added operator==() and !=() for wxDateSpan

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@18515 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/datetime.h

@@ -1178,6 +1178,12 @@ private:
 // Beware about weeks: if you specify both weeks and days, the total number of
 // days added will be 7*weeks + days! See also GetTotalDays() function.
 //
+// Equality operators are defined for wxDateSpans. Two datespans are equal if
+// they both give the same target date when added to *every* source date.
+// Thus wxDateSpan::Months(1) is not equal to wxDateSpan::Days(30), because
+// they not give the same date when added to 1 Feb. But wxDateSpan::Days(14) is
+// equal to wxDateSpan::Weeks(2)
+//
 // Finally, notice that for adding hours, minutes &c you don't need this
 // class: wxTimeSpan will do the job because there are no subtleties
 // associated with those.
@@ -1524,6 +1530,24 @@ inline bool WXDLLEXPORT operator!=(const wxTimeSpan &t1, const wxTimeSpan &t2)
 // wxDateSpan
 // ----------------------------------------------------------------------------
 
+// comparison
+// ----------
+
+// ds1 == d2 if and only if for every wxDateTime t t + ds1 == t + ds2
+inline WXDLLEXPORT bool operator==(const wxDateSpan& ds1,
+                                   const wxDateSpan& ds2)
+{
+    return ds1.GetYears() == ds2.GetYears() &&
+           ds1.GetMonths() == ds2.GetMonths() &&
+           ds1.GetTotalDays() == ds2.GetTotalDays();
+}
+
+inline WXDLLEXPORT bool operator!=(const wxDateSpan& ds1,
+                                   const wxDateSpan& ds2)
+{
+  return !(ds1 == ds2);
+}
+
 // arithmetics
 // -----------