66 lines
1.7 KiB
C++
66 lines
1.7 KiB
C++
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/* This file is part of Mapnik (c++ mapping toolkit)
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* Copyright (C) 2005 Artem Pavlenko
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*
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* Mapnik is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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//$Id$
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#ifndef FILTER_HPP
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#define FILTER_HPP
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#include "filter_visitor.hpp"
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#include "feature.hpp"
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namespace mapnik
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{
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typedef ref_ptr<filter<Feature> > filter_ptr;
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template <typename FeatureT> class filter_visitor;
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template <typename FeatureT>
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struct filter
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{
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virtual bool pass(const FeatureT& feature) const=0;
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virtual filter<FeatureT>* clone() const=0;
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virtual void accept(filter_visitor<FeatureT>& v) = 0;
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virtual std::string to_string() const=0;
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virtual ~filter() {}
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};
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template <typename FeatureT>
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struct null_filter : public filter<FeatureT>
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{
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bool pass (const FeatureT&) const
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{
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return true;
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}
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filter<FeatureT>* clone() const
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{
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return new null_filter<FeatureT>;
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}
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std::string to_string() const
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{
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return "true";
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}
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void accept(filter_visitor<FeatureT>&) {}
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virtual ~null_filter() {}
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};
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}
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#endif //FILTER_HPP
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