// @(#)$Id: ArcType.jml,v 1.7 2005/12/23 17:02:06 chalin Exp $

// Copyright (C) 1998, 1999 Iowa State University

// This file is part of JML

// JML 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, or (at your option)
// any later version.

// JML 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 JML; see the file COPYING.  If not, write to
// the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.


package org.jmlspecs.samples.digraph;

import org.jmlspecs.models.JMLType;

/*@ pure @*/ public class ArcType implements JMLType {

    //@ public model NodeType from;
    //@ public model NodeType to;
    //@ public invariant from != null && to != null;

    /*@ public normal_behavior
      @   requires from != null && to != null;
      @   assignable this.from, this.to;
      @   ensures this.from.equals(from)
      @        && this.to.equals(to);
      @*/
    public ArcType(NodeType from, NodeType to);

    /*@ also
      @   public normal_behavior
      @   {|
      @     requires o instanceof ArcType;
      @     ensures \result
      @        <==> ((ArcType)o).from.equals(from)
      @             && ((ArcType)o).to.equals(to);
      @   also
      @     requires !(o instanceof ArcType);
      @     ensures \result == false;
      @   |}
      @*/
    public boolean equals(/*@ nullable @*/ Object o);

    /*@ also
      @   public normal_behavior
      @     ensures \result instanceof ArcType
      @          && ((ArcType)\result).equals(this);
      @*/
    public Object clone();
}