001/*
002 * Copyright (c) 2007-2016 Concurrent, 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  }