Improve command bar completion

cmd/micro/messenger.go

@@ -322,7 +322,7 @@ func (m *Messenger) Prompt(prompt, placeholder, historyType string, completionTy
 					chosen = chosen + CommonSubstring(suggestions...)
 				}
 
-				if chosen != "" {
+				if len(suggestions) != 0 {
 					m.response = shellwords.Join(append(args[:len(args)-1], chosen)...)
 					m.cursorx = Count(m.response)
 				}

cmd/micro/shellwords/shellwords.go

@@ -168,19 +168,10 @@ func Join(args ...string) string {
 
 		for _, b := range w {
 			switch b {
-			case 'a', 'b', 'c', 'd', 'e', 'f', 'g',
-				'h', 'i', 'j', 'k', 'l', 'm', 'n',
-				'o', 'p', 'q', 'r', 's', 't', 'u',
-				'v', 'w', 'x', 'y', 'z',
-				'A', 'B', 'C', 'D', 'E', 'F', 'G',
-				'H', 'I', 'J', 'K', 'L', 'M', 'N',
-				'O', 'P', 'Q', 'R', 'S', 'T', 'U',
-				'V', 'W', 'X', 'Y', 'Z',
-				'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
-				'_', '-', '.', ',', ':', '/', '@':
+			case ' ', '\t', '\r', '\n':
+				buf.WriteByte('\\')
 				buf.WriteString(string(b))
 			default:
-				buf.WriteByte('\\')
 				buf.WriteString(string(b))
 			}
 		}