    001/*
    002 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
    003 *
    004 * Project and contact information: http://www.cascading.org/
    005 *
    006 * This file is part of the Cascading project.
    007 *
    008 * Licensed under the Apache License, Version 2.0 (the "License");
    009 * you may not use this file except in compliance with the License.
    010 * You may obtain a copy of the License at
    011 *
    012 *     http://www.apache.org/licenses/LICENSE-2.0
    013 *
    014 * Unless required by applicable law or agreed to in writing, software
    015 * distributed under the License is distributed on an "AS IS" BASIS,
    016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    017 * See the License for the specific language governing permissions and
    018 * limitations under the License.
    019 */
    020
    021package cascading.flow.planner.iso.transformer;
    022
    023import java.util.Set;
    024
    025import cascading.flow.FlowElement;
    026import cascading.flow.planner.PlannerContext;
    027import cascading.flow.planner.graph.ElementGraph;
    028import cascading.flow.planner.graph.ElementGraphs;
    029import cascading.flow.planner.graph.ElementMultiGraph;
    030import cascading.flow.planner.iso.expression.ElementCapture;
    031import cascading.flow.planner.iso.expression.ExpressionGraph;
    032import cascading.flow.planner.iso.finder.Match;
    033
    034/**
    035 *
    036 */
    037public class ContractedTransformer extends RecursiveGraphTransformer<ElementGraph>
    038  {
    039  public ContractedTransformer( ExpressionGraph expression )
    040    {
    041    super( expression );
    042    }
    043
    044  @Override
    045  public Transformed<ElementGraph> transform( PlannerContext plannerContext, ElementGraph rootGraph )
    046    {
    047    return super.transform( plannerContext, new ElementMultiGraph( rootGraph ) );
    048    }
    049
    050  @Override
    051  protected boolean transformGraphInPlaceUsing( Transformed<ElementGraph> transformed, ElementGraph graph, Match match )
    052    {
    053    Set<FlowElement> remove = match.getCapturedElements( ElementCapture.Primary );
    054
    055    if( remove.isEmpty() )
    056      return false;
    057
    058    for( FlowElement flowElement : remove )
    059      ElementGraphs.removeAndContract( graph, flowElement );
    060
    061    return true;
    062    }
    063  }