/*
 * Copyright 2020 Google LLC
 *
 * 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.google.cloud.solutions.datalineage.extractor;

import com.google.cloud.solutions.datalineage.model.LineageMessages.CompositeLineage;

/**
 * A No Operation extractor which returns empty collections.
 */
public final class NoOpExtractor extends LineageExtractor {

  private static final NoOpExtractor SINGLETON = new NoOpExtractor();

  private NoOpExtractor() {
    super("{}");
  }

  public static NoOpExtractor getInstance() {
    return SINGLETON;
  }

  @Override
  public CompositeLineage extract() {
    return CompositeLineage.getDefaultInstance();
  }
}
