/* * 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.type.Type;import org.tzi.use.uml.ocl.value.Value;/** * OCL Let-expression. * * @version     $ProjectVersion: 2-3-0-release.1 $ * @author  Mark Richters */public final class ExpLet extends Expression {    private String fVarname;    private Type fVarType;    private Expression fVarExpr;    private Expression fInExpr;        public ExpLet(String varname,                   Type varType,                  Expression varExpr,                  Expression inExpr)        throws ExpInvalidException    {        super(inExpr.type());        fVarname = varname;        fVarType = varType;        fVarExpr = varExpr;        fInExpr = inExpr;        if (! fVarExpr.type().isSubtypeOf(fVarType) )            throw new ExpInvalidException(                                          "Type of variable expression `" + fVarExpr.type() +                                          "' does not match declared type `" + fVarType + "'.");    }    /**     * Evaluates expression and returns result value.     */    public Value eval(EvalContext ctx) {        ctx.enter(this);        Value res = null;        Value varValue = fVarExpr.eval(ctx);        ctx.pushVarBinding(fVarname, varValue);        res = fInExpr.eval(ctx);        ctx.popVarBinding();        ctx.exit(this, res);        return res;    }    public String toString() {        return "let " + fVarname + " : " + fVarType + " = " +             fVarExpr + " in " + fInExpr;    }}