time: revert CL 78735 (was: space padding using underscore)

CL 78735 description:

    time: add space padding layout strings(using underscore) for not only day but others

    As mentioned in #22802, only day component of layout string has space
    padding(represented by one underscore before its placeholder). This
    commit expands the rule for month, hour, minute and second.

    Updates #22802 (maybe fixes it)

Revert this CL because it breaks currently working formats that happen
to use underscores.

Fixes #23259

Change-Id: I64acaaca9b5b74785ee0f0be7910574e87daa649
Reviewed-on: https://go-review.googlesource.com/85998
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

2 files changed, 10 insertions, 96 deletions

diff --git a/src/time/format.go b/src/time/format.go
index 4f28e3be0c..a60474f026 100644
--- a/src/time/format.go
+++ b/src/time/format.go
@@ -90,7 +90,6 @@ const (
 	stdLongMonth             = iota + stdNeedDate  // "January"
 	stdMonth                                       // "Jan"
 	stdNumMonth                                    // "1"
-	stdUnderMonth                                  // "_1"
 	stdZeroMonth                                   // "01"
 	stdLongWeekDay                                 // "Monday"
 	stdWeekDay                                     // "Mon"
@@ -99,13 +98,10 @@ const (
 	stdZeroDay                                     // "02"
 	stdHour                  = iota + stdNeedClock // "15"
 	stdHour12                                      // "3"
-	stdUnderHour12                                 // "_3"
 	stdZeroHour12                                  // "03"
 	stdMinute                                      // "4"
-	stdUnderMinute                                 // "_4"
 	stdZeroMinute                                  // "04"
 	stdSecond                                      // "5"
-	stdUnderSecond                                 // "_5"
 	stdZeroSecond                                  // "05"
 	stdLongYear              = iota + stdNeedDate  // "2006"
 	stdYear                                        // "06"
@@ -191,24 +187,13 @@ func nextStdChunk(layout string) (prefix string, std int, suffix string) {
 			}
 			return layout[0:i], stdDay, layout[i+1:]
 
-		case '_': // _1, _2, _2006, _3, _4, _5
-			if len(layout) >= i+2 {
-				switch layout[i+1] {
-				case '1':
-					return layout[0:i], stdUnderMonth, layout[i+2:]
-				case '2':
-					//_2006 is really a literal _, followed by stdLongYear
-					if len(layout) >= i+5 && layout[i+1:i+5] == "2006" {
-						return layout[0 : i+1], stdLongYear, layout[i+5:]
-					}
-					return layout[0:i], stdUnderDay, layout[i+2:]
-				case '3':
-					return layout[0:i], stdUnderHour12, layout[i+2:]
-				case '4':
-					return layout[0:i], stdUnderMinute, layout[i+2:]
-				case '5':
-					return layout[0:i], stdUnderSecond, layout[i+2:]
+		case '_': // _2, _2006
+			if len(layout) >= i+2 && layout[i+1] == '2' {
+				//_2006 is really a literal _, followed by stdLongYear
+				if len(layout) >= i+5 && layout[i+1:i+5] == "2006" {
+					return layout[0 : i+1], stdLongYear, layout[i+5:]
 				}
+				return layout[0:i], stdUnderDay, layout[i+2:]
 			}
 
 		case '3':
@@ -559,11 +544,6 @@ func (t Time) AppendFormat(b []byte, layout string) []byte {
 			b = append(b, m...)
 		case stdNumMonth:
 			b = appendInt(b, int(month), 0)
-		case stdUnderMonth:
-			if month < 10 {
-				b = append(b, ' ')
-			}
-			b = appendInt(b, int(month), 0)
 		case stdZeroMonth:
 			b = appendInt(b, int(month), 2)
 		case stdWeekDay:
@@ -589,16 +569,6 @@ func (t Time) AppendFormat(b []byte, layout string) []byte {
 				hr = 12
 			}
 			b = appendInt(b, hr, 0)
-		case stdUnderHour12:
-			// Noon is 12PM, midnight is 12AM.
-			hr := hour % 12
-			if hr == 0 {
-				hr = 12
-			}
-			if hr < 10 {
-				b = append(b, ' ')
-			}
-			b = appendInt(b, hr, 0)
 		case stdZeroHour12:
 			// Noon is 12PM, midnight is 12AM.
 			hr := hour % 12
@@ -608,20 +578,10 @@ func (t Time) AppendFormat(b []byte, layout string) []byte {
 			b = appendInt(b, hr, 2)
 		case stdMinute:
 			b = appendInt(b, min, 0)
-		case stdUnderMinute:
-			if min < 10 {
-				b = append(b, ' ')
-			}
-			b = appendInt(b, min, 0)
 		case stdZeroMinute:
 			b = appendInt(b, min, 2)
 		case stdSecond:
 			b = appendInt(b, sec, 0)
-		case stdUnderSecond:
-			if sec < 10 {
-				b = append(b, ' ')
-			}
-			b = appendInt(b, sec, 0)
 		case stdZeroSecond:
 			b = appendInt(b, sec, 2)
 		case stdPM:
@@ -886,10 +846,7 @@ func parse(layout, value string, defaultLocation, local *Location) (Time, error)
 		case stdLongMonth:
 			month, value, err = lookup(longMonthNames, value)
 			month++
-		case stdNumMonth, stdUnderMonth, stdZeroMonth:
-			if std == stdUnderMonth && len(value) > 0 && value[0] == ' ' {
-				value = value[1:]
-			}
+		case stdNumMonth, stdZeroMonth:
 			month, value, err = getnum(value, std == stdZeroMonth)
 			if month <= 0 || 12 < month {
 				rangeErrString = "month"
@@ -913,26 +870,17 @@ func parse(layout, value string, defaultLocation, local *Location) (Time, error)
 			if hour < 0 || 24 <= hour {
 				rangeErrString = "hour"
 			}
-		case stdHour12, stdUnderHour12, stdZeroHour12:
-			if std == stdUnderHour12 && len(value) > 0 && value[0] == ' ' {
-				value = value[1:]
-			}
+		case stdHour12, stdZeroHour12:
 			hour, value, err = getnum(value, std == stdZeroHour12)
 			if hour < 0 || 12 < hour {
 				rangeErrString = "hour"
 			}
-		case stdMinute, stdUnderMinute, stdZeroMinute:
-			if std == stdUnderMinute && len(value) > 0 && value[0] == ' ' {
-				value = value[1:]
-			}
+		case stdMinute, stdZeroMinute:
 			min, value, err = getnum(value, std == stdZeroMinute)
 			if min < 0 || 60 <= min {
 				rangeErrString = "minute"
 			}
-		case stdSecond, stdUnderSecond, stdZeroSecond:
-			if std == stdUnderSecond && len(value) > 0 && value[0] == ' ' {
-				value = value[1:]
-			}
+		case stdSecond, stdZeroSecond:
 			sec, value, err = getnum(value, std == stdZeroSecond)
 			if sec < 0 || 60 <= sec {
 				rangeErrString = "second"
diff --git a/src/time/format_test.go b/src/time/format_test.go
index 9871976ad5..6d27f468c7 100644
--- a/src/time/format_test.go
+++ b/src/time/format_test.go
@@ -116,18 +116,6 @@ func TestFormatShortYear(t *testing.T) {
 	}
 }
 
-// issue 22802.
-func TestFormatSpacePadding(t *testing.T) {
-	for i := 9; i <= 10; i++ {
-		time := Date(2001, Month(i), i, i, i, i, 700000000, UTC)
-		result := time.Format("2006-_1-_2 _3:_4:_5")
-		want := fmt.Sprintf("2001-%2d-%2d %2d:%2d:%2d", i, i, i, i, i)
-		if result != want {
-			t.Errorf("SpacePadding expected %q got %q", want, result)
-		}
-	}
-}
-
 type ParseTest struct {
 	name       string
 	format     string
@@ -639,25 +627,3 @@ func TestUnderscoreTwoThousand(t *testing.T) {
 		t.Errorf("Incorrect minute, got %d", m)
 	}
 }
-
-// issue 22802.
-func TestParseSpacePadding(t *testing.T) {
-	format := "2006-_1-_2 _3:_4:_5"
-	input := "2017- 9- 6  8: 4: 2"
-	time, err := Parse(format, input)
-	if err != nil {
-		t.Error(err)
-	}
-	if y, m, d := time.Date(); y != 2017 || m != 9 || d != 6 {
-		t.Errorf("Incorrect y/m/d, got %d/%d/%d", y, m, d)
-	}
-	if h := time.Hour(); h != 8 {
-		t.Errorf("Incorrect hour, got %d", h)
-	}
-	if m := time.Minute(); m != 4 {
-		t.Errorf("Incorrect minute, got %d", m)
-	}
-	if s := time.Second(); s != 2 {
-		t.Errorf("Incorrect second, got %d", s)
-	}
-}