/* * USE - UML based specification environment * Copyright (C) 1999-2004 Mark Richters, University of Bremen * * 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. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. *//* $ProjectHeader: use 2-3-0-release.1 Mon, 12 Sep 2005 20:18:33 +0200 green $ */package org.tzi.use.uml.ocl.expr;import org.tzi.use.uml.ocl.value.BooleanValue;import org.tzi.use.uml.ocl.value.UndefinedValue;import org.tzi.use.uml.ocl.value.Value;/** * If-then-else-endif. * * @version     $ProjectVersion: 2-3-0-release.1 $ * @author  Mark Richters */public final class ExpIf extends Expression {    private Expression fCondition;    private Expression fThenExp;    private Expression fElseExp;        public ExpIf(Expression condition,                 Expression thenExp,                 Expression elseExp)        throws ExpInvalidException    {        // result type is type of then/else branch (must be identical)        super(thenExp.type());        fCondition = condition;        fCondition.assertBoolean();        fThenExp = thenExp;        fElseExp = elseExp;        if (! fThenExp.type().equals(fElseExp.type()) )            throw new ExpInvalidException(                                          "Branches of if expression have different type, " +                                          "found `" + fThenExp.type() +                                           "' and `" + fElseExp.type() + "'.");    }    /**     * Evaluates expression and returns result value. If the condition     * evaluates to true return the value of the "then"     * expression. Otherwise, if the condition evaluates to undefined     * or false, the result is given by the "else" expression.     *       */    public Value eval(EvalContext ctx) {        ctx.enter(this);        Value res = new UndefinedValue(type());        Value condValue = fCondition.eval(ctx);        // condition may be undefined        if (condValue.isDefined() ) {            boolean cond = ((BooleanValue) condValue).value();            if (cond )                res = fThenExp.eval(ctx);            else                res = fElseExp.eval(ctx);        }        ctx.exit(this, res);        return res;    }    public String toString() {        return "if " + fCondition +             " then " + fThenExp +             " else " + fElseExp +            " endif";    }}