1 files changed, 43 insertions, 0 deletions
diff --git a/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/impl/UserDataInterner.java b/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/impl/UserDataInterner.java
new file mode 100644
index 000000000000..f8da08d33198
--- /dev/null
+++ b/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/impl/UserDataInterner.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2000-2014 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.
+ */
+package com.intellij.openapi.vfs.newvfs.impl;
+
+import com.intellij.util.ConcurrencyUtil;
+import com.intellij.util.containers.ConcurrentWeakHashMap;
+import com.intellij.util.keyFMap.KeyFMap;
+import com.intellij.util.keyFMap.OneElementFMap;
+import org.jetbrains.annotations.NotNull;
+
+import java.nio.charset.Charset;
+
+/**
+ * @author peter
+ */
+class UserDataInterner {
+  private static final ConcurrentWeakHashMap<OneElementFMap, OneElementFMap> ourCache = new ConcurrentWeakHashMap<OneElementFMap, OneElementFMap>();
+
+  static KeyFMap internUserData(@NotNull KeyFMap map) {
+    if (map instanceof OneElementFMap && shouldIntern((OneElementFMap)map)) {
+      return ConcurrencyUtil.cacheOrGet(ourCache, (OneElementFMap)map, (OneElementFMap)map);
+    }
+    return map;
+  }
+
+  private static boolean shouldIntern(OneElementFMap map) {
+    Object value = map.getValue();
+    return value instanceof Enum || value instanceof Boolean || value instanceof Charset;
+  }
+}