New class QgsInterval for storing durations between datetimes

Move the QgsExpression::Interval class out to its own QgsInterval
class, extend with new methods and add tests

Add a typedef to keep API compatibility for 2.16

python/core/core.sip

@@ -57,6 +57,7 @@
 %Include qgsgml.sip
 %Include qgsgmlschema.sip
 %Include qgshistogram.sip
+%Include qgsinterval.sip
 %Include qgsjsonutils.sip
 %Include qgsmaptopixelgeometrysimplifier.sip
 %Include qgstransaction.sip

python/core/qgsexpression.sip

@@ -671,33 +671,33 @@ class QgsExpression
         virtual QString dump() const;
     };
 
+    //TODO QGIS 3.0 - remove
+    //! @deprecated use QgsInterval instead
     class Interval
-    {
+   {
       public:
         Interval( int seconds = 0 );
 
         //! interval length in years
-        double years();
+        double years() const;
         //! interval length in months
-        double months();
+        double months() const;
         //! interval length in weeks
-        double weeks();
+        double weeks() const;
         //! interval length in days
-        double days();
+        double days() const;
         //! interval length in hours
-        double hours();
+        double hours() const;
         //! interval length in minutus
-        double minutes();
+        double minutes() const;
         //! interval length in seconds
-        double seconds();
+        double seconds() const;
         //! getter interval validity
-        bool isValid();
+        bool isValid() const;
         //! setter interval validity
         void setValid( bool valid );
         //! compare two intervals
         bool operator==( QgsExpression::Interval other ) const;
-        //! return an invalid interval
-        static QgsExpression::Interval invalidInterVal();
         //! convert a string to an interval
         static QgsExpression::Interval fromString( const QString& string );
     };
@@ -749,7 +749,12 @@ class QgsExpression
         bool compare( double diff );
         int computeInt( int x, int y );
         double computeDouble( double x, double y );
-        QDateTime computeDateTimeFromInterval( const QDateTime& d, QgsExpression::Interval *i );
+
+        /** Computes the result date time calculation from a start datetime and an interval
+         * @param d start datetime
+         * @param i interval to add or subtract (depending on mOp)
+         */
+        QDateTime computeDateTimeFromInterval( const QDateTime& d, QgsInterval *i );
     };
 
     class NodeInOperator : QgsExpression::Node

python/core/qgsinterval.sip

@@ -0,0 +1,136 @@
+/** \ingroup core
+ * \class QgsInterval
+ * \brief A representation of the interval between two datetime values.
+ * \note Added in version 2.16
+ */
+
+class QgsInterval
+{
+%TypeHeaderCode
+#include <qgsinterval.h>
+%End
+
+  public:
+
+    // YEAR const value taken from postgres query
+    // SELECT EXTRACT(EPOCH FROM interval '1 year')
+    //! Seconds per year (average)
+    static const int YEARS;
+    //! Seconds per month, based on 30 day month
+    static const int MONTHS;
+    //! Seconds per week
+    static const int WEEKS;
+    //! Seconds per day
+    static const int DAY;
+    //! Seconds per hour
+    static const int HOUR;
+    //! Seconds per minute
+    static const int MINUTE;
+
+    /** Default constructor for QgsInterval. Creates an invalid interval.
+     */
+    QgsInterval();
+
+    /** Constructor for QgsInterval.
+     * @param seconds duration of interval in seconds
+     */
+    QgsInterval( double seconds );
+
+    /** Returns the interval duration in years (based on an average year length)
+     * @see setYears()
+     */
+    double years() const;
+
+    /** Sets the interval duration in years.
+     * @param years duration in years (based on average year length)
+     * @see years()
+     */
+    void setYears( double years );
+
+    /** Returns the interval duration in months (based on a 30 day month).
+     * @see setMonths()
+     */
+    double months() const;
+
+    /** Sets the interval duration in months.
+     * @param months duration in months (based on a 30 day month)
+     * @see months()
+     */
+    void setMonths( double months );
+
+    /** Returns the interval duration in weeks.
+     * @see setWeeks()
+     */
+    double weeks() const;
+
+    /** Sets the interval duration in weeks.
+     * @param weeks duration in weeks
+     * @see weeks()
+     */
+    void setWeeks( double weeks );
+
+    /** Returns the interval duration in days.
+     * @see setDays()
+     */
+    double days() const;
+
+    /** Sets the interval duration in days.
+     * @param days duration in days
+     * @see days()
+     */
+    void setDays( double days );
+
+    /** Returns the interval duration in hours.
+     * @see setHours()
+     */
+    double hours() const;
+
+    /** Sets the interval duration in hours.
+     * @param hours duration in hours
+     * @see hours()
+     */
+    void setHours( double hours );
+
+    /** Returns the interval duration in minutes.
+     * @see setMinutes()
+     */
+    double minutes() const;
+
+    /** Sets the interval duration in minutes.
+     * @param minutes duration in minutes
+     * @see minutes()
+     */
+    void setMinutes( double minutes );
+
+    /** Returns the interval duration in seconds.
+     * @see setSeconds()
+     */
+    double seconds() const;
+
+    /** Sets the interval duration in seconds.
+     * @param seconds duration in seconds
+     * @see seconds()
+     */
+    void setSeconds( double seconds );
+
+    /** Returns true if the interval is valid.
+     * @see setValid()
+     */
+    bool isValid() const;
+
+    /** Sets whether the interval is valid.
+     * @param valid set to true to set the interval as valid.
+     * @see isValid()
+     */
+    void setValid( bool valid );
+
+    bool operator==( const QgsInterval& other ) const;
+
+    /** Converts a string to an interval
+     * @param string string to parse
+     * @returns interval, or invalid interval if string could not be parsed
+     */
+    static QgsInterval fromString( const QString& string );
+
+};
+

src/core/CMakeLists.txt

@@ -121,6 +121,7 @@ SET(QGIS_CORE_SRCS
   qgsgml.cpp
   qgsgmlschema.cpp
   qgshistogram.cpp
+  qgsinterval.cpp
   qgsjsonutils.cpp
   qgslabel.cpp
   qgslabelattributes.cpp
@@ -637,6 +638,7 @@ SET(QGIS_CORE_HDRS
   qgsgeometrycache.h
   qgshistogram.h
   qgsindexedfeature.h
+  qgsinterval.h
   qgsjsonutils.h
   qgslayerdefinition.h
   qgslabel.h