Don't rehighlight if there are no modifications

internal/buffer/buffer.go

@@ -278,7 +278,7 @@ func NewBuffer(r io.Reader, size int64, path string, startcursor Loc, btype BufT
 		screen.TermMessage(err)
 	}
 
-	b.Modifications = make([]Loc, 10)
+	b.Modifications = make([]Loc, 0, 10)
 
 	OpenBuffers = append(OpenBuffers, b)
 
@@ -615,6 +615,7 @@ func (b *Buffer) UpdateRules() {
 			b.Highlighter = highlight.NewHighlighter(b.SyntaxDef)
 			if b.Settings["syntax"].(bool) {
 				b.Highlighter.HighlightStates(b)
+				b.Highlighter.HighlightMatches(b, 0, b.End().Y)
 			}
 		}
 	}

internal/display/bufwindow.go

@@ -358,6 +358,10 @@ func (w *BufWindow) showCursor(x, y int, main bool) {
 func (w *BufWindow) displayBuffer() {
 	b := w.Buf
 
+	if w.Height <= 0 || w.Width <= 0 {
+		return
+	}
+
 	hasMessage := len(b.Messages) > 0
 	bufHeight := w.Height
 	if w.drawStatus {
@@ -371,16 +375,12 @@ func (w *BufWindow) displayBuffer() {
 
 	if b.Settings["syntax"].(bool) && b.SyntaxDef != nil {
 		for _, r := range b.Modifications {
+			final := -1
 			for i := r.X; i <= r.Y; i++ {
-				if i > 0 && b.Rehighlight(i-1) {
-					b.Highlighter.ReHighlightLine(b, i-1)
-					b.SetRehighlight(i-1, false)
-				}
-
-				b.Highlighter.ReHighlightStates(b, i)
+				final = util.Max(b.Highlighter.ReHighlightStates(b, i), final)
 			}
+			b.Highlighter.HighlightMatches(b, r.X, final+1)
 		}
-		b.Highlighter.HighlightMatches(b, w.StartLine, w.StartLine+bufHeight)
 		b.ClearModifications()
 	}
 

pkg/highlight/highlighter.go

@@ -358,8 +358,9 @@ func (h *Highlighter) HighlightMatches(input LineStates, startline, endline int)
 }
 
 // ReHighlightStates will scan down from `startline` and set the appropriate end of line state
-// for each line until it comes across the same state in two consecutive lines
-func (h *Highlighter) ReHighlightStates(input LineStates, startline int) {
+// for each line until it comes across a line whose state does not change
+// returns the number of the final line
+func (h *Highlighter) ReHighlightStates(input LineStates, startline int) int {
 	// lines := input.LineData()
 
 	h.lastRegion = nil
@@ -382,9 +383,11 @@ func (h *Highlighter) ReHighlightStates(input LineStates, startline int) {
 		input.SetState(i, curState)
 
 		if curState == lastState {
-			break
+			return i
 		}
 	}
+
+	return input.LinesNum() - 1
 }
 
 // ReHighlightLine will rehighlight the state and match for a single line