137 lines
3 KiB
C++
137 lines
3 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 EXPRESSION_HPP
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#define EXPRESSION_HPP
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#include "value.hpp"
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#include "filter_visitor.hpp"
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namespace mapnik
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{
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template <typename FeatureT> class filter_visitor;
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template <typename FeatureT>
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struct expression
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{
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virtual value get_value(FeatureT const& feature) const=0;
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virtual void accept(filter_visitor<FeatureT>& v)=0;
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virtual expression<FeatureT>* clone() const=0;
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virtual std::string to_string() const=0;
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virtual ~expression() {}
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};
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template <typename FeatureT>
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class literal : public expression<FeatureT>
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{
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public:
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literal(int val)
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: expression<FeatureT>(),
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value_(val) {}
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literal(double val)
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: expression<FeatureT>(),
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value_(val) {}
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literal(std::string const& val)
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: expression<FeatureT>(),
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value_(val) {}
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literal(literal const& other)
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: expression<FeatureT>(),
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value_(other.value_) {}
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value get_value(FeatureT const& /*feature*/) const
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{
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return value_;
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}
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void accept(filter_visitor<FeatureT>& v)
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{
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v.visit(*this);
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}
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expression<FeatureT>* clone() const
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{
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return new literal(*this);
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}
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std::string to_string() const
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{
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return "'"+value_.to_string()+"'";
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}
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~literal() {}
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private:
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value value_;
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};
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template <typename FeatureT>
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class property : public expression<FeatureT>
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{
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public:
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property(std::string const& name)
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: expression<FeatureT>(),
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name_(name),
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index_(0),
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valid_(false) {}
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property(property const& other)
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: expression<FeatureT>(),
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name_(other.name_),
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index_(other.index_),
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valid_(other.valid_) {}
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value get_value(FeatureT const& feature) const
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{
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if (valid_)
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{
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return feature.get_property(index_);
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}
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else
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{
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return value("");
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}
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}
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void accept(filter_visitor<FeatureT>& v)
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{
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v.visit(*this);
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}
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expression<FeatureT>* clone() const
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{
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return new property(*this);
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}
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std::string const& name() const
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{
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return name_;
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}
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void set_index(size_t index)
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{
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index_=index;
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valid_=true;
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}
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std::string to_string() const
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{
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return "["+name_+"]";
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}
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~property() {}
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private:
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std::string name_;
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size_t index_;
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bool valid_;
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};
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}
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#endif //EXPRESSION_HPP
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