Add --preview-window=default for resetting the options

src/options.go

@@ -84,6 +84,7 @@ const usage = `usage: fzf [options]
                           [:[no]wrap][:[no]cycle][:[no]hidden]
                           [:rounded|sharp|noborder]
                           [:+SCROLL[-OFFSET]]
+                          [:default]
 
   Scripting
     -q, --query=STR       Start the finder with the given query
@@ -226,6 +227,10 @@ type Options struct {
 	Version     bool
 }
 
+func defaultPreviewOpts(command string) previewOpts {
+	return previewOpts{command, posRight, sizeSpec{50, true}, "", false, false, false, tui.BorderRounded}
+}
+
 func defaultOptions() *Options {
 	return &Options{
 		Fuzzy:       true,
@@ -265,7 +270,7 @@ func defaultOptions() *Options {
 		ToggleSort:  false,
 		Expect:      make(map[int]string),
 		Keymap:      make(map[int][]action),
-		Preview:     previewOpts{"", posRight, sizeSpec{50, true}, "", false, false, false, tui.BorderRounded},
+		Preview:     defaultPreviewOpts(""),
 		PrintQuery:  false,
 		ReadZero:    false,
 		Printer:     func(str string) { fmt.Println(str) },
@@ -1001,6 +1006,8 @@ func parsePreviewWindow(opts *previewOpts, input string) {
 	for _, token := range tokens {
 		switch token {
 		case "":
+		case "default":
+			*opts = defaultPreviewOpts(opts.command)
 		case "hidden":
 			opts.hidden = true
 		case "nohidden":
@@ -1278,7 +1285,7 @@ func parseOptions(opts *Options, allArgs []string) {
 			opts.Preview.command = ""
 		case "--preview-window":
 			parsePreviewWindow(&opts.Preview,
-				nextString(allArgs, &i, "preview window layout required: [up|down|left|right][:SIZE[%]][:rounded|sharp|noborder][:wrap][:cycle][:hidden][:+SCROLL[-OFFSET]]"))
+				nextString(allArgs, &i, "preview window layout required: [up|down|left|right][:SIZE[%]][:rounded|sharp|noborder][:wrap][:cycle][:hidden][:+SCROLL[-OFFSET]][:default]"))
 		case "--height":
 			opts.Height = parseHeight(nextString(allArgs, &i, "height required: HEIGHT[%]"))
 		case "--min-height":

src/options_test.go

@@ -417,6 +417,13 @@ func TestPreviewOpts(t *testing.T) {
 		opts.Preview.size.size == 15) {
 		t.Error(opts.Preview)
 	}
+	opts = optsFor("--preview=foo", "--preview-window=up", "--preview-window=default:70%")
+	if !(opts.Preview.command == "foo" &&
+		opts.Preview.position == posRight &&
+		opts.Preview.size.percent == true &&
+		opts.Preview.size.size == 70) {
+		t.Error(opts.Preview)
+	}
 }
 
 func TestAdditiveExpect(t *testing.T) {