new readline library (#847)

readline/readline.go

@@ -0,0 +1,254 @@
+package readline
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"sync"
+	"syscall"
+)
+
+type Prompt struct {
+	Prompt         string
+	AltPrompt      string
+	Placeholder    string
+	AltPlaceholder string
+	UseAlt         bool
+}
+
+type Terminal struct {
+	m       sync.Mutex
+	wg      sync.WaitGroup
+	outchan chan rune
+}
+
+type Instance struct {
+	Prompt   *Prompt
+	Terminal *Terminal
+	History  *History
+}
+
+func New(prompt Prompt) (*Instance, error) {
+	term, err := NewTerminal()
+	if err != nil {
+		return nil, err
+	}
+
+	history, err := NewHistory()
+	if err != nil {
+		return nil, err
+	}
+
+	return &Instance{
+		Prompt:   &prompt,
+		Terminal: term,
+		History:  history,
+	}, nil
+}
+
+func (i *Instance) Readline() (string, error) {
+	prompt := i.Prompt.Prompt
+	if i.Prompt.UseAlt {
+		prompt = i.Prompt.AltPrompt
+	}
+	fmt.Printf(prompt)
+
+	termios, err := SetRawMode(syscall.Stdin)
+	if err != nil {
+		return "", err
+	}
+	defer UnsetRawMode(syscall.Stdin, termios)
+
+	buf, _ := NewBuffer(i.Prompt)
+
+	var esc bool
+	var escex bool
+	var metaDel bool
+	var bracketedPaste bool
+	var ignoreEnter bool
+
+	var currentLineBuf []rune
+
+	for {
+		if buf.IsEmpty() {
+			ph := i.Prompt.Placeholder
+			if i.Prompt.UseAlt {
+				ph = i.Prompt.AltPlaceholder
+			}
+			fmt.Printf(ColorGrey + ph + fmt.Sprintf(CursorLeftN, len(ph)) + ColorDefault)
+		}
+
+		r := i.Terminal.ReadRune()
+		if buf.IsEmpty() {
+			fmt.Printf(ClearToEOL)
+		}
+
+		if r == 0 { // io.EOF
+			break
+		}
+
+		if escex {
+			escex = false
+
+			switch r {
+			case KeyUp:
+				if i.History.Pos > 0 {
+					if i.History.Pos == i.History.Size() {
+						currentLineBuf = []rune(buf.String())
+					}
+					buf.Replace(i.History.Prev())
+				}
+			case KeyDown:
+				if i.History.Pos < i.History.Size() {
+					buf.Replace(i.History.Next())
+					if i.History.Pos == i.History.Size() {
+						buf.Replace(currentLineBuf)
+					}
+				}
+			case KeyLeft:
+				buf.MoveLeft()
+			case KeyRight:
+				buf.MoveRight()
+			case CharBracketedPaste:
+				bracketedPaste = true
+			case KeyDel:
+				if buf.Size() > 0 {
+					buf.Delete()
+				}
+				metaDel = true
+			case MetaStart:
+				buf.MoveToStart()
+			case MetaEnd:
+				buf.MoveToEnd()
+			default:
+				// skip any keys we don't know about
+				continue
+			}
+			continue
+		} else if esc {
+			esc = false
+
+			switch r {
+			case 'b':
+				buf.MoveLeftWord()
+			case 'f':
+				buf.MoveRightWord()
+			case CharEscapeEx:
+				escex = true
+			}
+			continue
+		}
+
+		switch r {
+		case CharBracketedPasteStart:
+			if bracketedPaste {
+				ignoreEnter = true
+			}
+		case CharEsc:
+			esc = true
+		case CharInterrupt:
+			return "", ErrInterrupt
+		case CharLineStart:
+			buf.MoveToStart()
+		case CharLineEnd:
+			buf.MoveToEnd()
+		case CharBackward:
+			buf.MoveLeft()
+		case CharForward:
+			buf.MoveRight()
+		case CharBackspace, CharCtrlH:
+			buf.Remove()
+		case CharTab:
+			// todo: convert back to real tabs
+			for cnt := 0; cnt < 8; cnt++ {
+				buf.Add(' ')
+			}
+		case CharDelete:
+			if buf.Size() > 0 {
+				buf.Delete()
+			} else {
+				return "", io.EOF
+			}
+		case CharKill:
+			buf.DeleteRemaining()
+		case CharCtrlU:
+			buf.DeleteBefore()
+		case CharCtrlL:
+			buf.ClearScreen()
+		case CharCtrlW:
+			buf.DeleteWord()
+		case CharEnter:
+			if !ignoreEnter {
+				output := buf.String()
+				if output != "" {
+					i.History.Add([]rune(output))
+				}
+				buf.MoveToEnd()
+				fmt.Println()
+				return output, nil
+			}
+			fallthrough
+		default:
+			if metaDel {
+				metaDel = false
+				continue
+			}
+			if r >= CharSpace || r == CharEnter {
+				buf.Add(r)
+			}
+		}
+	}
+	return "", nil
+}
+
+func (i *Instance) Close() error {
+	return i.Terminal.Close()
+}
+
+func (i *Instance) HistoryEnable() {
+	i.History.Enabled = true
+}
+
+func (i *Instance) HistoryDisable() {
+	i.History.Enabled = false
+}
+
+func NewTerminal() (*Terminal, error) {
+	t := &Terminal{
+		outchan: make(chan rune),
+	}
+
+	go t.ioloop()
+
+	return t, nil
+}
+
+func (t *Terminal) ioloop() {
+	buf := bufio.NewReader(os.Stdin)
+
+	for {
+		r, _, err := buf.ReadRune()
+		if err != nil {
+			break
+		}
+		t.outchan <- r
+		if r == 0 { // EOF
+			break
+		}
+	}
+
+}
+
+func (t *Terminal) ReadRune() rune {
+	r, ok := <-t.outchan
+	if !ok {
+		return rune(0)
+	}
+	return r
+}
+
+func (t *Terminal) Close() error {
+	close(t.outchan)
+	return nil
+}