Allow empty pointer and marker

Close #3879

src/options.go

@@ -450,7 +450,7 @@ type Options struct {
 	Prompt       string
 	Pointer      *string
 	Marker       *string
-	MarkerMulti  [3]string
+	MarkerMulti  *[3]string
 	Query        string
 	Select1      bool
 	Exit0        bool
@@ -555,6 +555,7 @@ func defaultOptions() *Options {
 		Prompt:       "> ",
 		Pointer:      nil,
 		Marker:       nil,
+		MarkerMulti:  nil,
 		Query:        "",
 		Select1:      false,
 		Exit0:        false,
@@ -1862,7 +1863,10 @@ func parseMargin(opt string, margin string) ([4]sizeSpec, error) {
 	return [4]sizeSpec{}, errors.New("invalid " + opt + ": " + margin)
 }
 
-func parseMarkerMultiLine(str string) ([3]string, error) {
+func parseMarkerMultiLine(str string) (*[3]string, error) {
+	if str == "" {
+		return &[3]string{}, nil
+	}
 	gr := uniseg.NewGraphemes(str)
 	parts := []string{}
 	totalWidth := 0
@@ -1874,7 +1878,7 @@ func parseMarkerMultiLine(str string) ([3]string, error) {
 
 	result := [3]string{}
 	if totalWidth != 3 && totalWidth != 6 {
-		return result, fmt.Errorf("invalid total marker width: %d (expected: 3 or 6)", totalWidth)
+		return &result, fmt.Errorf("invalid total marker width: %d (expected: 0, 3 or 6)", totalWidth)
 	}
 
 	expected := totalWidth / 3
@@ -1890,7 +1894,7 @@ func parseMarkerMultiLine(str string) ([3]string, error) {
 			break
 		}
 	}
-	return result, nil
+	return &result, nil
 }
 
 func parseOptions(index *int, opts *Options, allArgs []string) error {
@@ -2699,9 +2703,6 @@ func parseOptions(index *int, opts *Options, allArgs []string) error {
 }
 
 func validateSign(sign string, signOptName string) error {
-	if sign == "" {
-		return fmt.Errorf("%v cannot be empty", signOptName)
-	}
 	if uniseg.StringWidth(sign) > 2 {
 		return fmt.Errorf("%v display width should be up to 2", signOptName)
 	}
@@ -2768,34 +2769,45 @@ func postProcessOptions(opts *Options) error {
 		opts.Pointer = &defaultPointer
 	}
 
+	multiLine := opts.MultiLine && opts.ReadZero
 	markerLen := 1
 	if opts.Marker == nil {
-		// "▎" looks better, but not all terminals render it correctly
-		defaultMarker := "┃"
-		if !opts.Unicode {
-			defaultMarker = ">"
+		if multiLine && opts.MarkerMulti != nil && opts.MarkerMulti[0] == "" {
+			empty := ""
+			opts.Marker = &empty
+			markerLen = 0
+		} else {
+			// "▎" looks better, but not all terminals render it correctly
+			defaultMarker := "┃"
+			if !opts.Unicode {
+				defaultMarker = ">"
+			}
+			opts.Marker = &defaultMarker
 		}
-		opts.Marker = &defaultMarker
 	} else {
 		markerLen = uniseg.StringWidth(*opts.Marker)
 	}
 
 	markerMultiLen := 1
-	if len(opts.MarkerMulti[0]) == 0 {
-		if opts.Unicode {
-			opts.MarkerMulti = [3]string{"╻", "┃", "╹"}
+	if opts.MarkerMulti == nil {
+		if !multiLine && *opts.Marker == "" {
+			opts.MarkerMulti = &[3]string{}
+			markerMultiLen = 0
+		} else if opts.Unicode {
+			opts.MarkerMulti = &[3]string{"╻", "┃", "╹"}
 		} else {
-			opts.MarkerMulti = [3]string{".", "|", "'"}
+			opts.MarkerMulti = &[3]string{".", "|", "'"}
 		}
 	} else {
 		markerMultiLen = uniseg.StringWidth(opts.MarkerMulti[0])
 	}
-	if markerMultiLen > markerLen {
-		padded := *opts.Marker + " "
+	diff := markerMultiLen - markerLen
+	if diff > 0 {
+		padded := *opts.Marker + strings.Repeat(" ", diff)
 		opts.Marker = &padded
-	} else if markerMultiLen < markerLen {
+	} else if diff < 0 {
 		for idx := range opts.MarkerMulti {
-			opts.MarkerMulti[idx] += " "
+			opts.MarkerMulti[idx] += strings.Repeat(" ", -diff)
 		}
 	}