platform/indexing-api/src/com/intellij/psi/RefResolveService.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.psi;

import com.intellij.openapi.components.AbstractProjectComponent;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.vfs.VirtualFile;
import com.intellij.openapi.vfs.VirtualFileWithId;
import com.intellij.psi.search.GlobalSearchScope;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.Collection;

public abstract class RefResolveService extends AbstractProjectComponent {
  public RefResolveService(Project project) {
    super(project);
  }

  public static RefResolveService getInstance(Project project) {
    return project.getComponent(RefResolveService.class);
  }

  @Nullable("null means the service has not resolved all files and is not ready yet")
  public abstract int[] getBackwardIds(@NotNull VirtualFileWithId file);

  /**
   * @return subset of scope containing only files which reference the virtualFile
   */
  @NotNull
  public abstract GlobalSearchScope restrictByBackwardIds(@NotNull VirtualFile virtualFile, @NotNull GlobalSearchScope scope);

  /**
   * @return add files to the resolve queue. until all files from there are resolved, the service is in incomplete state and returns null from getBackwardIds()
   */
  public abstract boolean queue(@NotNull Collection<VirtualFile> files, Object reason);
}