    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.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  }