perf(cellbuf): optimize Equal methods using pointers and int comparison

cellbuf/cell.go

@@ -52,15 +52,15 @@ func (c *Cell) Equal(o *Cell) bool {
 		c.Width == o.Width &&
 		c.Rune == o.Rune &&
 		runesEqual(c.Comb, o.Comb) &&
-		c.Style.Equal(o.Style) &&
-		c.Link.Equal(o.Link)
+		c.Style.Equal(&o.Style) &&
+		c.Link.Equal(&o.Link)
 }
 
 // Empty returns whether the cell is empty.
 func (c Cell) Empty() bool {
-	return c.Rune == 0 &&
+	return c.Width == 0 &&
+		c.Rune == 0 &&
 		len(c.Comb) == 0 &&
-		c.Width == 0 &&
 		c.Style.Empty() &&
 		c.Link.Empty()
 }
@@ -114,8 +114,8 @@ func (h *Link) Reset() {
 }
 
 // Equal returns whether the hyperlink is equal to the other hyperlink.
-func (h Link) Equal(o Link) bool {
-	return h == o
+func (h *Link) Equal(o *Link) bool {
+	return o != nil && h.URL == o.URL && h.URLID == o.URLID
 }
 
 // Empty returns whether the hyperlink is empty.
@@ -320,12 +320,12 @@ func (s Style) DiffSequence(o Style) string {
 }
 
 // Equal returns true if the style is equal to the other style.
-func (s Style) Equal(o Style) bool {
-	return colorEqual(s.Fg, o.Fg) &&
+func (s *Style) Equal(o *Style) bool {
+	return s.Attrs == o.Attrs &&
+		s.UlStyle == o.UlStyle &&
+		colorEqual(s.Fg, o.Fg) &&
 		colorEqual(s.Bg, o.Bg) &&
-		colorEqual(s.Ul, o.Ul) &&
-		s.Attrs == o.Attrs &&
-		s.UlStyle == o.UlStyle
+		colorEqual(s.Ul, o.Ul)
 }
 
 func colorEqual(c, o ansi.Color) bool {

cellbuf/screen.go

@@ -63,10 +63,6 @@ func relativeCursorMove(s *Screen, fx, fy, tx, ty int, overwrite, useTabs bool)
 			if cuu := ansi.CursorUp(n); yseq == "" || len(cuu) < len(yseq) {
 				yseq = cuu
 			}
-			if n == 1 && fy-1 > 0 {
-				// TODO: Ensure we're not unintentionally scrolling the screen up.
-				yseq = ansi.ReverseIndex
-			}
 		}
 
 		seq.WriteString(yseq)
@@ -117,9 +113,9 @@ func relativeCursorMove(s *Screen, fx, fy, tx, ty int, overwrite, useTabs bool)
 			if overwrite && ty >= 0 {
 				for i := 0; i < n; i++ {
 					cell := s.newbuf.Cell(fx+i, ty)
-					if cell != nil {
+					if cell != nil && cell.Width > 0 {
 						i += cell.Width - 1
-						if !cell.Style.Equal(s.cur.Style) || !cell.Link.Equal(s.cur.Link) {
+						if !cell.Style.Equal(&s.cur.Style) || !cell.Link.Equal(&s.cur.Link) {
 							overwrite = false
 							break
 						}
@@ -130,7 +126,7 @@ func relativeCursorMove(s *Screen, fx, fy, tx, ty int, overwrite, useTabs bool)
 			if overwrite && ty >= 0 {
 				for i := 0; i < n; i++ {
 					cell := s.newbuf.Cell(fx+i, ty)
-					if cell != nil {
+					if cell != nil && cell.Width > 0 {
 						ovw += cell.String()
 						i += cell.Width - 1
 					} else {
@@ -623,15 +619,15 @@ func (s *Screen) updatePen(cell *Cell) {
 		link = ConvertLink(link, s.opts.Profile)
 	}
 
-	if !style.Equal(s.cur.Style) {
+	if !style.Equal(&s.cur.Style) {
 		seq := style.DiffSequence(s.cur.Style)
 		if style.Empty() && len(seq) > len(ansi.ResetStyle) {
 			seq = ansi.ResetStyle
 		}
 		s.buf.WriteString(seq) //nolint:errcheck
 		s.cur.Style = style
 	}
-	if !link.Equal(s.cur.Link) {
+	if !link.Equal(&s.cur.Link) {
 		s.buf.WriteString(ansi.SetHyperlink(link.URL, link.URLID)) //nolint:errcheck
 		s.cur.Link = link
 	}