Add [time] to interpolate dates and times using strftime().

Cytoplasm/tools/tp.c

@@ -24,6 +24,7 @@
 #include <stdlib.h>
 #include <ctype.h>
 #include <string.h>
+#include <time.h>
 
 #include <Args.h>
 #include <Memory.h>
@@ -47,6 +48,18 @@ static char runtime[] =
 "[def (); str; [(][str][)]]"
 "[def #;;]"
 "[def //;;]"
+"[def day;; [time %d]]"
+"[def month;; [time %m]]"
+"[def year;; [time %Y]]"
+"[def day-name;; [time %A]]"
+"[def month-name;; [time %B]]"
+"[def hour;; [time %I]]"
+"[def minute;; [time %M]]"
+"[def second;; [time %S]]"
+"[def am/pm;; [time %p]]"
+"[def timezone;; [time %Z]]"
+"[def date;; [day-name], [month-name] [day], [year]]"
+"[def timestamp;; [hour]:[minute]:[second] [am/pm] [timezone]]"
 ;
 
 static Stream *err;
@@ -294,6 +307,26 @@ EvalExpr(char *expr, Array * stack)
 
         res = StrDuplicate(val);
     }
+    else if (StrEquals(op, "time"))
+    {
+        char *fmt = Eval(&argv, stack);
+
+        time_t currentTime = time(NULL);
+        struct tm *timeInfo = localtime(&currentTime);
+        char *timestamp = Malloc(128 * sizeof(char));
+
+        if (strftime(timestamp, 128 * sizeof(char), fmt, timeInfo))
+        {
+            res = timestamp;
+        }
+        else
+        {
+            res = StrDuplicate("");
+            Free(timestamp);
+        }
+
+        Free(fmt);
+    }
     else if (StrEquals(op, "eval"))
     {
         char *expr = Eval(&argv, stack);