From 477bdb3dc8cab1181630ddcf465831a1b2f87294 Mon Sep 17 00:00:00 2001
From: Zachary Yedidia <zyedidia@gmail.com>
Date: Tue, 28 Jan 2020 18:34:44 -0500
Subject: [PATCH] Empty highlighting for unknown filetypes

---
 internal/buffer/buffer.go    | 17 ++++++++++-------
 pkg/highlight/highlighter.go |  2 ++
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/internal/buffer/buffer.go b/internal/buffer/buffer.go
index 9e3cfcc9..e4af6be5 100644
--- a/internal/buffer/buffer.go
+++ b/internal/buffer/buffer.go
@@ -610,13 +610,16 @@ func (b *Buffer) UpdateRules() {
 	}
 
 	if b.Highlighter == nil || syntaxFile != "" {
-		if b.SyntaxDef != nil {
-			b.Settings["filetype"] = b.SyntaxDef.FileType
-			b.Highlighter = highlight.NewHighlighter(b.SyntaxDef)
-			if b.Settings["syntax"].(bool) {
-				b.Highlighter.HighlightStates(b)
-				b.Highlighter.HighlightMatches(b, 0, b.End().Y)
-			}
+		b.Settings["filetype"] = b.SyntaxDef.FileType
+	} else {
+		b.SyntaxDef = &highlight.EmptyDef
+	}
+
+	if b.SyntaxDef != nil {
+		b.Highlighter = highlight.NewHighlighter(b.SyntaxDef)
+		if b.Settings["syntax"].(bool) {
+			b.Highlighter.HighlightStates(b)
+			b.Highlighter.HighlightMatches(b, 0, b.End().Y)
 		}
 	}
 }
diff --git a/pkg/highlight/highlighter.go b/pkg/highlight/highlighter.go
index ec8eeaee..ae7c71b3 100644
--- a/pkg/highlight/highlighter.go
+++ b/pkg/highlight/highlighter.go
@@ -68,6 +68,8 @@ func combineLineMatch(src, dst LineMatch) LineMatch {
 // A State represents the region at the end of a line
 type State *region
 
+var EmptyDef = Def{nil, &rules{}}
+
 // LineStates is an interface for a buffer-like object which can also store the states and matches for every line
 type LineStates interface {
 	LineBytes(n int) []byte