From c0fc89b71542e67fb4bc5b96f1bb23f389e7b0cc Mon Sep 17 00:00:00 2001
From: Vladimir Krivosheev <vladimir.krivosheev@jetbrains.com>
Date: Wed, 22 Aug 2018 17:49:24 +0200
Subject: [PATCH] avoid AttributeList creation if no attributes

---
 platform/util/src/org/jdom/JDOMInterner.java | 27 ++++++++------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/platform/util/src/org/jdom/JDOMInterner.java b/platform/util/src/org/jdom/JDOMInterner.java
index 0abee6cfbba6..550b898f1fcc 100644
--- a/platform/util/src/org/jdom/JDOMInterner.java
+++ b/platform/util/src/org/jdom/JDOMInterner.java
@@ -1,16 +1,4 @@
-// Copyright 2000-2017 JetBrains s.r.o.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
+// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jdom;
 
 import com.intellij.openapi.util.Comparing;
@@ -19,6 +7,7 @@ import com.intellij.util.containers.StringInterner;
 import gnu.trove.TObjectHashingStrategy;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.Collections;
 import java.util.List;
 
 public class JDOMInterner {
@@ -70,7 +59,7 @@ public class JDOMInterner {
   });
 
   private static int computeAttributesHashCode(Element e) {
-    List<Attribute> attributes = e.getAttributes();
+    List<Attribute> attributes = getAttributes(e);
     if (attributes instanceof ImmutableSameTypeAttributeList) {
       return attributes.hashCode();
     }
@@ -81,6 +70,12 @@ public class JDOMInterner {
     return result;
   }
 
+  @NotNull
+  private static List<Attribute> getAttributes(@NotNull Element e) {
+    // avoid AttributeList creation if no attributes
+    return e.hasAttributes() ? e.getAttributes() : Collections.<Attribute>emptyList();
+  }
+
   private static boolean attributesEqual(Element o1, Element o2) {
     if (o1 instanceof ImmutableElement)  {
       return ((ImmutableElement)o1).attributesEqual(o2);
@@ -88,8 +83,8 @@ public class JDOMInterner {
     if (o2 instanceof ImmutableElement)  {
       return ((ImmutableElement)o2).attributesEqual(o1);
     }
-    List<Attribute> a1 = o1.getAttributes();
-    List<Attribute> a2 = o2.getAttributes();
+    List<Attribute> a1 = getAttributes(o1);
+    List<Attribute> a2 = getAttributes(o2);
     if (a1.size() != a2.size()) return false;
     for (int i=0; i<a1.size(); i++) {
       Attribute attr1 = a1.get(i);