highlighter: Fix last open racy access in the *Highlight*() functions

Otherwise it's possible that `*Highlight*()` functions called from the async
initial highlighting can be interrupted by the main goroutine, which then
changes the already set and furthermore used `h.lastRegion`. The resulting
last region respective set state isn't reliable any longer then.

pkg/highlight/highlighter.go

@@ -315,6 +315,11 @@ func (h *Highlighter) HighlightStates(input LineStates) {
  line := input.LineBytes(i)
  // highlights := make(LineMatch)
 
+ h.lastRegion = nil
+ if i > 0 {
+ h.lastRegion = input.State(i - 1)
+ }
+
  if i == 0 || h.lastRegion == nil {
  h.highlightEmptyRegion(nil, 0, true, i, line, true)
  } else {
@@ -332,6 +337,14 @@ func (h *Highlighter) HighlightStates(input LineStates) {
 // It sets all other matches in the buffer to nil to conserve memory
 // This assumes that all the states are set correctly
 func (h *Highlighter) HighlightMatches(input LineStates, startline, endline int) {
+ var curState *region
+ if startline > 0 {
+ input.Lock()
+ if startline-1 < input.LinesNum() {
+ curState = input.State(startline - 1)
+ }
+ input.Unlock()
+ }
  for i := startline; i <= endline; i++ {
  input.Lock()
  if i >= input.LinesNum() {
@@ -343,11 +356,13 @@ func (h *Highlighter) HighlightMatches(input LineStates, startline, endline int)
  highlights := make(LineMatch)
 
  var match LineMatch
- if i == 0 || input.State(i-1) == nil {
+ h.lastRegion = curState
+ if i == 0 || h.lastRegion == nil {
  match = h.highlightEmptyRegion(highlights, 0, true, i, line, false)
  } else {
- match = h.highlightRegion(highlights, 0, true, i, line, input.State(i-1), false)
+ match = h.highlightRegion(highlights, 0, true, i, line, h.lastRegion, false)
  }
+ curState = h.lastRegion
 
  input.SetMatch(i, match)
  input.Unlock()
@@ -360,11 +375,11 @@ func (h *Highlighter) HighlightMatches(input LineStates, startline, endline int)
 func (h *Highlighter) ReHighlightStates(input LineStates, startline int) int {
  // lines := input.LineData()
 
- h.lastRegion = nil
+ var curState *region
  if startline > 0 {
  input.Lock()
  if startline-1 < input.LinesNum() {
- h.lastRegion = input.State(startline - 1)
+ curState = input.State(startline - 1)
  }
  input.Unlock()
  }
@@ -379,12 +394,13 @@ func (h *Highlighter) ReHighlightStates(input LineStates, startline int) int {
  // highlights := make(LineMatch)
 
  // var match LineMatch
+ h.lastRegion = curState
  if i == 0 || h.lastRegion == nil {
  h.highlightEmptyRegion(nil, 0, true, i, line, true)
  } else {
  h.highlightRegion(nil, 0, true, i, line, h.lastRegion, true)
  }
- curState := h.lastRegion
+ curState = h.lastRegion
  lastState := input.State(i)
 
  input.SetState(i, curState)