/*
* Copyright (C) 2010 Brockmann Consult GmbH (info@brockmann-consult.de)
*
* 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 3 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, see http://www.gnu.org/licenses/
*/
package com.bc.ceres.binio.expr;
import com.bc.ceres.binio.CompoundData;
import java.io.IOException;
public class ConstantExpr extends AbstractExpression {
private final Expression expression;
private volatile Object value;
public ConstantExpr(Object value) {
this.expression = null;
this.value = value;
}
public ConstantExpr(Expression expression) {
this.expression = expression;
this.expression.setParent(this);
}
public boolean isConstant() {
return true;
}
public Object evaluate(CompoundData context) throws IOException {
if (value == null && expression != null) {
synchronized (this) {
if (value == null) {
value = expression.evaluate(context);
}
}
}
return value;
}
}