| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.hyracks.algebricks.rewriter.rules; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| |
| import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException; |
| import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator; |
| import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext; |
| import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities; |
| |
| /** |
| * Inlines variables that are referenced exactly once. |
| * |
| * Preconditions/Assumptions: |
| * Assumes no projects are in the plan. |
| * |
| * Example assuming variable $$3 is referenced exactly once. |
| * |
| * Before plan: |
| * select (funcA($$3)) |
| * ... |
| * assign [$$3] <- [field-access($$0, 1)] |
| * |
| * After plan: |
| * select (funcA(field-access($$0, 1)) |
| * ... |
| * assign [] <- [] |
| */ |
| public class InlineSingleReferenceVariablesRule extends InlineVariablesRule { |
| |
| // Maps from variable to a list of operators using that variable. |
| protected Map<LogicalVariable, List<ILogicalOperator>> usedVarsMap = new HashMap<LogicalVariable, List<ILogicalOperator>>(); |
| protected List<LogicalVariable> usedVars = new ArrayList<LogicalVariable>(); |
| |
| @Override |
| protected void prepare(IOptimizationContext context) { |
| super.prepare(context); |
| usedVarsMap.clear(); |
| usedVars.clear(); |
| } |
| |
| @Override |
| protected boolean performFinalAction() throws AlgebricksException { |
| boolean modified = false; |
| for (Map.Entry<LogicalVariable, List<ILogicalOperator>> entry : usedVarsMap.entrySet()) { |
| // Perform replacement only if variable is referenced a single time. |
| if (entry.getValue().size() == 1) { |
| ILogicalOperator op = entry.getValue().get(0); |
| if (!op.requiresVariableReferenceExpressions()) { |
| inlineVisitor.setOperator(op); |
| inlineVisitor.setTargetVariable(entry.getKey()); |
| if (op.acceptExpressionTransform(inlineVisitor)) { |
| modified = true; |
| } |
| inlineVisitor.setTargetVariable(null); |
| } |
| } |
| } |
| return modified; |
| } |
| |
| @Override |
| protected boolean performBottomUpAction(AbstractLogicalOperator op) throws AlgebricksException { |
| usedVars.clear(); |
| VariableUtilities.getUsedVariables(op, usedVars); |
| for (LogicalVariable var : usedVars) { |
| List<ILogicalOperator> opsUsingVar = usedVarsMap.get(var); |
| if (opsUsingVar == null) { |
| opsUsingVar = new ArrayList<ILogicalOperator>(); |
| usedVarsMap.put(var, opsUsingVar); |
| } |
| opsUsingVar.add(op); |
| } |
| return false; |
| } |
| } |