From cfb5af3e40d83774f994f5ec0de5f2bcb9c0b038 Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Tue, 24 May 2016 12:35:28 +0200
Subject: [PATCH] LexerEditorHighlighter: do nothing in setText if the text is
 identical to the previous one

---
 .../ex/util/LayeredLexerEditorHighlighter.java  | 17 ++++++++---------
 .../editor/ex/util/LexerEditorHighlighter.java  | 13 ++++++++++---
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/platform/editor-ui-ex/src/com/intellij/openapi/editor/ex/util/LayeredLexerEditorHighlighter.java b/platform/editor-ui-ex/src/com/intellij/openapi/editor/ex/util/LayeredLexerEditorHighlighter.java
index df600d3963ef..8af290897cd1 100644
--- a/platform/editor-ui-ex/src/com/intellij/openapi/editor/ex/util/LayeredLexerEditorHighlighter.java
+++ b/platform/editor-ui-ex/src/com/intellij/openapi/editor/ex/util/LayeredLexerEditorHighlighter.java
@@ -47,7 +47,6 @@ import java.util.*;
 public class LayeredLexerEditorHighlighter extends LexerEditorHighlighter {
   private final Map<IElementType, LayerDescriptor> myTokensToLayer = new HashMap<>();
   private final Map<LayerDescriptor, Mapper> myLayerBuffers = new HashMap<>();
-  private CharSequence myText;
 
   public LayeredLexerEditorHighlighter(@NotNull SyntaxHighlighter highlighter, @NotNull EditorColorsScheme scheme) {
     super(highlighter, scheme);
@@ -120,7 +119,6 @@ public class LayeredLexerEditorHighlighter extends LexerEditorHighlighter {
     // do NOT synchronize before updateLayers due to deadlock with PsiLock
     updateLayers();
 
-    myText = text;
     super.setText(text);
   }
 
@@ -158,12 +156,11 @@ public class LayeredLexerEditorHighlighter extends LexerEditorHighlighter {
   @Override
   public void documentChanged(DocumentEvent e) {
     // do NOT synchronize before updateLayers due to deadlock with PsiLock
-    final boolean b = updateLayers();
+    boolean changed = updateLayers();
 
     synchronized (this) {
-      myText = e.getDocument().getCharsSequence();
-      if (b) {
-        setText(myText);
+      if (changed) {
+        setText(e.getDocument().getImmutableCharSequence());
       }
       else {
         super.documentChanged(e);
@@ -175,11 +172,13 @@ public class LayeredLexerEditorHighlighter extends LexerEditorHighlighter {
   @Override
   public HighlighterIterator createIterator(int startOffset) {
     // do NOT synchronize before updateLayers due to deadlock with PsiLock
-    final boolean b = updateLayers();
+    final boolean changed = updateLayers();
 
     synchronized (this) {
-      if (b) {
-        setText(myText);
+      if (changed) {
+        CharSequence text = myText;
+        myText = null;
+        setText(text);
       }
       return new LayeredHighlighterIteratorImpl(startOffset);
     }
diff --git a/platform/editor-ui-ex/src/com/intellij/openapi/editor/ex/util/LexerEditorHighlighter.java b/platform/editor-ui-ex/src/com/intellij/openapi/editor/ex/util/LexerEditorHighlighter.java
index a31eacbdfc62..baaf4c21183a 100644
--- a/platform/editor-ui-ex/src/com/intellij/openapi/editor/ex/util/LexerEditorHighlighter.java
+++ b/platform/editor-ui-ex/src/com/intellij/openapi/editor/ex/util/LexerEditorHighlighter.java
@@ -37,6 +37,7 @@ import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.Comparing;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.util.ArrayUtil;
+import com.intellij.util.text.ImmutableCharSequence;
 import com.intellij.util.text.ImmutableText;
 import com.intellij.util.ui.UIUtil;
 import org.jetbrains.annotations.NotNull;
@@ -54,6 +55,7 @@ public class LexerEditorHighlighter implements EditorHighlighter, PrioritizedDoc
   private final SyntaxHighlighter myHighlighter;
   private EditorColorsScheme myScheme;
   private final int myInitialState;
+  protected CharSequence myText;
 
   public LexerEditorHighlighter(@NotNull SyntaxHighlighter highlighter, @NotNull EditorColorsScheme scheme) {
     myScheme = scheme;
@@ -112,7 +114,7 @@ public class LexerEditorHighlighter implements EditorHighlighter, PrioritizedDoc
         if(document instanceof DocumentEx && ((DocumentEx)document).isInBulkUpdate()) {
           ((DocumentEx)document).setInBulkUpdate(false); // bulk mode failed
         }
-        doSetText(document.getCharsSequence());
+        doSetText(document.getImmutableCharSequence());
       }
 
       final int latestValidOffset = mySegments.getLastValidOffset();
@@ -147,18 +149,20 @@ public class LexerEditorHighlighter implements EditorHighlighter, PrioritizedDoc
   public synchronized void documentChanged(DocumentEvent e) {
     try {
       final Document document = e.getDocument();
+      CharSequence text = document.getImmutableCharSequence();
 
       if (document instanceof DocumentEx && ((DocumentEx)document).isInBulkUpdate()) {
+        myText = null;
         mySegments.removeAll();
         return;
       }
 
       if(mySegments.getSegmentCount() == 0) {
-        setText(document.getCharsSequence());
+        setText(text);
         return;
       }
 
-      CharSequence text = document.getCharsSequence();
+      myText = text;
       int oldStartOffset = e.getOffset();
 
       final int segmentIndex = mySegments.findSegmentIndex(oldStartOffset) - 2;
@@ -312,6 +316,9 @@ public class LexerEditorHighlighter implements EditorHighlighter, PrioritizedDoc
   }
 
   private void doSetText(final CharSequence text) {
+    if (Comparing.equal(myText, text)) return;
+    myText = ImmutableCharSequence.asImmutable(text);
+
     final TokenProcessor processor = createTokenProcessor(0);
     final int textLength = text.length();
     myLexer.start(text, 0, textLength, myInitialState);