add option for default win size

input.go

@@ -16,6 +16,8 @@ type ConsoleParser interface {
 	TearDown() error
 	// GetWinSize returns WinSize object to represent width and height of terminal.
 	GetWinSize() *WinSize
+	// SetWinSize sets default width and height of terminal when can not be optained automatically.
+	SetWinSize(*WinSize)
 	// Read returns byte array.
 	Read() ([]byte, error)
 }

input_posix.go

@@ -14,6 +14,8 @@ const maxReadBytes = 1024
 // PosixParser is a ConsoleParser implementation for POSIX environment.
 type PosixParser struct {
 	fd          int
+	row         uint16
+	col         uint16
 	origTermios syscall.Termios
 }
 
@@ -56,12 +58,24 @@ func (t *PosixParser) GetWinSize() *WinSize {
 	if err != nil {
 		panic(err)
 	}
+	if ws.Row == 0 {
+		ws.Row = t.row
+	}
+	if ws.Col == 0 {
+		ws.Col = t.col
+	}
 	return &WinSize{
 		Row: ws.Row,
 		Col: ws.Col,
 	}
 }
 
+// SetWinSize sets default width and height of terminal when can not be optained automatically.
+func (t *PosixParser) SetWinSize(ws *WinSize) {
+	t.col = ws.Col
+	t.row = ws.Row
+}
+
 var _ ConsoleParser = &PosixParser{}
 
 // NewStandardInputParser returns ConsoleParser object to read from stdin.

input_windows.go

@@ -19,6 +19,8 @@ var procGetNumberOfConsoleInputEvents = kernel32.NewProc("GetNumberOfConsoleInpu
 
 // WindowsParser is a ConsoleParser implementation for Win32 console.
 type WindowsParser struct {
+	row int
+	col int
 	tty *tty.TTY
 }
 
@@ -71,12 +73,24 @@ func (p *WindowsParser) GetWinSize() *WinSize {
 	if err != nil {
 		panic(err)
 	}
+	if h == 0 {
+		h = p.row
+	}
+	if w == 0 {
+		w = p.col
+	}
 	return &WinSize{
 		Row: uint16(h),
 		Col: uint16(w),
 	}
 }
 
+// SetWinSize sets default width and height of terminal when can not be optained automatically.
+func (t *PosixParser) SetWinSize(ws *WinSize) {
+	t.col = int(ws.Col)
+	t.row = int(ws.Row)
+}
+
 // NewStandardInputParser returns ConsoleParser object to read from stdin.
 func NewStandardInputParser() *WindowsParser {
 	return &WindowsParser{}

option.go

@@ -266,6 +266,14 @@ func OptionSetExitCheckerOnInput(fn ExitChecker) Option {
 	}
 }
 
+// OptionSetDefaultWinSize set fallback for win size when not provided by tty
+func OptionSetDefaultWinSize(ws *WinSize) Option {
+	return func(p *Prompt) error {
+		p.in.SetWinSize(ws)
+		return nil
+	}
+}
+
 // New returns a Prompt with powerful auto-completion.
 func New(executor Executor, completer Completer, opts ...Option) *Prompt {
 	defaultWriter := NewStdoutWriter()