Add lots more strftime flags

Author: bvisness

utils.go

@@ -100,10 +100,47 @@ func (fs *flagScanner) Next() (byte, bool) {
 }
 
 var cDateFlagToGo = map[byte]string{
-	'a': "mon", 'A': "Monday", 'b': "Jan", 'B': "January", 'c': "02 Jan 06 15:04 MST", 'd': "02",
-	'F': "2006-01-02", 'H': "15", 'I': "03", 'm': "01", 'M': "04", 'p': "PM", 'P': "pm", 'S': "05",
-	'x': "15/04/05", 'X': "15:04:05", 'y': "06", 'Y': "2006", 'z': "-0700", 'Z': "MST"}
+	// Formatting
+	'n': "\n",
+	't': "\t",
 
+	// Year
+	'Y': "2006", 'y': "06",
+
+	// Month
+	'b': "Jan", 'B': "January", // TODO: %^B, %^b
+	'm': "01", // TODO: %-m, %_m
+
+	// Day of the year/month
+	'j': "002",
+	'd': "02", 'e': "_2", // TODO: %-d
+
+	// Day of the week
+	'a': "Mon", 'A': "Monday", // TODO: %^A, %^a
+
+	// Hour, minute, second
+	'H': "15",
+	'I': "03", 'l': "3",
+	'M': "04",
+	'S': "05",
+
+	// Other
+	'c': "02 Jan 06 15:04 MST",
+	'x': "01/02/06", 'X': "15:04:05",
+	'D': "01/02/06",
+	'F': "2006-01-02",
+	'r': "03:04:05 PM", 'R': "15:04",
+	'T': "15:04:05",
+	'p': "PM", 'P': "pm",
+	'z': "-0700", 'Z': "MST",
+
+	// Many other flags are handled in the body of strftime since they cannot
+	// be represented in Go format strings.
+}
+
+// This implementation of strftime is inspired by both the C spec and Ruby's
+// extensions. This allows for flags like %-d, which provides the day of the
+// month without padding (1..31 instead of 01..31).
 func strftime(t time.Time, cfmt string) string {
 	sc := newFlagScanner('%', "", "", cfmt)
 	for c, eos := sc.Next(); !eos; c, eos = sc.Next() {
@@ -113,6 +150,15 @@ func strftime(t time.Time, cfmt string) string {
 					sc.AppendString(t.Format(v))
 				} else {
 					switch c {
+					case 'G':
+						isoYear, _ := t.ISOWeek()
+						sc.AppendString(fmt.Sprint(isoYear))
+					case 'g':
+						isoYear, _ := t.ISOWeek()
+						sc.AppendString(fmt.Sprint(isoYear)[2:])
+					case 'V':
+						_, isoWeek := t.ISOWeek()
+						sc.AppendString(fmt.Sprint(isoWeek))
 					case 'w':
 						sc.AppendString(fmt.Sprint(int(t.Weekday())))
 					default:

utils_test.go

@@ -0,0 +1,70 @@
+package lua
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+func TestStrftime(t *testing.T) {
+	type testCase struct {
+		T        time.Time
+		Fmt      string
+		Expected string
+	}
+
+	t1 := time.Date(2016, time.February, 3, 13, 23, 45, 123, time.FixedZone("Plus2", 60*60*2))
+	t2 := time.Date(1945, time.September, 6, 7, 35, 4, 989, time.FixedZone("Minus5", 60*60*-5))
+
+	cases := []testCase{
+		{t1, "foo%nbar%tbaz 100%% cool", "foo\nbar\tbaz 100% cool"},
+
+		{t1, "%Y %y", "2016 16"},
+		{t1, "%G %g", "2016 16"},
+		{t1, "%b %B %m", "Feb February 02"},
+		{t1, "%V", "5"},
+		{t1, "%w", "3"},
+		{t1, "%j", "034"},
+		{t1, "%d", "03"},
+		{t1, "%e", " 3"},
+		{t1, "%a %A", "Wed Wednesday"},
+		{t1, "%H %I %l", "13 01 1"},
+		{t1, "%M", "23"},
+		{t1, "%S", "45"},
+		{t1, "%c", "03 Feb 16 13:23 Plus2"},
+		{t1, "%D %x", "02/03/16 02/03/16"},
+		{t1, "%F", "2016-02-03"},
+		{t1, "%r", "01:23:45 PM"},
+		{t1, "%R %T %X", "13:23 13:23:45 13:23:45"},
+		{t1, "%p %P", "PM pm"},
+		{t1, "%z %Z", "+0200 Plus2"},
+
+		{t2, "%Y %y", "1945 45"},
+		{t2, "%G %g", "1945 45"},
+		{t2, "%b %B %m", "Sep September 09"},
+		{t2, "%V", "36"},
+		{t2, "%w", "4"},
+		{t2, "%j", "249"},
+		{t2, "%d", "06"},
+		{t2, "%e", " 6"},
+		{t2, "%a %A", "Thu Thursday"},
+		{t2, "%H %I %l", "07 07 7"},
+		{t2, "%M", "35"},
+		{t2, "%S", "04"},
+		{t2, "%c", "06 Sep 45 07:35 Minus5"},
+		{t2, "%D %x", "09/06/45 09/06/45"},
+		{t2, "%F", "1945-09-06"},
+		{t2, "%r", "07:35:04 AM"},
+		{t2, "%R %T %X", "07:35 07:35:04 07:35:04"},
+		{t2, "%p %P", "AM am"},
+		{t2, "%z %Z", "-0500 Minus5"},
+	}
+	for i, c := range cases {
+		t.Run(fmt.Sprintf("Case %d (\"%s\")", i, c.Fmt), func(t *testing.T) {
+			actual := strftime(c.T, c.Fmt)
+			if actual != c.Expected {
+				t.Errorf("bad strftime: expected \"%s\" but got \"%s\"", c.Expected, actual)
+			}
+		})
+	}
+}