68 lines
2.4 KiB
C++
68 lines
2.4 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) 2014 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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#ifndef MAPNIK_EXPRESSION_STRING_HPP
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#define MAPNIK_EXPRESSION_STRING_HPP
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// mapnik
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#include <mapnik/config.hpp>
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#include <mapnik/function_call.hpp>
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#include <mapnik/expression_node_types.hpp>
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// boost
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#include <memory>
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// stl
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#include <string>
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#include <stdexcept>
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namespace mapnik
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{
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MAPNIK_DECL std::string to_expression_string(expr_node const& node);
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/*
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The following two templates are intentionally invalid and will prompt
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a compile error if ever instantiated. This should prevent accidentally
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passing a pointer (either raw or shared) as the argument. Without them,
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the compiler could construct a temporary expr_node(bool) using
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implicit pointer-to-bool conversion, thus any non-null pointer
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would yield "true".
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*/
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template <typename T>
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std::string to_expression_string(T const* expr_node_ptr)
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{
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throw std::logic_error("to_expression_string() called with pointer argument");
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// compile error intended here; comment on the next line shows in clang output
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return expr_node_ptr; // to_expression_string() called with pointer argument
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}
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template <typename T>
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std::string to_expression_string(std::shared_ptr<T> const& expr_node_ptr)
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{
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throw std::logic_error("to_expression_string() called with pointer argument");
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// compile error intended here; comment on the next line shows in clang output
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return expr_node_ptr; // to_expression_string() called with pointer argument
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}
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}
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#endif // MAPNIK_EXPRESSION_STRING_HPP
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