Package org.teiid.query.processor.proc

Source Code of org.teiid.query.processor.proc.LoopInstruction

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* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.  Some portions may be licensed
* to Red Hat, Inc. under one or more contributor license agreements.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA.
*/

/*
*/
package org.teiid.query.processor.proc;

import static org.teiid.query.analysis.AnalysisRecord.*;

import java.util.ArrayList;
import java.util.List;

import org.teiid.client.plan.PlanNode;
import org.teiid.core.TeiidComponentException;
import org.teiid.core.TeiidProcessingException;
import org.teiid.query.processor.ProcessorPlan;
import org.teiid.query.sql.symbol.ElementSymbol;
import org.teiid.query.sql.symbol.SingleElementSymbol;
import org.teiid.query.sql.util.VariableContext;


/**
*/
public class LoopInstruction extends CreateCursorResultSetInstruction implements RepeatedInstruction {
    // the loop block
    private Program loopProgram;
   
    private List elements;
   
    public LoopInstruction(Program loopProgram, String rsName, ProcessorPlan plan) {
        super(rsName, plan, false);
        this.loopProgram = loopProgram;
    }

    public void process(ProcedurePlan procEnv) throws TeiidComponentException {
        List currentRow = procEnv.getCurrentRow(rsName);
        VariableContext varContext = procEnv.getCurrentVariableContext();
        //set results to the variable context(the cursor.element is treated as variable)
        if(this.elements == null){
            List schema = procEnv.getSchema(rsName);
            elements = new ArrayList(schema.size());
            for(int i=0; i< schema.size(); i++){
                // defect 13432 - schema may contain AliasSymbols. Cast to SingleElementSymbol instead of ElementSymbol
                SingleElementSymbol element = (SingleElementSymbol)schema.get(i);
                elements.add(new ElementSymbol(rsName + "." + element.getShortName()));              //$NON-NLS-1$
            }
        }
        for(int i=0; i< elements.size(); i++){
            varContext.setValue((ElementSymbol)elements.get(i), currentRow.get(i));              
        }
    }
   
    /**
     * Returns a deep clone
     */
    public LoopInstruction clone(){
        ProcessorPlan clonedPlan = this.plan.clone();
        return new LoopInstruction((Program)this.loopProgram.clone(), this.rsName, clonedPlan);
    }
   
    public String toString() {
        return "LOOP INSTRUCTION: " + this.rsName; //$NON-NLS-1$
    }
   
    public PlanNode getDescriptionProperties() {
        PlanNode props = new PlanNode("LOOP"); //$NON-NLS-1$
        props.addProperty(PROP_SQL, this.plan.getDescriptionProperties());
        props.addProperty(PROP_RESULT_SET, this.rsName);
        props.addProperty(PROP_PROGRAM, this.loopProgram.getDescriptionProperties());
        return props;
    }

    public boolean testCondition(ProcedurePlan procEnv) throws TeiidComponentException, TeiidProcessingException {
        if(!procEnv.resultSetExists(rsName)) {
            procEnv.executePlan(plan, rsName, null, false);           
        }
       
        return procEnv.iterateCursor(rsName);
    }

    /**
     * @see org.teiid.query.processor.proc.RepeatedInstruction#getNestedProgram()
     */
    public Program getNestedProgram() {
        return loopProgram;
    }

    public void postInstruction(ProcedurePlan procEnv) throws TeiidComponentException {
        procEnv.removeResults(rsName);
    }
   
    @Override
    public void getChildPlans(List<ProcessorPlan> plans) {
      super.getChildPlans(plans);
      this.loopProgram.getChildPlans(plans);
    }

}
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