.0
+*/
+
+/*!
+    \overload
+    \since 6.0
+*/
+QDateTime QDateTime::fromString(const QString &string, QStringView format, QCalendar cal)
 {
 #if QT_CONFIG(datetimeparser)
     QDateTime datetime;
diff --git a/src/corelib/time/qdatetime.h b/src/corelib/time/qdatetime.h
index 60e3529a45..91f63605f2 100644
--- a/src/corelib/time/qdatetime.h
+++ b/src/corelib/time/qdatetime.h
@@ -126,11 +126,16 @@ public:
 
     static QDate currentDate();
 #if QT_CONFIG(datestring)
-    static QDate fromString(QStringView s, Qt::DateFormat f = Qt::TextDate);
-    static QDate fromString(QStringView s, QStringView format, QCalendar cal = QCalendar());
+    static QDate fromString(QStringView string, Qt::DateFormat format = Qt::TextDate);
+    static QDate fromString(QStringView string, QStringView format, QCalendar cal = QCalendar())
+    { return fromString(string.toString(), format, cal); }
+    static QDate fromString(const QString &string, QStringView format, QCalendar cal = QCalendar());
 # if QT_STRINGVIEW_LEVEL < 2
-    static QDate fromString(const QString &s, Qt::DateFormat f = Qt::TextDate);
-    static QDate fromString(const QString &s, const QString &format, QCalendar cal = QCalendar());
+    static QDate fromString(const QString &string, Qt::DateFormat format = Qt::TextDate)
+    { return fromString(qToStringViewIgnoringNull(string), format); }
+    static QDate fromString(const QString &string, const QString &format,
+                            QCalendar cal = QCalendar())
+    { return fromString(string, qToStringViewIgnoringNull(format), cal); }
 # endif
 #endif
     static bool isValid(int y, int m, int d);
@@ -200,8 +205,16 @@ public:
 
     static QTime currentTime();
 #if QT_CONFIG(datestring)
-    static QTime fromString(const QString &s, Qt::DateFormat f = Qt::TextDate);
-    static QTime fromString(const QString &s, const QString &format);
+    static QTime fromString(QStringView string, Qt::DateFormat format = Qt::TextDate);
+    static QTime fromString(QStringView string, QStringView format)
+    { return fromString(string.toString(), format); }
+    static QTime fromString(const QString &string, QStringView format);
+# if QT_STRINGVIEW_LEVEL < 2
+    static QTime fromString(const QString &string, Qt::DateFormat format = Qt::TextDate)
+    { return fromString(qToStringViewIgnoringNull(string), format); }
+    static QTime fromString(const QString &string, const QString &format)
+    { return fromString(string, qToStringViewIgnoringNull(format)); }
+# endif
 #endif
     static bool isValid(int h, int m, int s, int ms = 0);
 
@@ -338,9 +351,19 @@ public:
     static QDateTime currentDateTime();
     static QDateTime currentDateTimeUtc();
 #if QT_CONFIG(datestring)
-    static QDateTime fromString(const QString &s, Qt::DateFormat f = Qt::TextDate);
-    static QDateTime fromString(const QString &s, const QString &format,
+    static QDateTime fromString(QStringView string, Qt::DateFormat format = Qt::TextDate);
+    static QDateTime fromString(QStringView string, QStringView format,
+                                QCalendar cal = QCalendar())
+    { return fromString(string.toString(), format, cal); }
+    static QDateTime fromString(const QString &string, QStringView format,
                                 QCalendar cal = QCalendar());
+# if QT_STRINGVIEW_LEVEL < 2
+    static QDateTime fromString(const QString &string, Qt::DateFormat format = Qt::TextDate)
+    { return fromString(qToStringViewIgnoringNull(string), format); }
+    static QDateTime fromString(const QString &string, const QString &format,
+                                QCalendar cal = QCalendar())
+    { return fromString(string, qToStringViewIgnoringNull(format), cal); }
+# endif
 #endif
 
     static QDateTime fromMSecsSinceEpoch(qint64 msecs, Qt::TimeSpec spec = Qt::LocalTime,