/*
* 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.db2;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.teiid.language.Comparison;
import org.teiid.language.Expression;
import org.teiid.language.Function;
import org.teiid.language.Literal;
import org.teiid.language.SearchedCase;
import org.teiid.language.SearchedWhenClause;
import org.teiid.language.Comparison.Operator;
import org.teiid.translator.SourceSystemFunctions;
import org.teiid.translator.TypeFacility;
import org.teiid.translator.jdbc.AliasModifier;
public class SubstringFunctionModifier extends AliasModifier {
public SubstringFunctionModifier() {
super("substr"); //$NON-NLS-1$
}
@Override
public List<?> translate(Function function) {
this.modify(function);
if (function.getParameters().size() != 3) {
return null;
}
//case when length > LENGTH(string) - start + 1 then LENGTH(string) - start + 1 case when length > 0 then length end
Expression length = function.getParameters().get(2);
List<SearchedWhenClause> clauses = new ArrayList<SearchedWhenClause>(2);
Boolean isNegative = null;
if (length instanceof Literal) {
Literal l = (Literal)length;
if (!l.isMultiValued()) {
int value = (Integer)l.getValue();
isNegative = value < 0;
}
}
Expression maxLength = new Function(
SourceSystemFunctions.SUBTRACT_OP,
Arrays.asList(new Function(
SourceSystemFunctions.LENGTH,
Arrays.asList(function.getParameters().get(0)),
TypeFacility.RUNTIME_TYPES.INTEGER),
new Function(
SourceSystemFunctions.SUBTRACT_OP,
Arrays.asList(
function.getParameters().get(1),
new Literal(1, TypeFacility.RUNTIME_TYPES.INTEGER)),
TypeFacility.RUNTIME_TYPES.INTEGER)),
TypeFacility.RUNTIME_TYPES.INTEGER);
clauses.add(new SearchedWhenClause(new Comparison(length, maxLength, Operator.GT), maxLength));
Expression defaultExpr = null;
if (isNegative == null) {
clauses.add(new SearchedWhenClause(new Comparison(length, new Literal(0, TypeFacility.RUNTIME_TYPES.INTEGER), Operator.GT), length));
} else if (isNegative) {
//TODO: could be done in the rewriter
function.getParameters().set(2, null);
return null;
} else {
defaultExpr = length;
}
SearchedCase sc = new SearchedCase(clauses,
defaultExpr, TypeFacility.RUNTIME_TYPES.INTEGER);
function.getParameters().set(2, sc);
return null;
}
}