AdoptEmptyPaths.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.single.cypher.operators.expand.functions;
import org.apache.flink.api.common.functions.RichFlatMapFunction;
import org.apache.flink.util.Collector;
import org.gradoop.flink.model.impl.operators.matching.single.cypher.pojos.Embedding;
import static java.util.Objects.deepEquals;
/**
* Input embeddings are extended by an empty path and an additional entry which equals the entry at
* the expand column. This is done to ensure equally sized embeddings in the case of Expand
* operations with lower bound 0
*/
public class AdoptEmptyPaths extends RichFlatMapFunction<Embedding, Embedding> {
/**
* The column the expansion starts at
*/
private final int expandColumn;
/**
* The column the expanded paths should end at
*/
private final int closingColumn;
/**
* Creates a new UDF instance
* @param expandColumn column the expantion starts at
* @param closingColumn column the expanded path should end at
*/
public AdoptEmptyPaths(int expandColumn, int closingColumn) {
this.expandColumn = expandColumn;
this.closingColumn = closingColumn;
}
@Override
public void flatMap(Embedding value, Collector<Embedding> out) {
if (closingColumn >= 0 &&
!deepEquals(value.getRawId(expandColumn), value.getRawId(closingColumn))) {
return;
}
value.add();
value.add(value.getId(expandColumn));
out.collect(value);
}
}