001/* 002 * Copyright (c) 2016 Chris K Wensel <chris@wensel.net>. All Rights Reserved. 003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved. 004 * 005 * Project and contact information: http://www.cascading.org/ 006 * 007 * This file is part of the Cascading project. 008 * 009 * Licensed under the Apache License, Version 2.0 (the "License"); 010 * you may not use this file except in compliance with the License. 011 * You may obtain a copy of the License at 012 * 013 * http://www.apache.org/licenses/LICENSE-2.0 014 * 015 * Unless required by applicable law or agreed to in writing, software 016 * distributed under the License is distributed on an "AS IS" BASIS, 017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 018 * See the License for the specific language governing permissions and 019 * limitations under the License. 020 */ 021 022package cascading.flow.planner.iso.transformer; 023 024import cascading.flow.planner.PlannerContext; 025import cascading.flow.planner.graph.ElementGraph; 026import cascading.flow.planner.graph.ElementGraphs; 027import cascading.flow.planner.graph.ElementSubGraph; 028import cascading.flow.planner.iso.expression.ExpressionGraph; 029import cascading.flow.planner.iso.finder.GraphFinder; 030import cascading.flow.planner.iso.finder.Match; 031import cascading.flow.planner.rule.TransformException; 032 033/** 034 * Class SubGraphTransformer will return a bounded sub-graph after matching a sub-graph within a contracted graph. 035 */ 036public class SubGraphTransformer extends GraphTransformer<ElementGraph, ElementSubGraph> 037 { 038 private GraphTransformer graphTransformer; 039 private ExpressionGraph subGraphMatcher; 040 private GraphFinder subGraphFinder; 041 private boolean findAllPrimaries = false; 042 043 public SubGraphTransformer( GraphTransformer graphTransformer, ExpressionGraph subGraphMatcher ) 044 { 045 this.graphTransformer = graphTransformer; 046 this.subGraphMatcher = subGraphMatcher; 047 this.subGraphFinder = new GraphFinder( subGraphMatcher ); 048 this.findAllPrimaries = subGraphMatcher.supportsNonRecursiveMatch(); 049 } 050 051 public Transformed<ElementSubGraph> transform( PlannerContext plannerContext, ElementGraph rootGraph ) 052 { 053 Transformed<ElementSubGraph> transformed = new Transformed<>( plannerContext, this, subGraphMatcher, rootGraph ); 054 055 try 056 { 057 Transformed contractedTransformed = graphTransformer.transform( plannerContext, rootGraph ); // contracted graph transform 058 059 transformed.addChildTransform( contractedTransformed ); 060 061 // apply contracted sub-graph matcher to get the bounded sub-graph of the original graph 062 ElementGraph contractedGraph = contractedTransformed.getEndGraph(); 063 064 Match match = findAllPrimaries ? subGraphFinder.findAllMatches( plannerContext, contractedGraph ) : subGraphFinder.findFirstMatch( plannerContext, contractedGraph ); 065 066 if( !match.foundMatch() ) 067 return transformed; 068 069 ElementGraph contractedSubGraph = match.getMatchedGraph(); 070 071 ElementSubGraph resultSubGraph = asSubGraphOf( rootGraph, contractedSubGraph ); // the bounded sub-graph of the rootGraph 072 073 transformed.setEndGraph( resultSubGraph ); 074 075 return transformed; 076 } 077 catch( Throwable throwable ) 078 { 079 throw new TransformException( throwable, transformed ); 080 } 081 } 082 083 protected ElementSubGraph asSubGraphOf( ElementGraph rootGraph, ElementGraph contractedSubGraph ) 084 { 085 return ElementGraphs.asSubGraph( rootGraph, contractedSubGraph, null ); 086 } 087 }