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A packaging of the IntelliJ Community Edition util library. This is release number 1 of trunk branch 142.
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/*
 * Copyright 2000-2015 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 com.intellij.util.concurrency.AtomicFieldUpdater;
import com.intellij.util.keyFMap.KeyFMap;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.jetbrains.annotations.TestOnly;

public class UserDataHolderBase implements UserDataHolderEx, Cloneable {
  private static final Key COPYABLE_USER_MAP_KEY = Key.create("COPYABLE_USER_MAP_KEY");

  /**
   * Concurrent writes to this field are via CASes only, using the {@link #updater}
   */
  @NotNull
  private volatile KeyFMap myUserMap = KeyFMap.EMPTY_MAP;

  @Override
  protected Object clone() {
    try {
      UserDataHolderBase clone = (UserDataHolderBase)super.clone();
      clone.setUserMap(KeyFMap.EMPTY_MAP);
      copyCopyableDataTo(clone);
      return clone;
    }
    catch (CloneNotSupportedException e) {
      throw new RuntimeException(e);
    }
  }

  @TestOnly
  public String getUserDataString() {
    final KeyFMap userMap = getUserMap();
    final KeyFMap copyableMap = getUserData(COPYABLE_USER_MAP_KEY);
    return userMap + (copyableMap == null ? "" : copyableMap.toString());
  }

  public void copyUserDataTo(@NotNull UserDataHolderBase other) {
    other.setUserMap(getUserMap());
  }

  @Override
  public  T getUserData(@NotNull Key key) {
    //noinspection unchecked
    return getUserMap().get(key);
  }

  @NotNull
  protected KeyFMap getUserMap() {
    return myUserMap;
  }

  @Override
  public  void putUserData(@NotNull Key key, @Nullable T value) {
    while (true) {
      KeyFMap map = getUserMap();
      KeyFMap newMap = value == null ? map.minus(key) : map.plus(key, value);
      if (newMap == map || changeUserMap(map, newMap)) {
        break;
      }
    }
  }

  protected boolean changeUserMap(KeyFMap oldMap, KeyFMap newMap) {
    return updater.compareAndSet(this, oldMap, newMap);
  }

  public  T getCopyableUserData(@NotNull Key key) {
    KeyFMap map = getUserData(COPYABLE_USER_MAP_KEY);
    //noinspection unchecked,ConstantConditions
    return map == null ? null : map.get(key);
  }

  public  void putCopyableUserData(@NotNull Key key, T value) {
    while (true) {
      KeyFMap map = getUserMap();
      KeyFMap copyableMap = map.get(COPYABLE_USER_MAP_KEY);
      if (copyableMap == null) {
        copyableMap = KeyFMap.EMPTY_MAP;
      }
      KeyFMap newCopyableMap = value == null ? copyableMap.minus(key) : copyableMap.plus(key, value);
      KeyFMap newMap = newCopyableMap.isEmpty() ? map.minus(COPYABLE_USER_MAP_KEY) : map.plus(COPYABLE_USER_MAP_KEY, newCopyableMap);
      if (newMap == map || changeUserMap(map, newMap)) {
        return;
      }
    }
  }

  @Override
  public  boolean replace(@NotNull Key key, @Nullable T oldValue, @Nullable T newValue) {
    while (true) {
      KeyFMap map = getUserMap();
      if (map.get(key) != oldValue) {
        return false;
      }
      KeyFMap newMap = newValue == null ? map.minus(key) : map.plus(key, newValue);
      if (newMap == map || changeUserMap(map, newMap)) {
        return true;
      }
    }
  }
                                                            
  @Override
  @NotNull
  public  T putUserDataIfAbsent(@NotNull final Key key, @NotNull final T value) {
    while (true) {
      KeyFMap map = getUserMap();
      T oldValue = map.get(key);
      if (oldValue != null) {
        return oldValue;
      }
      KeyFMap newMap = map.plus(key, value);
      if (newMap == map || changeUserMap(map, newMap)) {
        return value;
      }
    }
  }

  public void copyCopyableDataTo(@NotNull UserDataHolderBase clone) {
    clone.putUserData(COPYABLE_USER_MAP_KEY, getUserData(COPYABLE_USER_MAP_KEY));
  }

  protected void clearUserData() {
    setUserMap(KeyFMap.EMPTY_MAP);
  }

  protected void setUserMap(@NotNull KeyFMap map) {
    myUserMap = map;
  }

  public boolean isUserDataEmpty() {
    return getUserMap().isEmpty();
  }

  private static final AtomicFieldUpdater updater = AtomicFieldUpdater.forFieldOfType(UserDataHolderBase.class, KeyFMap.class);
}