#15: fix prefix completer

complete_helper.go

@@ -12,9 +12,7 @@ func NewPrefixCompleter(pc ...*PrefixCompleter) *PrefixCompleter {
 }
 
 func PcItem(name string, pc ...*PrefixCompleter) *PrefixCompleter {
-	if len(pc) != 0 {
-		name += " "
-	}
+	name += " "
 	return &PrefixCompleter{
 		Name:     []rune(name),
 		Children: pc,
@@ -28,7 +26,11 @@ func (p *PrefixCompleter) Do(line []rune, pos int) (newLine [][]rune, offset int
 	for _, child := range p.Children {
 		if len(line) >= len(child.Name) {
 			if runes.HasPrefix(line, child.Name) {
-				newLine = append(newLine, child.Name)
+				if len(line) == len(child.Name) {
+					newLine = append(newLine, []rune{' '})
+				} else {
+					newLine = append(newLine, child.Name)
+				}
 				offset = len(child.Name)
 				lineCompleter = child
 				goNext = true

example/main.go

@@ -33,8 +33,12 @@ var completer = readline.NewPrefixCompleter(
 	readline.PcItem("bye"),
 	readline.PcItem("help"),
 	readline.PcItem("go",
-		readline.PcItem("build"),
-		readline.PcItem("install"),
+		readline.PcItem("build", readline.PcItem("-o"), readline.PcItem("-v")),
+		readline.PcItem("install",
+			readline.PcItem("-v"),
+			readline.PcItem("-vv"),
+			readline.PcItem("-vvv"),
+		),
 		readline.PcItem("test"),
 	),
 	readline.PcItem("sleep"),