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/* ExpressionLoader.java
* =========================================================================
* This file is part of the GrInvIn project - http://www.grinvin.org
*
* Copyright (C) 2005-2008 Universiteit Gent
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program 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
* General Public License for more details.
*
* A copy of the GNU General Public License can be found in the file
* LICENSE.txt provided with the source distribution of this program (see
* the META-INF directory in the source jar). This license can also be
* found on the GNU website at http://www.gnu.org/licenses/gpl.html.
*
* If you did not receive a copy of the GNU General Public License along
* with this program, contact the lead developer, or write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
package org.grinvin.expr;
import org.grinvin.invariants.InvariantManager;
import org.grinvin.invariants.UnknownInvariantException;
import org.grinvin.io.IOFormatException;
import org.jdom.DataConversionException;
import org.jdom.Element;
/**
* Helper methods for loading expressions from disk.
*/
public final class ExpressionLoader {
private ExpressionLoader() {
// not to be instantiated
}
public static Expression loadExpression(Element element) throws IOFormatException {
String name = element.getName();
if ("integer".equals(name)) {
return loadIntegerLiteral(element);
} else if ("invariant".equals(name)) {
return loadInvariant(element);
} else if ("compound".equals(name)) {
return loadCompound(element);
} else
throw new IOFormatException("Invalid name of expression element");
}
private static Expression loadIntegerLiteral(Element element) throws IOFormatException {
try {
return new IntegerLiteral(
element.getAttribute("value").getIntValue()
);
} catch (DataConversionException ex) {
throw new IOFormatException("No valid value for integer literal", ex);
}
}
private static Expression loadInvariant(Element element) throws IOFormatException {
try {
String id = element.getAttributeValue("id");
if (id == null)
id = element.getAttributeValue("invariantId");
return InvariantManager.getInstance().getInvariantExpressionNode(id);
} catch (UnknownInvariantException ex) {
throw new IOFormatException("Unknown invariant in expression", ex);
}
}
private static Expression loadCompound(Element element) throws IOFormatException {
Operator operator = StandardOperator.valueOf(StandardOperator.class, element.getAttributeValue("operator"));
if (operator == null)
throw new IOFormatException ("Unkown operator");
int nr = operator.getNumberOfArguments();
Expression[] children = new Expression[nr];
int i = 0;
for (Object obj : element.getChildren()) {
Element child = (Element)obj;
if (i >= nr)
throw new IOFormatException ("Too many arguments in compound expression");
children[i] =loadExpression (child);
i++;
}
if (i < nr)
throw new IOFormatException ("Not enough arguments in compound expression");
return new Compound (operator, children);
}
}
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