Methods in time struct: time-local and time-utc.

* lib.c (time_local_s, time_utc_s): New symbol variables.
(time_meth): New static function.
(time_init): Initialize new symbol variables. Create the
time struct with two static slots, and initialize those
static slots to be methods.

* txr.1: Introduce "the epoch" term. Document the
new methods.

2 files changed, 66 insertions, 5 deletions

diff --git a/lib.c b/lib.c
index 32d5b5e7..e29ff99c 100644
--- a/lib.c
+++ b/lib.c
@@ -113,7 +113,8 @@ val list_f, less_f, greater_f;
 
 val prog_string;
 
-val time_s, year_s, month_s, day_s, hour_s, min_s, sec_s, dst_s;
+val time_s, time_local_s, time_utc_s;
+val year_s, month_s, day_s, hour_s, min_s, sec_s, dst_s;
 
 static val env_list;
 
@@ -8989,9 +8990,27 @@ val make_time_utc(val year, val month, val day,
   return make_time_impl(pmktime, year, month, day, hour, minute, second, isdst);
 }
 
+static val time_meth(val utc_p, val time_struct)
+{
+  val year = slot(time_struct, year_s);
+  val month = slot(time_struct, month_s);
+  val day = slot(time_struct, day_s);
+  val hour = slot(time_struct, hour_s);
+  val min = slot(time_struct, min_s);
+  val sec = slot(time_struct, sec_s);
+  val dst = slot(time_struct, dst_s);
+
+  return (utc_p ? make_time_utc : make_time)(year, month, day,
+                                             hour, min, sec, dst);
+}
+
 static void time_init(void)
 {
+  val time_st;
+
   time_s = intern(lit("time"), user_package);
+  time_local_s = intern(lit("time-local"), user_package);
+  time_utc_s = intern(lit("time-utc"), user_package);
   year_s = intern(lit("year"), user_package);
   month_s = intern(lit("month"), user_package);
   day_s = intern(lit("day"), user_package);
@@ -9000,9 +9019,14 @@ static void time_init(void)
   sec_s = intern(lit("sec"), user_package);
   dst_s = intern(lit("dst"), user_package);
 
-  make_struct_type(time_s, nil, nil,
-                   list(year_s, month_s, day_s,
-                        hour_s, min_s, sec_s, dst_s, nao), nil, nil, nil, nil);
+  time_st = make_struct_type(time_s, nil,
+                             list(time_local_s, time_utc_s, nao),
+                             list(year_s, month_s, day_s,
+                                  hour_s, min_s, sec_s, dst_s, nao),
+                             nil, nil, nil, nil);
+
+  static_slot_set(time_st, time_local_s, func_f1(nil, time_meth));
+  static_slot_set(time_st, time_utc_s, func_f1(t, time_meth));
 }
 
 void init(const wchar_t *pn, mem_t *(*oom)(mem_t *, size_t),
diff --git a/txr.1 b/txr.1
index f5d4214d..a70d1623 100644
--- a/txr.1
+++ b/txr.1
@@ -35159,7 +35159,9 @@ pseudo-random number generator.
 The
 .code time
 function returns the number of seconds that have elapsed since
-midnight, January 1, 1970, in the UTC timezone.
+midnight, January 1, 1970, in the UTC timezone: a point in
+time called
+.IR "the epoch" .
 
 The
 .code time-usec
@@ -35302,6 +35304,41 @@ function or from the
 .code time-usec
 function.
 
+.coNP Methods @ time-local and @ time-utc
+.synb
+.mets << time-struct .(time-local)
+.mets << time-struct .(time-utc)
+.syne
+.desc
+The
+.code time
+structure has two methods called
+.code time-local
+and
+.codn time-utc .
+
+The
+.code time-local
+function considers the slots of the
+.code time
+structure instance
+.meta time-struct
+to be local time, and returns its integer representation
+as the number of seconds since the epoch.
+
+The
+.code time-utc
+function is similar, except it considers
+the slots of
+.meta time-struct
+to be in the UTC time zone.
+
+Note: these functions work by converting the slots into arguments
+which are applied to
+.code make-time
+or
+.codn make-time-utc .
+
 .coNP Functions @ make-time and @ make-time-utc
 .synb
 .mets (make-time < year < month < day < hour < minute < second << dst-advice )