// @(#)$Id: Dictionary.refines-spec,v 1.6 2006/11/28 03:51:11 chalin Exp $

// Copyright (C) 2005 Iowa State University
//
// This file is part of the runtime library of the Java Modeling Language.
//
// 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 JML; see the file LesserGPL.txt.  If not, write to the Free
// Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
// 02110-1301  USA.

package java.util;

public abstract class Dictionary {
    //@ public ghost \TYPE keyType = \type(Object);
    //@ public ghost \TYPE elementType = \type(Object);

    //@ pure
    public Dictionary();

    //@ modifies \nothing;
    public abstract int size();

    //@ modifies \nothing;
    public abstract boolean isEmpty();

    //@ modifies \nothing;
    public abstract /*@non_null*/ Enumeration keys();

    //@ modifies \nothing;
    public abstract /*@non_null*/ Enumeration elements();

    // NOTE:
    // While the spec of Dictionary states that key and value cannot be null,
    // due to behavioral subtyping and the fact that subclasses of Dictionary allow
    // key and value to be null, we must declare these formal parameters as nullable.

    //@ requires key != null;
    //@ modifies \nothing;
    public abstract /*@ nullable @*/ Object get(/*@ nullable @*/ Object key);

    //@ requires key != null;
    //@ requires value != null;
    public abstract /*@ nullable @*/ Object put(/*@ nullable @*/ Object key, /*@ nullable @*/ Object value);

    //@ requires key != null;
    public abstract /*@ nullable @*/ Object remove(/*@ nullable @*/ Object key);
}