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package readline
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const (
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	VIM_NORMAL = iota
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	VIM_INSERT
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	VIM_VISUAL
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)
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type opVim struct {
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	cfg     *Config
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	op      *Operation
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	vimMode int
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}
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func newVimMode(op *Operation) *opVim {
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	ov := &opVim{
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		cfg: op.cfg,
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		op:  op,
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	}
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	ov.SetVimMode(ov.cfg.VimMode)
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	return ov
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}
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func (o *opVim) SetVimMode(on bool) {
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	if o.cfg.VimMode && !on { // turn off
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		o.ExitVimMode()
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	}
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	o.cfg.VimMode = on
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	o.vimMode = VIM_INSERT
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}
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func (o *opVim) ExitVimMode() {
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	o.vimMode = VIM_INSERT
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}
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func (o *opVim) IsEnableVimMode() bool {
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	return o.cfg.VimMode
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}
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func (o *opVim) handleVimNormalMovement(r rune, readNext func() rune) (t rune, handled bool) {
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	rb := o.op.buf
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	handled = true
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	switch r {
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	case 'h':
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		t = CharBackward
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	case 'j':
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		t = CharNext
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	case 'k':
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		t = CharPrev
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	case 'l':
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		t = CharForward
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	case '0', '^':
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		rb.MoveToLineStart()
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	case '$':
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		rb.MoveToLineEnd()
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	case 'x':
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		rb.Delete()
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		if rb.IsCursorInEnd() {
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			rb.MoveBackward()
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		}
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	case 'r':
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		rb.Replace(readNext())
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	case 'd':
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		next := readNext()
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		switch next {
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		case 'd':
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			rb.Erase()
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		case 'w':
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			rb.DeleteWord()
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		case 'h':
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			rb.Backspace()
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		case 'l':
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			rb.Delete()
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		}
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	case 'p':
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		rb.Yank()
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	case 'b', 'B':
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		rb.MoveToPrevWord()
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	case 'w', 'W':
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		rb.MoveToNextWord()
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	case 'e', 'E':
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		rb.MoveToEndWord()
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	case 'f', 'F', 't', 'T':
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		next := readNext()
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		prevChar := r == 't' || r == 'T'
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		reverse := r == 'F' || r == 'T'
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		switch next {
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		case CharEsc:
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		default:
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			rb.MoveTo(next, prevChar, reverse)
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		}
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	default:
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		return r, false
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	}
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	return t, true
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}
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func (o *opVim) handleVimNormalEnterInsert(r rune, readNext func() rune) (t rune, handled bool) {
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	rb := o.op.buf
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	handled = true
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	switch r {
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	case 'i':
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	case 'I':
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		rb.MoveToLineStart()
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	case 'a':
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		rb.MoveForward()
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	case 'A':
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		rb.MoveToLineEnd()
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	case 's':
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		rb.Delete()
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	case 'S':
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		rb.Erase()
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	case 'c':
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		next := readNext()
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		switch next {
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		case 'c':
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			rb.Erase()
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		case 'w':
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			rb.DeleteWord()
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		case 'h':
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			rb.Backspace()
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		case 'l':
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			rb.Delete()
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		}
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	default:
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		return r, false
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	}
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	o.EnterVimInsertMode()
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	return
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}
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func (o *opVim) HandleVimNormal(r rune, readNext func() rune) (t rune) {
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	switch r {
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	case CharEnter, CharInterrupt:
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		o.ExitVimMode()
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		return r
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	}
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	if r, handled := o.handleVimNormalMovement(r, readNext); handled {
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		return r
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	}
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	if r, handled := o.handleVimNormalEnterInsert(r, readNext); handled {
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		return r
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	}
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	// invalid operation
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	o.op.t.Bell()
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	return 0
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}
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func (o *opVim) EnterVimInsertMode() {
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	o.vimMode = VIM_INSERT
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}
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func (o *opVim) ExitVimInsertMode() {
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	o.vimMode = VIM_NORMAL
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}
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func (o *opVim) HandleVim(r rune, readNext func() rune) rune {
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	if o.vimMode == VIM_NORMAL {
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		return o.HandleVimNormal(r, readNext)
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	}
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	if r == CharEsc {
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		o.ExitVimInsertMode()
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		return 0
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	}
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	switch o.vimMode {
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	case VIM_INSERT:
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		return r
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	case VIM_VISUAL:
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	}
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	return r
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}
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