From 58a28122aa8e88538eb4c6eae9800cced98188ed Mon Sep 17 00:00:00 2001
From: Aleksey Pivovarov <AMPivovarov@gmail.com>
Date: Tue, 24 Sep 2019 19:02:52 +0300
Subject: [PATCH] lst: optimization - do not compare CharSequences if they're
 identical

This is the case for `LineStatusTrackerBase`.

GitOrigin-RevId: 696edac43b83725b44bdc1cef559453085e3dec8
---
 .../com/intellij/openapi/vcs/ex/DocumentTracker.kt    | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/platform/diff-impl/src/com/intellij/openapi/vcs/ex/DocumentTracker.kt b/platform/diff-impl/src/com/intellij/openapi/vcs/ex/DocumentTracker.kt
index f0393c0a656f..3b93767670a2 100644
--- a/platform/diff-impl/src/com/intellij/openapi/vcs/ex/DocumentTracker.kt
+++ b/platform/diff-impl/src/com/intellij/openapi/vcs/ex/DocumentTracker.kt
@@ -47,10 +47,13 @@ class DocumentTracker : Disposable {
     this.document2 = document2
     this.handler = handler
 
-    val changes = compareLines(document1.immutableCharSequence,
-                               document2.immutableCharSequence,
-                               document1.lineOffsets,
-                               document2.lineOffsets).iterateChanges().toList()
+    val changes = when {
+      document1.immutableCharSequence === document2.immutableCharSequence -> emptyList()
+      else -> compareLines(document1.immutableCharSequence,
+                           document2.immutableCharSequence,
+                           document1.lineOffsets,
+                           document2.lineOffsets).iterateChanges().toList()
+    }
     tracker = LineTracker(this.handler, changes)
 
     val application = ApplicationManager.getApplication()