feat: add right prompt (closes #111)

api.go

@@ -35,7 +35,7 @@ var exports = map[string]util.LuaExport{
 	"hinter": {hlhinter, 1, false},
 	"multiprompt": {hlmultiprompt, 1, false},
 	"prependPath": {hlprependPath, 1, false},
-	"prompt": {hlprompt, 1, false},
+	"prompt": {hlprompt, 1, true},
 	"inputMode": {hlinputMode, 1, false},
 	"interval": {hlinterval, 2, false},
 	"read": {hlread, 1, false},
@@ -315,15 +315,31 @@ These will be formatted and replaced with the appropriate values.
 --- @param str string
 */
 func hlprompt(t *rt.Thread, c *rt.GoCont) (rt.Cont, error) {
-	var prompt string
 	err := c.Check1Arg()
-	if err == nil {
-		prompt, err = c.StringArg(0)
-	}
 	if err != nil {
 		return nil, err
 	}
-	lr.SetPrompt(fmtPrompt(prompt))
+	p, err := c.StringArg(0)
+	if err != nil {
+		return nil, err
+	}
+	typ := "left"
+	if len(c.Etc()) != 0 {
+		ltyp := c.Etc()[0]
+		var ok bool
+		typ, ok = ltyp.TryString()
+		if !ok {
+			return nil, errors.New("bad argument to run (expected string, got " + ltyp.TypeName() + ")")
+		}
+	}
+
+	switch typ {
+		case "left":
+			prompt = p
+			lr.SetPrompt(fmtPrompt(prompt))
+		case "right":
+			lr.SetRightPrompt(fmtPrompt(p))
+	}
 
 	return c.Next(), nil
 }

readline/instance.go

@@ -30,11 +30,13 @@ type Instance struct {
 	Multiline       bool   // If set to true, the shell will have a two-line prompt.
 	MultilinePrompt string // If multiline is true, this is the content of the 2nd line.
 
-	mainPrompt     string // If multiline true, the full prompt string / If false, the 1st line of the prompt
+	mainPrompt      string // If multiline true, the full prompt string / If false, the 1st line of the prompt
-	realPrompt     []rune // The prompt that is actually on the same line as the beginning of the input line.
+	rightPrompt     string
-	defaultPrompt  []rune
+	rightPromptLen  int
-	promptLen      int
+	realPrompt      []rune // The prompt that is actually on the same line as the beginning of the input line.
-	stillOnRefresh bool // True if some logs have printed asynchronously since last loop. Check refresh prompt funcs
+	defaultPrompt   []rune
+	promptLen       int
+	stillOnRefresh  bool // True if some logs have printed asynchronously since last loop. Check refresh prompt funcs
 
 	//
 	// Input Line ---------------------------------------------------------------------------------

readline/prompt.go

@@ -14,6 +14,11 @@ func (rl *Instance) SetPrompt(s string) {
 	rl.computePrompt()
 }
 
+func (rl *Instance) SetRightPrompt(s string) {
+	rl.rightPrompt = s
+	rl.computePrompt()
+}
+
 // RefreshPromptLog - A simple function to print a string message (a log, or more broadly,
 // an asynchronous event) without bothering the user, and by "pushing" the prompt below the message.
 func (rl *Instance) RefreshPromptLog(log string) (err error) {
@@ -185,6 +190,7 @@ func (rl *Instance) computePrompt() (prompt []rune) {
 
 	// Strip color escapes
 	rl.promptLen = getRealLength(string(rl.realPrompt))
+	rl.rightPromptLen = getRealLength(string(rl.rightPrompt))
 	
 	return
 }
@@ -205,3 +211,11 @@ func getRealLength(s string) (l int) {
 	stripped := ansi.Strip(s)
 	return uniseg.GraphemeClusterCount(stripped)
 }
+
+func (rl *Instance) echoRightPrompt() {
+	if rl.fullX < GetTermWidth() - rl.rightPromptLen - 1 {
+		moveCursorForwards(GetTermWidth())
+		moveCursorBackwards(rl.rightPromptLen)
+		print(rl.rightPrompt)
+	}
+}

readline/readline.go

@@ -564,6 +564,8 @@ func (rl *Instance) editorInput(r []rune) {
 		rl.writeHintText()
 	}
 
+	rl.echoRightPrompt()
+
 	if len(rl.multisplit) == 0 {
 		rl.syntaxCompletion()
 	}

readline/update.go

@@ -121,6 +121,8 @@ func (rl *Instance) renderHelpers() {
 		rl.writeHintText()
 	}
 
+	rl.echoRightPrompt()
+
 	// Go at beginning of first line after input remainder
 	moveCursorDown(rl.fullY - rl.posY)
 	moveCursorBackwards(GetTermWidth())

rl.go

@@ -281,6 +281,13 @@ func (lr *lineReader) SetPrompt(p string) {
 	}
 }
 
+func (lr *lineReader) SetRightPrompt(p string) {
+	lr.rl.SetRightPrompt(p)
+	if initialized && !running {
+		lr.rl.RefreshPromptInPlace("")
+	}
+}
+
 func (lr *lineReader) AddHistory(cmd string) {
 	fileHist.Write(cmd)
 }