From 7a5801c70c8b8010d8dd9516351cdb09e9fb8bfa Mon Sep 17 00:00:00 2001
From: Sergey Ignatov <sergey.ignatov@jetbrains.com>
Date: Wed, 29 May 2019 18:54:41 +0200
Subject: [PATCH] file util: don't load a traverser until it's needed

GitOrigin-RevId: 9e7ab9650008d8e0272bf178b73f6f4e173c274c
---
 .../src/com/intellij/openapi/util/io/FileUtil.java  | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/platform/util/src/com/intellij/openapi/util/io/FileUtil.java b/platform/util/src/com/intellij/openapi/util/io/FileUtil.java
index dc6e892094cf..4f05b86dcad9 100644
--- a/platform/util/src/com/intellij/openapi/util/io/FileUtil.java
+++ b/platform/util/src/com/intellij/openapi/util/io/FileUtil.java
@@ -7,7 +7,6 @@ import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.Condition;
 import com.intellij.openapi.util.SystemInfo;
 import com.intellij.openapi.util.text.StringUtil;
-import com.intellij.openapi.util.text.StringUtilRt;
 import com.intellij.util.*;
 import com.intellij.util.concurrency.FixedFuture;
 import com.intellij.util.containers.ContainerUtil;
@@ -1088,13 +1087,15 @@ public class FileUtil extends FileUtilRt {
     }
   }
 
-  @NotNull
-  public static JBTreeTraverser<File> fileTraverser(@Nullable File root) {
-    return FILE_TRAVERSER.withRoot(root);
+  private static class Lazy {
+    private static final JBTreeTraverser<File> FILE_TRAVERSER = JBTreeTraverser.from(
+      (Function<File, Iterable<File>>)file -> file == null ? Collections.emptySet() : JBIterable.of(file.listFiles()));
   }
 
-  private static final JBTreeTraverser<File> FILE_TRAVERSER = JBTreeTraverser.from(
-    (Function<File, Iterable<File>>)file -> file == null ? Collections.emptySet() : JBIterable.of(file.listFiles()));
+  @NotNull
+  public static JBTreeTraverser<File> fileTraverser(@Nullable File root) {
+    return Lazy.FILE_TRAVERSER.withRoot(root);
+  }
 
   public static boolean processFilesRecursively(@NotNull File root, @NotNull Processor<? super File> processor) {
     return fileTraverser(root).bfsTraversal().processEach(processor);