001/*
002 * Copyright (c) 2007-2015 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.graph.ElementGraph;
027import cascading.flow.planner.graph.ElementGraphs;
028import cascading.flow.planner.iso.expression.ElementCapture;
029import cascading.flow.planner.iso.expression.ExpressionGraph;
030import cascading.flow.planner.iso.finder.Match;
031import cascading.util.Util;
032
033/**
034 *
035 */
036public class ReplaceGraphTransformer extends MutateGraphTransformer
037  {
038  public ReplaceGraphTransformer( ExpressionGraph filter )
039    {
040    super( filter );
041    }
042
043  public ReplaceGraphTransformer( GraphTransformer graphTransformer, ExpressionGraph filter )
044    {
045    super( graphTransformer, filter );
046    }
047
048  @Override
049  protected boolean transformGraphInPlaceUsing( Transformed<ElementGraph> transformed, ElementGraph graph, Match match )
050    {
051    Set<FlowElement> replace = match.getCapturedElements( ElementCapture.Primary );
052    Set<FlowElement> replaceWith = match.getCapturedElements( ElementCapture.Secondary );
053
054    if( replace.isEmpty() || replaceWith.isEmpty() )
055      return false;
056
057    if( replace.size() != 1 )
058      throw new IllegalStateException( "too many captured elements" );
059
060    if( replaceWith.size() != 1 )
061      throw new IllegalStateException( "too many target elements" );
062
063    ElementGraphs.replaceElementWith( graph, Util.getFirst( replace ), Util.getFirst( replaceWith ) );
064
065    return true;
066    }
067  }