copy changes from #102 (#103)

Author: delaneyj

actions.go

@@ -14,6 +14,8 @@ type Actions interface {
 	ReadLine() string
 	// ReadLineErr is ReadLine but returns error as well
 	ReadLineErr() (string, error)
+	// ReadLineWithDefault reads a line from standard input with default value.
+	ReadLineWithDefault(string) string
 	// ReadPassword reads password from standard input without echoing the characters.
 	// Note that this only works as expected when the standard input is a terminal.
 	ReadPassword() string
@@ -85,6 +87,13 @@ func (s *shellActionsImpl) ReadLineErr() (string, error) {
 	return s.readLine()
 }
 
+func (s *shellActionsImpl) ReadLineWithDefault(defaultValue string) string {
+	s.reader.defaultValue = defaultValue
+	line, _ := s.readLine()
+	s.reader.defaultValue = ""
+	return line
+}
+
 func (s *shellActionsImpl) ReadPassword() string {
 	return s.reader.readPassword()
 }

reader.go

@@ -25,6 +25,7 @@ type (
 		showPrompt   bool
 		completer    readline.AutoCompleter
 		sync.Mutex
+		defaultValue string
 	}
 )
 
@@ -87,7 +88,7 @@ func (s *shellReader) readLine(consumer chan lineString) {
 	// use printed statement as prompt
 	s.scanner.SetPrompt(prompt)
 
-	line, err := s.scanner.Readline()
+	line, err := s.scanner.ReadlineWithDefault(s.defaultValue)
 
 	// reset prompt
 	s.scanner.SetPrompt(shellPrompt)