452 lines
12 KiB
C++
452 lines
12 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2006 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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//$Id$
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#ifndef VALUE_HPP
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#define VALUE_HPP
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// stl
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#include <iostream>
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#include <string>
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#include <sstream>
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// boost
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#include <boost/variant.hpp>
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namespace mapnik {
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typedef boost::variant<int,double,std::string> value_base;
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namespace impl {
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struct equals
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: public boost::static_visitor<bool>
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{
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template <typename T, typename U>
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bool operator() (const T &, const U & ) const
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{
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return false;
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}
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template <typename T>
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bool operator() (T lhs, T rhs) const
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{
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return lhs == rhs;
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}
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bool operator() (int lhs, double rhs) const
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{
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return lhs == rhs;
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}
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bool operator() (double lhs, int rhs) const
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{
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return lhs == rhs;
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}
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bool operator() (std::string const& lhs,
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std::string const& rhs) const
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{
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return lhs == rhs;
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}
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};
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struct greater_than
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: public boost::static_visitor<bool>
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{
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template <typename T, typename U>
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bool operator()( const T &, const U & ) const
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{
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return false;
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}
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template <typename T>
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bool operator()( T lhs, T rhs ) const
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{
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return lhs > rhs;
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}
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bool operator() (int lhs, double rhs) const
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{
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return lhs > rhs;
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}
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bool operator() (double lhs, int rhs) const
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{
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return lhs > rhs;
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}
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bool operator() (std::string const& lhs, std::string const& rhs) const
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{
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return lhs > rhs;
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}
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};
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struct greater_or_equal
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: public boost::static_visitor<bool>
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{
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template <typename T, typename U>
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bool operator()( const T &, const U & ) const
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{
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return false;
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}
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template <typename T>
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bool operator() (T lhs, T rhs) const
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{
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return lhs >= rhs;
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}
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bool operator() (int lhs, double rhs) const
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{
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return lhs >= rhs;
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}
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bool operator() (double lhs, int rhs) const
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{
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return lhs >= rhs;
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}
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bool operator() (std::string const& lhs, std::string const& rhs ) const
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{
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return lhs >= rhs;
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}
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};
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struct less_than
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: public boost::static_visitor<bool>
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{
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template <typename T, typename U>
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bool operator()( const T &, const U & ) const
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{
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return false;
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}
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template <typename T>
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bool operator()( T lhs,T rhs) const
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{
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return lhs < rhs;
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}
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bool operator() (int lhs, double rhs) const
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{
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return lhs < rhs;
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}
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bool operator() (double lhs, int rhs) const
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{
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return lhs < rhs;
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}
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bool operator()( std::string const& lhs,
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std::string const& rhs ) const
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{
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return lhs < rhs;
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}
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};
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struct less_or_equal
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: public boost::static_visitor<bool>
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{
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template <typename T, typename U>
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bool operator()( const T &, const U & ) const
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{
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return false;
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}
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template <typename T>
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bool operator()(T lhs, T rhs ) const
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{
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return lhs <= rhs;
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}
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bool operator() (int lhs, double rhs) const
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{
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return lhs <= rhs;
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}
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bool operator() (double lhs, int rhs) const
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{
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return lhs <= rhs;
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}
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template <typename T>
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bool operator()( std::string const& lhs,
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std::string const& rhs ) const
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{
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return lhs <= rhs;
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}
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};
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template <typename V>
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struct add : public boost::static_visitor<V>
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{
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typedef V value_type;
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template <typename T1, typename T2>
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value_type operator() (T1 const& lhs, T2 const&) const
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{
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return lhs;
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}
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template <typename T>
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value_type operator() (T lhs, T rhs) const
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{
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return lhs + rhs ;
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}
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value_type operator() (std::string const& lhs ,
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std::string const& rhs ) const
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{
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return lhs + rhs;
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}
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value_type operator() (double lhs, int rhs) const
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{
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return lhs + rhs;
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}
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value_type operator() (int lhs, double rhs) const
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{
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return lhs + rhs;
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}
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};
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template <typename V>
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struct sub : public boost::static_visitor<V>
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{
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typedef V value_type;
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template <typename T1, typename T2>
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value_type operator() (T1 const& lhs, T2 const&) const
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{
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return lhs;
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}
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template <typename T>
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value_type operator() (T lhs, T rhs) const
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{
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return lhs - rhs ;
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}
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value_type operator() (std::string const& lhs,
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std::string const& ) const
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{
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return lhs;
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}
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value_type operator() (double lhs, int rhs) const
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{
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return lhs - rhs;
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}
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value_type operator() (int lhs, double rhs) const
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{
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return lhs - rhs;
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}
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};
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template <typename V>
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struct mult : public boost::static_visitor<V>
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{
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typedef V value_type;
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template <typename T1, typename T2>
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value_type operator() (T1 const& lhs , T2 const& ) const
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{
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return lhs;
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}
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template <typename T>
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value_type operator() (T lhs, T rhs) const
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{
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return lhs * rhs;
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}
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value_type operator() (std::string const& lhs,
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std::string const& ) const
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{
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return lhs;
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}
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value_type operator() (double lhs, int rhs) const
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{
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return lhs * rhs;
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}
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value_type operator() (int lhs, double rhs) const
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{
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return lhs * rhs;
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}
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};
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template <typename V>
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struct div: public boost::static_visitor<V>
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{
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typedef V value_type;
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template <typename T1, typename T2>
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value_type operator() (T1 const& lhs, T2 const&) const
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{
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return lhs;
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}
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template <typename T>
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value_type operator() (T lhs, T rhs) const
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{
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return lhs / rhs;
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}
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value_type operator() (std::string const& lhs,
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std::string const&) const
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{
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return lhs;
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}
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value_type operator() (double lhs, int rhs) const
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{
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return lhs / rhs;
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}
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value_type operator() (int lhs, double rhs) const
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{
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return lhs / rhs;
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}
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};
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struct to_string : public boost::static_visitor<std::string>
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{
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template <typename T>
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std::string operator() (T val) const
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{
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std::stringstream ss;
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ss << val;
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return ss.str();
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}
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std::string const& operator() (std::string const& val) const
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{
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return val;
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}
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};
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struct to_expression_string : public boost::static_visitor<std::string>
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{
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template <typename T>
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std::string operator() (T val) const
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{
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std::stringstream ss;
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ss << val;
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return ss.str();
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}
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std::string operator() (std::string const& val) const
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{
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return "'" + val + "'";
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}
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};
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}
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class value
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{
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value_base base_;
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friend const value operator+(value const&,value const&);
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friend const value operator-(value const&,value const&);
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friend const value operator*(value const&,value const&);
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friend const value operator/(value const&,value const&);
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public:
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value ()
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: base_(0) {}
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template <typename T> value(T _val_)
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: base_(_val_) {}
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bool operator==(value const& other) const
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{
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return boost::apply_visitor(impl::equals(),base_,other.base_);
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}
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bool operator!=(value const& other) const
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{
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return !(boost::apply_visitor(impl::equals(),base_,other.base_));
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}
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bool operator>(value const& other) const
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{
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return boost::apply_visitor(impl::greater_than(),base_,other.base_);
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}
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bool operator>=(value const& other) const
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{
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return boost::apply_visitor(impl::greater_or_equal(),base_,other.base_);
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}
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bool operator<(value const& other) const
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{
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return boost::apply_visitor(impl::less_than(),base_,other.base_);
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}
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bool operator<=(value const& other) const
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{
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return boost::apply_visitor(impl::less_or_equal(),base_,other.base_);
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}
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value_base const& base() const
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{
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return base_;
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}
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std::string to_expression_string() const
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{
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return boost::apply_visitor(impl::to_expression_string(),base_);
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}
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std::string to_string() const
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{
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return boost::apply_visitor(impl::to_string(),base_);
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}
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};
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inline const value operator+(value const& p1,value const& p2)
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{
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return value(boost::apply_visitor(impl::add<value>(),p1.base_, p2.base_));
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}
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inline const value operator-(value const& p1,value const& p2)
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{
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return value(boost::apply_visitor(impl::sub<value>(),p1.base_, p2.base_));
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}
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inline const value operator*(value const& p1,value const& p2)
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{
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return value(boost::apply_visitor(impl::mult<value>(),p1.base_, p2.base_));
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}
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inline const value operator/(value const& p1,value const& p2)
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{
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return value(boost::apply_visitor(impl::div<value>(),p1.base_, p2.base_));
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}
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template <typename charT, typename traits>
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inline std::basic_ostream<charT,traits>&
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operator << (std::basic_ostream<charT,traits>& out,
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value const& v)
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{
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out << v.base();
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return out;
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}
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}
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#endif //VALUE_HPP
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