robot/include/boost/geometry/util/rational.hpp

// Boost.Geometry (aka GGL, Generic Geometry Library)

// Copyright (c) 2011-2012 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2011-2012 Bruno Lalande, Paris, France.
// Copyright (c) 2011-2012 Mateusz Loskot, London, UK.

// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.

// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_GEOMETRY_UTIL_RATIONAL_HPP
#define BOOST_GEOMETRY_UTIL_RATIONAL_HPP

// Contains specializations for Boost.Rational

#include <boost/rational.hpp>

#include <boost/geometry/util/bounds.hpp>
#include <boost/geometry/util/coordinate_cast.hpp>
#include <boost/geometry/util/numeric_cast.hpp>
#include <boost/geometry/util/select_most_precise.hpp>


namespace boost{ namespace geometry
{


// Specialize for Boost.Geometry's coordinate cast
// (from string to coordinate type)
namespace detail
{

template <typename T>
struct coordinate_cast<rational<T> >
{
    static inline void split_parts(std::string const& source, std::string::size_type p,
        T& before, T& after, bool& negate, std::string::size_type& len)
    {
        std::string before_part = source.substr(0, p);
        std::string const after_part = source.substr(p + 1);

        negate = false;

        if (before_part.size() > 0 && before_part[0] == '-')
        {
            negate = true;
            before_part.erase(0, 1);
        }
        before = atol(before_part.c_str());
        after = atol(after_part.c_str());
        len = after_part.length();
    }


    static inline rational<T> apply(std::string const& source)
    {
        T before, after;
        bool negate;
        std::string::size_type len;

        // Note: decimal comma is not (yet) supported, it does (and should) not
        // occur in a WKT, where points are comma separated.
        std::string::size_type p = source.find('.');
        if (p == std::string::npos)
        {
            p = source.find('/');
            if (p == std::string::npos)
            {
                return rational<T>(atol(source.c_str()));
            }
            split_parts(source, p, before, after, negate, len);

            return negate
                ? -rational<T>(before, after)
                : rational<T>(before, after)
                ;

        }

        split_parts(source, p, before, after, negate, len);

        T den = 1;
        for (std::string::size_type i = 0; i < len; i++)
        {
            den *= 10;
        }

        return negate
            ? -rational<T>(before) - rational<T>(after, den)
            : rational<T>(before) + rational<T>(after, den)
            ;
    }
};

} // namespace detail

// Specialize for Boost.Geometry's select_most_precise
template <typename T1, typename T2>
struct select_most_precise<boost::rational<T1>, boost::rational<T2> >
{
    typedef typename boost::rational
        <
            typename select_most_precise<T1, T2>::type
        > type;
};

template <typename T>
struct select_most_precise<boost::rational<T>, double>
{
    typedef typename boost::rational<T> type;
};

namespace util
{

#ifndef DOXYGEN_NO_DETAIL
namespace detail
{

// Specialize numeric_caster, needed for geomery::util::numeric_cast, for Boost.Rational
// Without it, code using Boost.Rational does not compile
template <typename Target, typename T>
struct numeric_caster<Target, rational<T>>
{
   static inline Target apply(rational<T> const& source)
    {
        return boost::rational_cast<Target>(source);
    }
};

} // namespace detail
#endif


// Specializes geometry::util::bounds for Boost.Rational
// Without it, bounds contains (0,1) by default for Boost.Rational
template<class T>
struct bounds<rational<T> >
{
    static inline rational<T> lowest()
    {
        return rational<T>(bounds<T>::lowest(), 1);
    }
    static inline rational<T> highest()
    {
        return rational<T>(bounds<T>::highest(), 1);
    }
};

} // namespace util

}} // namespace boost::geometry


#endif // BOOST_GEOMETRY_UTIL_RATIONAL_HPP