platform/structure-view-api/src/com/intellij/ide/util/treeView/AbstractTreeStructure.java

/*
 * 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.ide.util.treeView;

import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.ActionCallback;
import com.intellij.openapi.util.AsyncResult;
import com.intellij.psi.PsiDocumentManager;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

public abstract class AbstractTreeStructure {
  public abstract Object getRootElement();
  public abstract Object[] getChildElements(Object element);
  @Nullable
  public abstract Object getParentElement(Object element);

  @NotNull
  public abstract NodeDescriptor createDescriptor(Object element, NodeDescriptor parentDescriptor);

  public abstract void commit();
  public abstract boolean hasSomethingToCommit();

  @NotNull
  public static ActionCallback asyncCommitDocuments(@NotNull Project project) {
    if (project.isDisposed()) return new ActionCallback.Done();
    PsiDocumentManager documentManager = PsiDocumentManager.getInstance(project);
    if (!documentManager.hasUncommitedDocuments()) {
      return new ActionCallback.Done();
    }
    final ActionCallback callback = new ActionCallback();
    documentManager.performWhenAllCommitted(callback.createSetDoneRunnable());
    return callback;
  }

  /**
   * @return callback which is set to {@link ActionCallback#setDone()} when the tree structure is committed.
   * By default it just calls {@link #commit()} synchronously but it is desirable to override it
   * to provide asynchronous commit to the tree structure to make it more responsible.
   * E.g. when you should commit all documents during the {@link #commit()},
   * you can use {@link #asyncCommitDocuments(Project)} to do it asynchronously.
   */
  @NotNull
  public ActionCallback asyncCommit() {
    if (hasSomethingToCommit()) commit();
    return new ActionCallback.Done();
  }

  public boolean isToBuildChildrenInBackground(Object element){
    return false;
  }
  
  public boolean isValid(Object element) {
    return true;
  }

  public boolean isAlwaysLeaf(Object element) {
    return false;
  }

  public AsyncResult<Object> revalidateElement(Object element) {
    return new AsyncResult.Done<Object>(element);
  }
}