// -*- c-basic-offset: 4; tab-width: 8; indent-tabs-mode: t -*-
// vim:set sts=4 ts=8:

// Copyright (c) 2001-2009 XORP, Inc.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, Version 2, June
// 1991 as published by the Free Software Foundation. Redistribution
// and/or modification of this program under the terms of any other
// version of the GNU General Public License is not permitted.
// 
// 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. For more details,
// see the GNU General Public License, Version 2, a copy of which can be
// found in the XORP LICENSE.gpl file.
// 
// XORP Inc, 2953 Bunker Hill Lane, Suite 204, Santa Clara, CA 95054, USA;
// http://xorp.net

// $XORP: xorp/policy/backend/instruction_base.hh,v 1.8 2008/10/02 21:58:03 bms Exp $

#ifndef __POLICY_BACKEND_INSTRUCTION_BASE_HH__
#define __POLICY_BACKEND_INSTRUCTION_BASE_HH__

#include "instr_visitor.hh"

/**
 * @short Base class for an instruction.
 *
 * An instruction is an operation a policy filter may execute. Such as pushing
 * an element on the stack.
 */
class Instruction {
public:
    virtual ~Instruction() {}

    /**
     * Pass the current instruction to the visitor.
     *
     * @param v visitor to use on instruction.
     */
    virtual void accept(InstrVisitor& v) = 0;
};

// macro ugliness to make instruction visitable [usable by visitor].
#define INSTR_VISITABLE() \
void accept(InstrVisitor& v) { \
    v.visit(*this); \
}

#endif // __POLICY_BACKEND_INSTRUCTION_BASE_HH__
