content: /*
   * 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.asterix.optimizer.rules;
  
  import java.util.ArrayList;
  
  import org.apache.asterix.lang.common.util.FunctionUtil;
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.commons.lang3.mutable.Mutable;
  import org.apache.commons.lang3.mutable.MutableObject;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
  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.LogicalOperatorTag;
  import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
  import org.apache.hyracks.algebricks.core.algebra.expressions.StatefulFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
  import org.apache.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
  import org.apache.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
  import org.apache.hyracks.algebricks.core.algebra.operators.physical.RunningAggregatePOperator;
  import org.apache.hyracks.algebricks.core.algebra.properties.UnpartitionedPropertyComputer;
  import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
  
  public class PullPositionalVariableFromUnnestRule implements IAlgebraicRewriteRule {
  
      @Override
      public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
              throws AlgebricksException {
          return false;
      }
  
      @Override
      public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
              throws AlgebricksException {
          AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
          if (op.getOperatorTag() != LogicalOperatorTag.UNNEST) {
              return false;
          }
          UnnestOperator unnest = (UnnestOperator) op;
          LogicalVariable p = unnest.getPositionalVariable();
          if (p == null) {
              return false;
          }
          ArrayList<LogicalVariable> rOpVars = new ArrayList<LogicalVariable>();
          rOpVars.add(p);
          ArrayList<Mutable<ILogicalExpression>> rOpExprList = new ArrayList<Mutable<ILogicalExpression>>();
          StatefulFunctionCallExpression fce = new StatefulFunctionCallExpression(
                  FunctionUtil.getFunctionInfo(BuiltinFunctions.TID), UnpartitionedPropertyComputer.INSTANCE);
          fce.setSourceLocation(op.getSourceLocation());
          rOpExprList.add(new MutableObject<ILogicalExpression>(fce));
          RunningAggregateOperator rOp = new RunningAggregateOperator(rOpVars, rOpExprList);
          rOp.setSourceLocation(unnest.getSourceLocation());
          rOp.setExecutionMode(unnest.getExecutionMode());
          RunningAggregatePOperator rPop = new RunningAggregatePOperator();
          rOp.setPhysicalOperator(rPop);
          rOp.getInputs().add(new MutableObject<ILogicalOperator>(unnest));
          opRef.setValue(rOp);
          unnest.setPositionalVariable(null);
          context.computeAndSetTypeEnvironmentForOperator(rOp);
          context.computeAndSetTypeEnvironmentForOperator(unnest);
          return true;
      }
  }
  