Source: ../../policy/backend/version_filter.hh
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// -*- c-basic-offset: 4; tab-width: 8; indent-tabs-mode: t -*-
// vim:set sts=4 ts=8:
// Copyright (c) 2001-2008 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/version_filter.hh,v 1.7 2008/10/02 21:58:05 bms Exp $
#ifndef __POLICY_BACKEND_VERSION_FILTER_HH__
#define __POLICY_BACKEND_VERSION_FILTER_HH__
#include "policy/common/varrw.hh"
#include "filter_base.hh"
#include "policy_filter.hh"
/**
* @short Policy filters which support versioning [i.e. keep old version].
*
* The idea is to create a new policy filter on each configuration. Whenever a
* route is being processed, you read which filter to run. If this filter is 0,
* [null pointer] then give it the last configuration. Else just run whatever
* filter is returned.
*
* Filters should be referenced counted by routes. When reference count reaches
* 0, it should be deleted.
*
* Why not keep filters internally here and read a filter id from route? Well
* because we cannot assume when to increment and decrement the reference count.
* Say it's a normal route lookup and we do the filtering, and it results to
* "accepted". It doesn't imply we need to +1 the reference count.
*/
class VersionFilter : public FilterBase {
public:
/**
* @param fname the variable to read/write in order to access filter.
*/
VersionFilter(const VarRW::Id& fname);
~VersionFilter();
/**
* Configure the filter
*
* @param str filter configuration.
*/
void configure(const string& str);
/**
* Reset the filter.
*
* Filter becomes a NO-operation -- default action should
* be returned everytime an acceptRoute is called.
*/
void reset();
/**
* See if a route is accepted by the filter.
* The route may be modified by the filter [through VarRW].
*
* @return true if the route is accepted, false otherwise.
* @param varrw the VarRW associated with the route being filtered.
*/
bool acceptRoute(VarRW& varrw);
private:
RefPf _filter;
VarRW::Id _fname;
};
#endif // __POLICY_BACKEND_VERSION_FILTER_HH__
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