Added QDateTime::msecsTo()

This adds a QDateTime::msecsTo() function which is similar to
QDateTime::secsTo().
This refers to QTBUG-8790 and task 147685. According to the task this
functionality should have been added in version 4.5.0 but it never was.

Task-number: 147685
Task-number: QTBUG-8790

Merge-request: 501
Reviewed-by: Benjamin Poulain <benjamin.poulain@nokia.com>
Reviewed-by: Andreas Kling <andreas.kling@nokia.com>

3 files changed, 63 insertions, 8 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 9afcd80..9f5d8c6 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -1705,7 +1705,7 @@ int QTime::secsTo(const QTime &t) const
     Note that the time will wrap if it passes midnight. See addSecs()
     for an example.
 
-    \sa addSecs(), msecsTo()
+    \sa addSecs(), msecsTo(), QDateTime::addMSecs()
 */
 
 QTime QTime::addMSecs(int ms) const
@@ -1734,7 +1734,7 @@ QTime QTime::addMSecs(int ms) const
     seconds in a day, the result is always between -86400000 and
     86400000 ms.
 
-    \sa secsTo(), addMSecs()
+    \sa secsTo(), addMSecs(), QDateTime::msecsTo()
 */
 
 int QTime::msecsTo(const QTime &t) const
@@ -2042,10 +2042,11 @@ int QTime::elapsed() const
     later.
 
     You can increment (or decrement) a datetime by a given number of
-    seconds using addSecs(), or days using addDays(). Similarly you can
-    use addMonths() and addYears(). The daysTo() function returns the
-    number of days between two datetimes, and secsTo() returns the
-    number of seconds between two datetimes.
+    milliseconds using addMSecs(), seconds using addSecs(), or days
+    using addDays(). Similarly you can use addMonths() and addYears().
+    The daysTo() function returns the number of days between two datetimes,
+    secsTo() returns the number of seconds between two datetimes, and
+    msecsTo() returns the number of milliseconds between two datetimes.
 
     QDateTime can store datetimes as \l{Qt::LocalTime}{local time} or
     as \l{Qt::UTC}{UTC}. QDateTime::currentDateTime() returns a
@@ -2719,7 +2720,7 @@ QDateTime QDateTime::addSecs(int s) const
     later than the datetime of this object (or earlier if \a msecs is
     negative).
 
-    \sa addSecs(), secsTo(), addDays(), addMonths(), addYears()
+    \sa addSecs(), msecsTo(), addDays(), addMonths(), addYears()
 */
 QDateTime QDateTime::addMSecs(qint64 msecs) const
 {
@@ -2731,7 +2732,7 @@ QDateTime QDateTime::addMSecs(qint64 msecs) const
     datetime. If the \a other datetime is earlier than this datetime,
     the value returned is negative.
 
-    \sa addDays(), secsTo()
+    \sa addDays(), secsTo(), msecsTo()
 */
 
 int QDateTime::daysTo(const QDateTime &other) const
@@ -2766,6 +2767,33 @@ int QDateTime::secsTo(const QDateTime &other) const
 }
 
 /*!
+    Returns the number of milliseconds from this datetime to the \a other
+    datetime. If the \a other datetime is earlier than this datetime,
+    the value returned is negative.
+
+    Before performing the comparison, the two datetimes are converted
+    to Qt::UTC to ensure that the result is correct if one of the two
+    datetimes has daylight saving time (DST) and the other doesn't.
+
+    \sa addMSecs(), daysTo(), QTime::msecsTo()
+*/
+
+qint64 QDateTime::msecsTo(const QDateTime &other) const
+{
+    QDate selfDate;
+    QDate otherDate;
+    QTime selfTime;
+    QTime otherTime;
+
+    d->getUTC(selfDate, selfTime);
+    other.d->getUTC(otherDate, otherTime);
+
+    return (static_cast<qint64>(selfDate.daysTo(otherDate)) * static_cast<qint64>(MSECS_PER_DAY))
+           + static_cast<qint64>(selfTime.msecsTo(otherTime));
+}
+
+
+/*!
     \fn QDateTime QDateTime::toTimeSpec(Qt::TimeSpec specification) const
 
     Returns a copy of this datetime configured to use the given time
diff --git a/src/corelib/tools/qdatetime.h b/src/corelib/tools/qdatetime.h
index f445f1c..2466aeb 100644
--- a/src/corelib/tools/qdatetime.h
+++ b/src/corelib/tools/qdatetime.h
@@ -251,6 +251,7 @@ public:
     inline QDateTime toUTC() const { return toTimeSpec(Qt::UTC); }
     int daysTo(const QDateTime &) const;
     int secsTo(const QDateTime &) const;
+    qint64 msecsTo(const QDateTime &) const;
 
     bool operator==(const QDateTime &other) const;
     inline bool operator!=(const QDateTime &other) const { return !(*this == other); }
diff --git a/tests/auto/qdatetime/tst_qdatetime.cpp b/tests/auto/qdatetime/tst_qdatetime.cpp
index 6aca996..47c54a5 100644
--- a/tests/auto/qdatetime/tst_qdatetime.cpp
+++ b/tests/auto/qdatetime/tst_qdatetime.cpp
@@ -106,6 +106,8 @@ private slots:
     void daysTo();
     void secsTo_data();
     void secsTo();
+    void msecsTo_data();
+    void msecsTo();
     void operator_eqeq();
     void currentDateTime();
     void currentDateTimeUtc();
@@ -910,6 +912,30 @@ void tst_QDateTime::secsTo()
     QVERIFY((dt >= result) == (0 >= nsecs));
 }
 
+void tst_QDateTime::msecsTo_data()
+{
+    addMSecs_data();
+}
+
+void tst_QDateTime::msecsTo()
+{
+    QFETCH(QDateTime, dt);
+    QFETCH(int, nsecs);
+    QFETCH(QDateTime, result);
+
+#ifdef Q_OS_IRIX
+    QEXPECT_FAIL("cet4", "IRIX databases say 1970 had DST", Abort);
+#endif
+    QCOMPARE(dt.msecsTo(result), qint64(nsecs) * 1000);
+    QCOMPARE(result.msecsTo(dt), -qint64(nsecs) * 1000);
+    QVERIFY((dt == result) == (0 == (qint64(nsecs) * 1000)));
+    QVERIFY((dt != result) == (0 != (qint64(nsecs) * 1000)));
+    QVERIFY((dt < result) == (0 < (qint64(nsecs) * 1000)));
+    QVERIFY((dt <= result) == (0 <= (qint64(nsecs) * 1000)));
+    QVERIFY((dt > result) == (0 > (qint64(nsecs) * 1000)));
+    QVERIFY((dt >= result) == (0 >= (qint64(nsecs) * 1000)));
+}
+
 void tst_QDateTime::currentDateTime()
 {
 #if defined(Q_OS_WINCE)