/*
 * Copyright 2000-2009 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.util;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * @author cdr
 */
public interface UserDataHolderEx extends UserDataHolder {
  /**
   * @return written value
   */
  @NotNull
  <T> T putUserDataIfAbsent(@NotNull Key<T> key, @NotNull T value);

  /**
   * Replaces (atomically) old value in the map with the new one
   * @return true if old value got replaced, false otherwise
   * @see java.util.concurrent.ConcurrentMap#replace(Object, Object, Object)
   */
  <T> boolean replace(@NotNull Key<T> key, @Nullable T oldValue, @Nullable T newValue);
}
