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boost::spirit::karma based to_string impl

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This commit is contained in:
Artem Pavlenko 2012-04-19 13:35:41 +01:00
parent 7ae0383a4b
commit 145f83b806
1 changed files with 37 additions and 8 deletions
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45
include/mapnik/util/conversions.hpp
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@ -23,21 +23,50 @@
#ifndef MAPNIK_UTIL_CONVERSIONS_HPP
#define MAPNIK_UTIL_CONVERSIONS_HPP
// mapnik
// stl
#include <string>
// boost
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/karma.hpp>
namespace mapnik { namespace util {
bool string2int(const char * value, int & result);
bool string2int(std::string const& value, int & result);
bool string2int(const char * value, int & result);
bool string2int(std::string const& value, int & result);
bool string2double(std::string const& value, double & result);
bool string2double(const char * value, double & result);
bool string2double(std::string const& value, double & result);
bool string2double(const char * value, double & result);
bool string2float(std::string const& value, float & result);
bool string2float(const char * value, float & result);
bool string2float(std::string const& value, float & result);
bool string2float(const char * value, float & result);
// generic
template <typename T>
bool to_string(std::string & str, T value)
{
namespace karma = boost::spirit::karma;
std::back_insert_iterator<std::string> sink(str);
return karma::generate(sink, value);
}
template <typename T>
struct double_policy : boost::spirit::karma::real_policies<T>
{
typedef boost::spirit::karma::real_policies<T> base_type;
static int floatfield(T n) { return base_type::fmtflags::fixed; }
static unsigned precision(T n) { return 16 ;}
};
// specialisation for double
template <>
inline bool to_string(std::string & str, double value)
{
namespace karma = boost::spirit::karma;
typedef boost::spirit::karma::real_generator<double, double_policy<double> > double_type;
std::back_insert_iterator<std::string> sink(str);
return karma::generate(sink, double_type(), value);
}
}}