Add --ghost=TEXT to display a ghost text when the input is empty

src/options.go

@@ -136,6 +136,7 @@ Usage: fzf [options]
     --separator=STR          Draw horizontal separator on info line using the string
                              (default: '─' or '-')
     --no-separator           Hide info line separator
+    --ghost=TEXT             Ghost text to display when the input is empty
     --filepath-word          Make word-wise movements respect path separators
     --input-border[=STYLE]   Draw border around the input section
                              [rounded|sharp|bold|block|thinblock|double|horizontal|vertical|
@@ -574,6 +575,7 @@ type Options struct {
 	InfoStyle         infoStyle
 	InfoPrefix        string
 	InfoCommand       string
+	Ghost             string
 	Separator         *string
 	JumpLabels        string
 	Prompt            string
@@ -689,6 +691,7 @@ func defaultOptions() *Options {
 		ScrollOff:    3,
 		FileWord:     false,
 		InfoStyle:    infoDefault,
+		Ghost:        "",
 		Separator:    nil,
 		JumpLabels:   defaultJumpLabels,
 		Prompt:       "> ",
@@ -2597,6 +2600,10 @@ func parseOptions(index *int, opts *Options, allArgs []string) error {
 		case "--no-separator":
 			nosep := ""
 			opts.Separator = &nosep
+		case "--ghost":
+			if opts.Ghost, err = nextString("ghost text required"); err != nil {
+				return err
+			}
 		case "--scrollbar":
 			given, bar := optionalNextString()
 			if given {

src/terminal.go

@@ -234,6 +234,7 @@ type Terminal struct {
 	wrap               bool
 	wrapSign           string
 	wrapSignWidth      int
+	ghost              string
 	separator          labelPrinter
 	separatorLen       int
 	spinner            []string
@@ -847,6 +848,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		infoCommand:        opts.InfoCommand,
 		infoStyle:          opts.InfoStyle,
 		infoPrefix:         opts.InfoPrefix,
+		ghost:              opts.Ghost,
 		separator:          nil,
 		spinner:            makeSpinner(opts.Unicode),
 		promptString:       opts.Prompt,
@@ -2359,6 +2361,11 @@ func (t *Terminal) printPrompt() {
 	t.prompt()
 
 	before, after := t.updatePromptOffset()
+	if len(before) == 0 && len(after) == 0 && len(t.ghost) > 0 {
+		w.CPrint(tui.ColInput.WithAttr(tui.Dim), t.ghost)
+		return
+	}
+
 	color := tui.ColInput
 	if t.paused {
 		color = tui.ColDisabled