Implement rprompt

edit/attr.go

@@ -8,6 +8,7 @@ var (
 	attrForCurrentCompletion = "7"
 	attrForCompleted = ";4"
 	attrForMode = "1;7;33"
+	attrForRprompt = "7"
 )
 
 var attrForType = map[parse.ItemType]string{

edit/editor.go

@@ -23,7 +23,7 @@ const (
 type bufferState struct {
 	// States used during ReadLine.
 	tokens []parse.Item
-	prompt, line, tip string
+	prompt, rprompt, line, tip string
 	mode bufferMode
 	completion *completion
 	dot int
@@ -35,6 +35,8 @@ func (bs *bufferState) finish() {
 	bs.mode = ModeInsert
 	bs.completion = nil
 	bs.dot = len(bs.line)
+	// TODO Perhaps make it optional to NOT clear the rprompt
+	bs.rprompt = ""
 }
 
 // Editor keeps the status of the line editor.
@@ -185,8 +187,9 @@ func (ed *Editor) acceptCompletion() {
 }
 
 // ReadLine reads a line interactively.
-func (ed *Editor) ReadLine(prompt string) (lr LineRead) {
+func (ed *Editor) ReadLine(prompt string, rprompt string) (lr LineRead) {
 	ed.prompt = prompt
+	ed.rprompt = rprompt
 	ed.line = ""
 	ed.mode = ModeInsert
 	ed.tip = ""

edit/writer.go

@@ -220,6 +220,15 @@ func (w *writer) refresh(bs *bufferState) error {
 		}
 	}
 
+	// Write rprompt
+	padding := w.width - 1 - w.cursor.col - wcwidths(bs.rprompt)
+	if padding >= 1 {
+		w.writes(strings.Repeat(" ", padding))
+		w.currentAttr = attrForRprompt
+		w.writes(bs.rprompt)
+		w.currentAttr = ""
+	}
+
 	w.indent = 0
 
 	if bs.mode != ModeInsert {

main/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"os"
 	"fmt"
+	"os/user"
 	"../parse"
 	"../edit"
 	"../eval"
@@ -18,6 +19,17 @@ func main() {
 	ev := eval.NewEvaluator(os.Environ())
 	cmd_no := 0
 
+	username := "???"
+	user, err := user.Current()
+	if err == nil {
+		username = user.Username
+	}
+	hostname, err := os.Hostname()
+	if err != nil {
+		hostname = "???"
+	}
+	rprompt := username + "@" + hostname
+
 	for {
 		cmd_no++
 		name := fmt.Sprintf("<tty %d>", cmd_no)
@@ -28,7 +40,7 @@ func main() {
 		}
 
 		prompt := util.Getwd() + "> "
-		lr := ed.ReadLine(prompt)
+		lr := ed.ReadLine(prompt, rprompt)
 		err = ed.Cleanup()
 		if err != nil {
 			panic(err)