HasEmbeddings.java

/*
 * Copyright © 2014 - 2021 Leipzig University (Database Research Group)
 *
 * 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 org.gradoop.flink.model.impl.operators.matching.transactional.function;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.java.functions.FunctionAnnotation;
import org.apache.flink.api.java.tuple.Tuple2;
import org.gradoop.common.model.impl.id.GradoopId;
import org.gradoop.flink.model.impl.operators.matching.transactional.algorithm.PatternMatchingAlgorithm;
import org.gradoop.flink.model.impl.operators.matching.transactional.tuples.GraphWithCandidates;

/**
 * Mapping function that applies a custom pattern matching algorithm to
 * a GraphWithCandidates, representing a graph, its elements and their
 * candidates. Returns true, iff the graph contained the pattern.
 */
@FunctionAnnotation.ForwardedFields("f0")
public class HasEmbeddings implements
  MapFunction<GraphWithCandidates, Tuple2<GradoopId, Boolean>> {

  /**
   * The pattern matching algorithm.
   */
  private PatternMatchingAlgorithm algorithm;

  /**
   * The query string, input fo the pattern matching algorithm.
   */
  private String query;

  /**
   * Reduce instantiations
   */
  private Tuple2<GradoopId, Boolean> reuseTuple;

  /**
   * Constructor
   *
   * @param algorithm the pattern matching algorithm
   * @param query     the query string
   */
  public HasEmbeddings(PatternMatchingAlgorithm algorithm, String query) {
    this.reuseTuple = new Tuple2<>();
    this.algorithm = algorithm;
    this.query = query;
  }

  @Override
  public Tuple2<GradoopId, Boolean> map(GraphWithCandidates transaction) throws
    Exception {
    this.reuseTuple.f0 = transaction.getGraphId();
    this.reuseTuple.f1 = algorithm.hasEmbedding(transaction, query);
    return reuseTuple;
  }
}