/*
* JBoss, Home of Professional Open Source.
* 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.List;
import org.teiid.client.plan.PlanNode;
import org.teiid.common.buffer.BlockedException;
import org.teiid.core.TeiidComponentException;
import org.teiid.core.TeiidProcessingException;
import org.teiid.logging.LogManager;
import org.teiid.query.processor.ProcessorPlan;
import org.teiid.query.sql.lang.Criteria;
/**
* <p>This instruction an holds an if block and an else block and a criteria that determines
* which block will be executed. These blocks are {@link Program} objects that could contain
* nested if-else block. Therefore, this <code>ProgramInstruction</code>
* implements an arbitrarily deep if-else if-....else block.</p>
*
* <p>During processing, the Criteria is evaluated and if it evaluates to true,
* the "if" block is executed else the "else" block if there is one is executed. These
* programs are placed on the {@link ProgramEnvironment#getProgramStack stack}.</p>
*/
public class IfInstruction extends ProgramInstruction {
// the "if" block
private Program ifProgram;
// optional "else" block
private Program elseProgram;
// criteria on the "if" block
private Criteria condition;
/**
* Constructor for IfInstruction.
* @param condition The <code>Criteria</code> used to determine which block to execute
* @param ifProgram The <code>Program</code> representing the "if" block
* @param elseProgram The <code>Program</code> representing the "else" block
*/
public IfInstruction(Criteria condition, Program ifProgram, Program elseProgram) {
this.condition = condition;
this.ifProgram = ifProgram;
this.elseProgram = elseProgram;
}
/**
* Constructor for IfInstruction.
* @param condition The <code>Criteria</code> used to determine which block to execute
* @param ifProgram The <code>Program</code> representing the "if" block
*/
public IfInstruction(Criteria condition, Program ifProgram) {
this(condition, ifProgram, null);
}
/**
* This instruction will evaluate it's criteria, if it evaluates
* to true, it will push the corresponding sub Program on to the top of the
* program stack, and break from the loop. Regardless if whether any criteria
* evaluate to true, this instruction will increment the program counter of the
* current program.
* @throws TeiidProcessingException
* @see ProgramInstruction#process(ProcedurePlan)
*/
public void process(ProcedurePlan procEnv)
throws BlockedException, TeiidComponentException, TeiidProcessingException {
boolean evalValue = procEnv.evaluateCriteria(condition);
if(evalValue) {
LogManager.logTrace(org.teiid.logging.LogConstants.CTX_DQP, new Object[]{"IFInstruction: "+ //$NON-NLS-1$
" The criteria on the if block evaluated to true, processing the if block"}); //$NON-NLS-1$
//push the "if" Program onto the stack
procEnv.push(ifProgram);
} else if(elseProgram != null) {
LogManager.logTrace(org.teiid.logging.LogConstants.CTX_DQP, new Object[]{"IFInstruction: "+ //$NON-NLS-1$
" The criteria on the if block evaluated to false, processing the else block"}); //$NON-NLS-1$
//push the "else" Program onto the stack
procEnv.push(elseProgram);
}
}
public Program getIfProgram(){ //Defect 13291 - made public to support changes to ProcedurePlan
return this.ifProgram;
}
public Program getElseProgram(){ //Defect 13291 - made public to support changes to ProcedurePlan
return this.elseProgram;
}
/**
* Returns a deep clone
*/
public IfInstruction clone(){
Program cloneIf = (Program) this.ifProgram.clone();
Program cloneElse = null;
if(elseProgram != null) {
cloneElse = (Program) this.elseProgram.clone();
}
IfInstruction clone = new IfInstruction(this.condition, cloneIf, cloneElse);
return clone;
}
public String toString() {
return "IF INSTRUCTION:"; //$NON-NLS-1$
}
public PlanNode getDescriptionProperties() {
PlanNode props = new PlanNode("IF"); //$NON-NLS-1$
props.addProperty(PROP_CRITERIA, this.condition.toString());
props.addProperty(PROP_THEN, this.ifProgram.getDescriptionProperties());
if(elseProgram != null) {
props.addProperty(PROP_ELSE, this.elseProgram.getDescriptionProperties());
}
return props;
}
@Override
public void getChildPlans(List<ProcessorPlan> plans) {
ifProgram.getChildPlans(plans);
if (elseProgram != null) {
elseProgram.getChildPlans(plans);
}
}
}