org.apache.asterix.optimizer.rules.IfElseToSwitchCaseFunctionRule Maven / Gradle / Ivy

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/*
 * 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 java.util.List;

import org.apache.commons.lang3.mutable.Mutable;
import org.apache.commons.lang3.mutable.MutableObject;

import org.apache.asterix.aql.util.FunctionUtils;
import org.apache.asterix.om.functions.AsterixBuiltinFunctions;
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.ILogicalPlan;
import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext;
import org.apache.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
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.AbstractFunctionCallExpression;
import org.apache.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
import org.apache.hyracks.algebricks.core.algebra.expressions.ScalarFunctionCallExpression;
import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
import org.apache.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
import org.apache.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
import org.apache.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;

public class IfElseToSwitchCaseFunctionRule implements IAlgebraicRewriteRule {

    @Override
    public boolean rewritePre(Mutable opRef, IOptimizationContext context) throws AlgebricksException {
        return false;
    }

    @Override
    public boolean rewritePost(Mutable opRef, IOptimizationContext context)
            throws AlgebricksException {
        AbstractLogicalOperator op1 = (AbstractLogicalOperator) opRef.getValue();
        if (op1.getOperatorTag() != LogicalOperatorTag.ASSIGN)
            return false;

        AssignOperator assignOp = (AssignOperator) op1;
        List> assignExprs = assignOp.getExpressions();
        if (assignExprs.size() > 1)
            return false;
        ILogicalExpression expr = assignExprs.get(0).getValue();
        if (expr.getExpressionTag() == LogicalExpressionTag.FUNCTION_CALL) {
            AbstractFunctionCallExpression funcExpr = (AbstractFunctionCallExpression) expr;
            if (!funcExpr.getFunctionIdentifier().equals(AsterixBuiltinFunctions.CONCAT_NON_NULL))
                return false;
        }

        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op1.getInputs().get(0).getValue();
        if (op2.getOperatorTag() != LogicalOperatorTag.SUBPLAN)
            return false;

        SubplanOperator subplan = (SubplanOperator) op2;
        List subPlans = subplan.getNestedPlans();
        List> arguments = new ArrayList>();
        for (ILogicalPlan plan : subPlans) {
            List> roots = plan.getRoots();

            AbstractLogicalOperator nestedRoot = (AbstractLogicalOperator) roots.get(0).getValue();
            if (nestedRoot.getOperatorTag() != LogicalOperatorTag.SELECT)
                return false;
            SelectOperator selectOp = (SelectOperator) nestedRoot;

            AbstractLogicalOperator nestedNextOp = (AbstractLogicalOperator) nestedRoot.getInputs().get(0).getValue();
            if (nestedNextOp.getOperatorTag() != LogicalOperatorTag.ASSIGN)
                return false;
            AssignOperator assignRoot = (AssignOperator) nestedNextOp;
            Mutable actionExprRef = assignRoot.getExpressions().get(0);

            arguments.add(selectOp.getCondition());
            arguments.add(actionExprRef);
            AbstractLogicalOperator nestedBottomOp = (AbstractLogicalOperator) assignRoot.getInputs().get(0).getValue();

            if (nestedBottomOp.getOperatorTag() != LogicalOperatorTag.NESTEDTUPLESOURCE)
                return false;
        }

        AbstractLogicalOperator op3 = (AbstractLogicalOperator) op2.getInputs().get(0).getValue();
        if (op3.getOperatorTag() != LogicalOperatorTag.ASSIGN)
            return false;

        AssignOperator bottomAssign = (AssignOperator) op3;
        LogicalVariable conditionVar = bottomAssign.getVariables().get(0);
        Mutable switchCondition = new MutableObject(
                new VariableReferenceExpression(conditionVar));
        List> argumentRefs = new ArrayList>();
        argumentRefs.add(switchCondition);
        argumentRefs.addAll(arguments);

        /** replace the branch conditions */
        for (int i = 0; i < arguments.size(); i += 2) {
            if (arguments.get(i).getValue().equals(switchCondition.getValue())) {
                arguments.get(i).setValue(ConstantExpression.TRUE);
            } else {
                arguments.get(i).setValue(ConstantExpression.FALSE);
            }
        }

        ILogicalExpression callExpr = new ScalarFunctionCallExpression(
                FunctionUtils.getFunctionInfo(AsterixBuiltinFunctions.SWITCH_CASE), argumentRefs);

        assignOp.getInputs().get(0).setValue(op3);
        assignOp.getExpressions().get(0).setValue(callExpr);
        context.computeAndSetTypeEnvironmentForOperator(assignOp);
        return true;
    }
}