Use functional option pattern

main.go

@@ -45,7 +45,12 @@ func completer(b *prompt.Buffer) []string {
 }
 
 func main() {
-	pt := prompt.NewPrompt(executor, completer, 8)
+	pt := prompt.NewPrompt(
+		executor,
+		completer,
+		prompt.MaxCompletionsOption(8),
+		prompt.PrefixOption("> "),
+	)
 	defer fmt.Println("\nGoodbye!")
 	fmt.Print("Hello! This is a example appication using prompt-toolkit.\n")
 	pt.Run()

prompt/console_interface.go

@@ -0,0 +1,62 @@
+package prompt
+
+type WinSize struct {
+	Row uint16
+	Col uint16
+}
+
+type ConsoleParser interface {
+	// Setup
+	Setup() error
+	// TearDown
+	TearDown() error
+	// GetSCIICode returns ASCIICode correspond to input byte codes.
+	GetASCIICode(b []byte) *ASCIICode
+	// GetWinSize returns winsize struct which is the response of ioctl(2).
+	GetWinSize() *WinSize
+}
+
+type ConsoleWriter interface {
+	/* Write */
+
+	Write(data []byte)
+	WriteStr(data string)
+	WriteRaw(data []byte)
+	Flush() error
+
+	/* Erasing */
+
+	EraseScreen()
+	EraseUp()
+	EraseDown()
+	EraseStartOfLine()
+	EraseEndOfLine()
+	EraseLine()
+
+	/* Cursor */
+
+	ShowCursor()
+	HideCursor()
+	CursorGoTo(row, col int)
+	CursorUp(n int)
+	CursorDown(n int)
+	CursorForward(n int)
+	CursorBackward(n int)
+	AskForCPR()
+	SaveCursor()
+	UnSaveCursor()
+
+	/* Scrolling */
+
+	ScrollDown()
+	ScrollUp()
+
+	/* Title */
+
+	SetTitle(title string)
+	ClearTitle()
+
+	/* colors */
+
+	SetColor(fg, bg string) (ok bool)
+}

prompt/input.go

@@ -1,6 +0,0 @@
-package prompt
-
-type WinSize struct {
-	Row uint16
-	Col uint16
-}

prompt/option.go

@@ -0,0 +1,60 @@
+package prompt
+
+type option func(prompt *Prompt) error
+
+func ParserOption(x ConsoleParser) option {
+	return func(p *Prompt) error {
+		p.in = x
+		return nil
+	}
+}
+
+func WriterOption(x ConsoleWriter) option {
+	return func(p *Prompt) error {
+		p.renderer.out = x
+		return nil
+	}
+}
+
+func TitleOption(x string) option {
+	return func(p *Prompt) error {
+		p.title = x
+		return nil
+	}
+}
+
+func PrefixOption(x string) option {
+	return func(p *Prompt) error {
+		p.renderer.Prefix = x
+		return nil
+	}
+}
+
+func MaxCompletionsOption(x uint16) option {
+	return func(p *Prompt) error {
+		p.renderer.maxCompletions = x
+		return nil
+	}
+}
+
+func NewPrompt(executor Executor, completer Completer, opts ...option) *Prompt {
+	pt := &Prompt{
+		in: NewVT100Parser(),
+		renderer: &Render{
+			Prefix:         ">>> ",
+			out:            NewVT100Writer(),
+		},
+		title:     "Hello! this is prompt toolkit",
+		buf:       NewBuffer(),
+		executor:  executor,
+		completer: completer,
+		chosen: -1,
+	}
+
+	for _, opt := range opts {
+		if err := opt(pt); err != nil {
+			panic(err)
+		}
+	}
+	return pt
+}

prompt/prompt.go

@@ -11,7 +11,7 @@ type Executor func(*Buffer) string
 type Completer func(*Buffer) []string
 
 type Prompt struct {
-	in        *VT100Parser
+	in        ConsoleParser
 	buf       *Buffer
 	renderer  *Render
 	title     string
@@ -110,7 +110,7 @@ func readBuffer(bufCh chan []byte) {
 	}
 }
 
-func handleSignals(in *VT100Parser, exitCh chan bool, winSizeCh chan *WinSize) {
+func handleSignals(in ConsoleParser, exitCh chan bool, winSizeCh chan *WinSize) {
 	sigCh := make(chan os.Signal, 1)
 	signal.Notify(
 		sigCh,
@@ -146,19 +146,3 @@ func handleSignals(in *VT100Parser, exitCh chan bool, winSizeCh chan *WinSize) {
 		}
 	}
 }
-
-func NewPrompt(executor Executor, completer Completer, maxCompletions uint16) *Prompt {
-	return &Prompt{
-		in: NewVT100Parser(),
-		renderer: &Render{
-			Prefix:         ">>> ",
-			out:            NewVT100Writer(),
-			maxCompletions: maxCompletions,
-		},
-		title:     "Hello! this is prompt toolkit",
-		buf:       NewBuffer(),
-		executor:  executor,
-		completer: completer,
-		chosen: -1,
-	}
-}

prompt/render.go

@@ -3,9 +3,9 @@ package prompt
 type Render struct {
 	Prefix         string
 	Title          string
-	out            *VT100Writer
+	out            ConsoleWriter
 	row            uint16
-	col            uint16 // sigwinchで送られてくる列数を常に見ながら、prefixのlengthとbufferのcursor positionを比べて、completionの表示位置をずらす
+	col            uint16
 	maxCompletions uint16
 }