Implement DATESUM, DATEDIFF functions.

[pspp-builds.git] / src / language / expressions / helpers.h

diff --git a/src/language/expressions/helpers.h b/src/language/expressions/helpers.h
index 0f44b35ff80b367fff44c3732930dd4cc5e786cb..b8fadc9d245daee3353660d15ec633751f929549 100644 (file)
--- a/src/language/expressions/helpers.h
+++ b/src/language/expressions/helpers.h
@@ -13,11 +13,13 @@
 #include <data/calendar.h>
 #include <data/case.h>
 #include <data/data-in.h>
+#include <data/data-out.h>
 #include <data/dictionary.h>
 #include <data/procedure.h>
 #include <data/settings.h>
 #include <data/value.h>
 #include <data/variable.h>
+#include <data/vector.h>
 #include <gsl-extras/gsl-extras.h>
 #include <language/expressions/public.h>
 #include <libpspp/compiler.h>
@@ -43,6 +45,7 @@ static inline double check_errno (double x)
 #define H_MIN 60.                       /* Minutes per hour. */
 #define MIN_S 60.                       /* Seconds per minute. */
 #define WEEK_DAY 7.                     /* Days per week. */
+#define WEEK_S (WEEK_DAY * DAY_S)       /* Seconds per week. */
 
 extern const struct substring empty_string;
 
@@ -53,6 +56,10 @@ double expr_ymd_to_ofs (double year, double month, double day);
 double expr_wkyr_to_date (double wk, double yr);
 double expr_yrday_to_date (double yr, double day);
 double expr_yrmoda (double year, double month, double day);
+double expr_date_difference (double date1, double date2,
+                             struct substring unit);
+double expr_date_sum (double date, double quantity, struct substring unit_name,
+                      struct substring method_name);
 
 struct substring alloc_string (struct expression *, size_t length);
 struct substring copy_string (struct expression *,