Better support for TZ locations in the times module (#397)

* Handle panics by deferring recover as an error

* Check for type in recover handler

* Added support for times.in_location

* Added support for location (TZ) to times.date

* Updated documentation

Author: ganehag

docs/stdlib-times.md

@@ -62,9 +62,10 @@ times := import("times")
   duration.
 - `month_string(month int) => string`:  returns the English name of the month
   ("January", "February", ...).
-- `date(year int, month int, day int, hour int, min int, sec int, nsec int) => time`:
-  returns the Time corresponding to "yyyy-mm-dd hh:mm:ss + nsec nanoseconds".
-  Current location is used.
+- `date(year int, month int, day int, hour int, min int, sec int, nsec int, loc string) => time`:
+  returns the Time corresponding to "yyyy-mm-dd hh:mm:ss + nsec nanoseconds" in
+  the appropriate zone for that Time in the given (optional) location.
+  The Local time zone will be used if executed without specifying a location.
 - `now() => time`: returns the current local time.
 - `parse(format string, s string) => time`: parses a formatted string and
   returns the time value it represents. The layout defines the format by
@@ -116,5 +117,8 @@ times := import("times")
   string "2006-01-02 15:04:05.999999999 -0700 MST".
 - `is_zero(t time) => bool`: reports whether t represents the zero time
   instant, January 1, year 1, 00:00:00 UTC.
+- `in_location(t time, l string) => time`:  returns a copy of t representing
+  the same time instant, but with the copy's location information set to l for 
+  display purposes.
 - `to_local(t time) => time`: returns t with the location set to local time.
 - `to_utc(t time) => time`: returns t with the location set to UTC.

stdlib/times.go

@@ -180,6 +180,10 @@ var timesModule = map[string]tengo.Object{
 		Name:  "to_utc",
 		Value: timesToUTC,
 	}, // to_utc(time) => time
+	"in_location": &tengo.UserFunction{
+		Name:  "in_location",
+		Value: timesInLocation,
+	}, // in_location(time, location) => time
 }
 
 func timesSleep(args ...tengo.Object) (ret tengo.Object, err error) {
@@ -430,7 +434,7 @@ func timesDate(args ...tengo.Object) (
 	ret tengo.Object,
 	err error,
 ) {
-	if len(args) != 7 {
+	if len(args) < 7 || len(args) > 8 {
 		err = tengo.ErrWrongNumArguments
 		return
 	}
@@ -499,9 +503,29 @@ func timesDate(args ...tengo.Object) (
 		return
 	}
 
+	var loc *time.Location
+	if len(args) == 8 {
+		i8, ok := tengo.ToString(args[7])
+		if !ok {
+			err = tengo.ErrInvalidArgumentType{
+				Name:     "eighth",
+				Expected: "string(compatible)",
+				Found:    args[7].TypeName(),
+			}
+			return
+		}
+		loc, err = time.LoadLocation(i8)
+		if err != nil {
+			ret = wrapError(err)
+			return
+		}
+	} else {
+		loc = time.Now().Location()
+	}
+
 	ret = &tengo.Time{
 		Value: time.Date(i1,
-			time.Month(i2), i3, i4, i5, i6, i7, time.Now().Location()),
+			time.Month(i2), i3, i4, i5, i6, i7, loc),
 	}
 
 	return
@@ -1113,6 +1137,46 @@ func timesTimeLocation(args ...tengo.Object) (
 	return
 }
 
+func timesInLocation(args ...tengo.Object) (
+	ret tengo.Object,
+	err error,
+) {
+	if len(args) != 2 {
+		err = tengo.ErrWrongNumArguments
+		return
+	}
+
+	t1, ok := tengo.ToTime(args[0])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "first",
+			Expected: "time(compatible)",
+			Found:    args[0].TypeName(),
+		}
+		return
+	}
+
+	s2, ok := tengo.ToString(args[1])
+	if !ok {
+		err = tengo.ErrInvalidArgumentType{
+			Name:     "second",
+			Expected: "string(compatible)",
+			Found:    args[1].TypeName(),
+		}
+		return
+	}
+
+	location, err := time.LoadLocation(s2)
+	if err != nil {
+		ret = wrapError(err)
+		return
+	}
+
+	ret = &tengo.Time{Value: t1.In(location)}
+
+	return
+}
+
 func timesTimeString(args ...tengo.Object) (ret tengo.Object, err error) {
 	if len(args) != 1 {
 		err = tengo.ErrWrongNumArguments

stdlib/times_test.go

@@ -11,6 +11,8 @@ import (
 func TestTimes(t *testing.T) {
 	time1 := time.Date(1982, 9, 28, 19, 21, 44, 999, time.Now().Location())
 	time2 := time.Now()
+	location, _ := time.LoadLocation("Pacific/Auckland")
+	time3 := time.Date(1982, 9, 28, 19, 21, 44, 999, location)
 
 	module(t, "times").call("sleep", 1).expect(tengo.UndefinedValue)
 
@@ -35,6 +37,9 @@ func TestTimes(t *testing.T) {
 
 	module(t, "times").call("date", 1982, 9, 28, 19, 21, 44, 999).
 		expect(time1)
+	module(t, "times").call("date", 1982, 9, 28, 19, 21, 44, 999, "Pacific/Auckland").
+		expect(time3)
+
 	nowD := time.Until(module(t, "times").call("now").
 		o.(*tengo.Time).Value).Nanoseconds()
 	require.True(t, 0 > nowD && nowD > -100000000) // within 100ms
@@ -80,4 +85,5 @@ func TestTimes(t *testing.T) {
 	module(t, "times").call("time_location", time1).
 		expect(time1.Location().String())
 	module(t, "times").call("time_string", time1).expect(time1.String())
+	module(t, "times").call("in_location", time1, location.String()).expect(time1.In(location))
 }