content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you 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.apache.calcite.runtime;
  
  import org.locationtech.jts.geom.Geometry;
  import org.locationtech.jts.operation.union.UnaryUnionOp;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Used at run time by the ST_Union function.
   */
  public class UnionOperation {
  
    public List<Geometry> init() {
      return new ArrayList<>();
    }
  
    public List<Geometry> add(List<Geometry> accumulator, Geometry geometry) {
      accumulator.add(geometry);
      return accumulator;
    }
  
    public Geometry result(List<Geometry> accumulator) {
      return new UnaryUnionOp(accumulator).union();
    }
  }
  