001/*
002 * Copyright (c) 2016 Chris K Wensel <chris@wensel.net>. 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.expression;
022
023import java.util.Set;
024
025import cascading.flow.FlowElement;
026import cascading.flow.planner.PlannerContext;
027import cascading.flow.planner.Scope;
028import cascading.flow.planner.graph.ElementGraph;
029
030/**
031 *
032 */
033public class JoinEdgesSameSourceScopeExpression extends ScopeExpression
034  {
035  public static final JoinEdgesSameSourceScopeExpression ALL_SAME_SOURCE = new JoinEdgesSameSourceScopeExpression();
036
037  public JoinEdgesSameSourceScopeExpression()
038    {
039    }
040
041  @Override
042  public boolean applies( PlannerContext plannerContext, ElementGraph elementGraph, Scope scope )
043    {
044    FlowElement edgeSource = elementGraph.getEdgeSource( scope );
045    FlowElement edgeTarget = elementGraph.getEdgeTarget( scope );
046    Set<Scope> allEdgesBetween = elementGraph.getAllEdges( edgeSource, edgeTarget );
047
048    if( allEdgesBetween.size() == 1 )
049      return false;
050
051    return allEdgesBetween.equals( elementGraph.incomingEdgesOf( edgeTarget ) );
052    }
053  }