StateStorage.java

/*
 * 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.
 */
package com.intellij.openapi.components;

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

import java.io.IOException;
import java.util.Set;

public interface StateStorage {
  /**
   * You can call this method only once.
   * If state exists and not archived - not-null result.
   * If doesn't exists or archived - null result.
   */
  @Nullable
  <T> T getState(@Nullable Object component, @NotNull String componentName, @NotNull Class<T> stateClass, @Nullable T mergeInto, boolean reload);

  boolean hasState(@NotNull String componentName, boolean reloadData);

  @Nullable
  ExternalizationSession startExternalization();

  /**
   * Get changed component names
   */
  void analyzeExternalChangesAndUpdateIfNeed(@NotNull Set<String> componentNames);

  @NotNull
  default StateStorageChooserEx.Resolution getResolution(@NotNull PersistentStateComponent<?> component, @NotNull StateStorageOperation operation) {
    return StateStorageChooserEx.Resolution.DO;
  }

  interface ExternalizationSession {
    default void setState(@Nullable Object component, @NotNull String componentName, @NotNull Object state) {
    }

    /**
     * return null if nothing to save
     */
    @Nullable
    SaveSession createSaveSession();
  }

  interface SaveSession {
    void save() throws IOException;
  }
}