/*
* 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.translator.jdbc.oracle;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.teiid.language.Condition;
import org.teiid.language.Expression;
import org.teiid.language.Function;
import org.teiid.language.LanguageFactory;
import org.teiid.language.Literal;
import org.teiid.language.SearchedWhenClause;
import org.teiid.language.AndOr.Operator;
import org.teiid.translator.SourceSystemFunctions;
import org.teiid.translator.TypeFacility;
import org.teiid.translator.jdbc.FunctionModifier;
/**
* This Function modifier used to support ANSI concat on Oracle 9i.
* <code>
* CONCAT(a, b) ==> CASE WHEN (a is NULL OR b is NULL) THEN NULL ELSE CONCAT(a, b)
* </code>
*/
public class ConcatFunctionModifier extends FunctionModifier {
private LanguageFactory langFactory;
/**
* @param langFactory
*/
public ConcatFunctionModifier(LanguageFactory langFactory) {
this.langFactory = langFactory;
}
@Override
public List<?> translate(Function function) {
Expression a = function.getParameters().get(0);
Expression b = function.getParameters().get(1);
List<Condition> crits = new ArrayList<Condition>();
Literal nullValue = langFactory.createLiteral(null, TypeFacility.RUNTIME_TYPES.STRING);
if (isNull(a)) {
return Arrays.asList(nullValue);
} else if (!isNotNull(a)) {
crits.add(langFactory.createIsNullCriteria(a, false));
}
if (isNull(b)) {
return Arrays.asList(nullValue);
} else if (!isNotNull(b)) {
crits.add(langFactory.createIsNullCriteria(b, false));
}
Condition crit = null;
if (crits.isEmpty()) {
return null;
} else if (crits.size() == 1) {
crit = crits.get(0);
} else {
crit = langFactory.createAndOr(Operator.OR, crits.get(0), crits.get(1));
}
List<SearchedWhenClause> cases = Arrays.asList(langFactory.createSearchedWhenCondition(crit, nullValue));
return Arrays.asList(langFactory.createSearchedCaseExpression(cases, function, TypeFacility.RUNTIME_TYPES.STRING));
}
public static boolean isNotNull(Expression expr) {
if (expr instanceof Literal) {
Literal literal = (Literal)expr;
return literal.getValue() != null;
}
if (expr instanceof Function) {
Function function = (Function)expr;
if (function.getName().equalsIgnoreCase("NVL") || function.getName().equalsIgnoreCase(SourceSystemFunctions.IFNULL)) { //$NON-NLS-1$
return isNotNull(function.getParameters().get(1));
}
}
return false;
}
private boolean isNull(Expression expr) {
if (expr instanceof Literal) {
Literal literal = (Literal)expr;
return literal.getValue() == null;
}
return false;
}
}