Add barebones support for yank/paste (#120)

operation.go

@@ -226,6 +226,8 @@ func (o *Operation) ioloop() {
 			o.Refresh()
 		case MetaBackspace, CharCtrlW:
 			o.buf.BackEscapeWord()
+		case CharCtrlY:
+			o.buf.Yank()
 		case CharEnter, CharCtrlJ:
 			if o.IsSearchMode() {
 				o.ExitSearchMode(false)

runebuf.go

@@ -29,9 +29,15 @@ type RuneBuffer struct {
 
 	offset string
 
+	lastKill []rune
+
 	sync.Mutex
 }
 
+func (r* RuneBuffer) pushKill(text []rune) {
+	r.lastKill = append([]rune{}, text...)
+}
+
 func (r *RuneBuffer) OnWidthChange(newWidth int) {
 	r.Lock()
 	r.width = newWidth
@@ -187,6 +193,7 @@ func (r *RuneBuffer) Replace(ch rune) {
 func (r *RuneBuffer) Erase() {
 	r.Refresh(func() {
 		r.idx = 0
+		r.pushKill(r.buf[:])
 		r.buf = r.buf[:0]
 	})
 }
@@ -196,6 +203,7 @@ func (r *RuneBuffer) Delete() (success bool) {
 		if r.idx == len(r.buf) {
 			return
 		}
+		r.pushKill(r.buf[r.idx : r.idx+1])
 		r.buf = append(r.buf[:r.idx], r.buf[r.idx+1:]...)
 		success = true
 	})
@@ -212,6 +220,7 @@ func (r *RuneBuffer) DeleteWord() {
 	}
 	for i := init + 1; i < len(r.buf); i++ {
 		if !IsWordBreak(r.buf[i]) && IsWordBreak(r.buf[i-1]) {
+			r.pushKill(r.buf[r.idx:i-1])
 			r.Refresh(func() {
 				r.buf = append(r.buf[:r.idx], r.buf[i-1:]...)
 			})
@@ -247,6 +256,7 @@ func (r *RuneBuffer) KillFront() {
 		}
 
 		length := len(r.buf) - r.idx
+		r.pushKill(r.buf[:r.idx])
 		copy(r.buf[:length], r.buf[r.idx:])
 		r.idx = 0
 		r.buf = r.buf[:length]
@@ -255,6 +265,7 @@ func (r *RuneBuffer) KillFront() {
 
 func (r *RuneBuffer) Kill() {
 	r.Refresh(func() {
+		r.pushKill(r.buf[r.idx:])
 		r.buf = r.buf[:r.idx]
 	})
 }
@@ -321,6 +332,7 @@ func (r *RuneBuffer) BackEscapeWord() {
 		}
 		for i := r.idx - 1; i > 0; i-- {
 			if !IsWordBreak(r.buf[i]) && IsWordBreak(r.buf[i-1]) {
+				r.pushKill(r.buf[i:r.idx])
 				r.buf = append(r.buf[:i], r.buf[r.idx:]...)
 				r.idx = i
 				return
@@ -332,6 +344,20 @@ func (r *RuneBuffer) BackEscapeWord() {
 	})
 }
 
+func (r *RuneBuffer) Yank() {
+	if len(r.lastKill) == 0 {
+		return
+	}
+	r.Refresh(func() {
+		buf := make([]rune, 0, len(r.buf) + len(r.lastKill))
+		buf = append(buf, r.buf[:r.idx]...)
+		buf = append(buf, r.lastKill...)
+		buf = append(buf, r.buf[r.idx:]...)
+		r.buf = buf
+		r.idx += len(r.lastKill)
+	})
+}
+
 func (r *RuneBuffer) Backspace() {
 	r.Refresh(func() {
 		if r.idx == 0 {

utils.go

@@ -38,6 +38,7 @@ const (
 	CharTranspose = 20
 	CharCtrlU     = 21
 	CharCtrlW     = 23
+	CharCtrlY     = 25
 	CharCtrlZ     = 26
 	CharEsc       = 27
 	CharEscapeEx  = 91

vim.go

@@ -72,6 +72,8 @@ func (o *opVim) handleVimNormalMovement(r rune, readNext func() rune) (t rune, h
 		case 'l':
 			rb.Delete()
 		}
+	case 'p':
+		rb.Yank()
 	case 'b', 'B':
 		rb.MoveToPrevWord()
 	case 'w', 'W':