    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.hadoop.planner.rule.expression;
    022
    023import cascading.flow.planner.iso.expression.ElementCapture;
    024import cascading.flow.planner.iso.expression.ElementExpression;
    025import cascading.flow.planner.iso.expression.ExpressionGraph;
    026import cascading.flow.planner.iso.expression.FlowElementExpression;
    027import cascading.flow.planner.iso.expression.ScopeExpression;
    028import cascading.flow.planner.iso.expression.TypeExpression.Topo;
    029import cascading.flow.planner.rule.RuleExpression;
    030import cascading.flow.planner.rule.expressiongraph.SyncPipeExpressionGraph;
    031import cascading.pipe.Checkpoint;
    032import cascading.pipe.Group;
    033import cascading.pipe.HashJoin;
    034import cascading.pipe.Pipe;
    035import cascading.tap.Tap;
    036
    037import static cascading.flow.planner.iso.expression.OrElementExpression.or;
    038
    039/**
    040 *
    041 */
    042public class BalanceGroupSplitTriangleExpression extends RuleExpression
    043  {
    044  public static final FlowElementExpression SHARED_GROUP = new FlowElementExpression( Group.class, Topo.Split );
    045  public static final ElementExpression SHARED_LHS = or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ), new FlowElementExpression( Checkpoint.class ) );
    046  public static final ElementExpression SHARED_RHS = or( new FlowElementExpression( HashJoin.class ), new FlowElementExpression( Group.class ), new FlowElementExpression( Tap.class ), new FlowElementExpression( Checkpoint.class ) );
    047
    048  public BalanceGroupSplitTriangleExpression()
    049    {
    050    super(
    051      new SyncPipeExpressionGraph(),
    052
    053      new ExpressionGraph()
    054        .arc(
    055          SHARED_GROUP,
    056          ScopeExpression.ANY,
    057          SHARED_LHS
    058        )
    059
    060        .arc(
    061          SHARED_GROUP,
    062          ScopeExpression.ANY,
    063          SHARED_RHS
    064        )
    065
    066        .arc(
    067          SHARED_LHS,
    068          ScopeExpression.ANY,
    069          SHARED_RHS
    070        ),
    071
    072      // sub-graph to match has out degree captured above
    073      new ExpressionGraph()
    074        .arcs(
    075          new FlowElementExpression( ElementCapture.Primary, Pipe.class, Topo.SplitOnly )
    076        )
    077    );
    078    }
    079  }