[Boost-commit] svn:boost r74147 - trunk/boost/geometry/util

Subject: [Boost-commit] svn:boost r74147 - trunk/boost/geometry/util
From: barend.gehrels_at_[hidden]
Date: 2011-08-30 06:46:35

Author: barendgehrels
Date: 2011-08-30 06:46:34 EDT (Tue, 30 Aug 2011)
New Revision: 74147
URL: http://svn.boost.org/trac/boost/changeset/74147

Log:
Added basic support for Boost.Rational
Added:
   trunk/boost/geometry/util/rational.hpp   (contents, props changed)

Added: trunk/boost/geometry/util/rational.hpp
==============================================================================
--- (empty file)
+++ trunk/boost/geometry/util/rational.hpp	2011-08-30 06:46:34 EDT (Tue, 30 Aug 2011)
@@ -0,0 +1,149 @@
+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2011-2011 Barend Gehrels, Amsterdam, the Netherlands.
+// Copyright (c) 2011-2011 Bruno Lalande, Paris, France.
+// Copyright (c) 2011-2011 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
+
+#include <boost/rational.hpp>
+#include <boost/numeric/conversion/bounds.hpp>
+
+#include <boost/geometry/util/coordinate_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 rational<T> apply(std::string const& source)
+    {
+        // 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 const p = source.find(".");
+        if (p == std::string::npos)
+        {
+            return rational<T>(atol(source.c_str()));
+        }
+
+        std::string const natural_part = source.substr(0, p);
+        std::string const fraction = source.substr(p + 1);
+
+        T const nat = atol(natural_part.c_str());
+        T const nom = atol(fraction.c_str());
+        T den = 1;
+        for (std::string::size_type i = 0; i < fraction.length(); i++)
+        {
+            den *= 10;
+        }
+
+        return rational<T>(nat) + rational<T>(nom, 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 boost::geometry
+
+
+// Specializes boost::rational to boost::numeric::bounds
+namespace boost { namespace numeric 
+{
+
+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 boost::numeric
+
+
+// Support for boost::numeric_cast to int and to double (necessary for SVG-mapper)
+namespace boost { namespace numeric
+{
+
+template
+<
+    typename T,
+    typename Traits,
+    typename OverflowHandler,
+    typename Float2IntRounder,
+    typename RawConverter,
+    typename UserRangeChecker
+>
+struct converter<int, rational<T>, Traits, OverflowHandler, Float2IntRounder, RawConverter, UserRangeChecker>
+{
+    static inline int convert(rational<T> const& arg)
+    {
+        double v = arg.numerator();
+        v /= arg.denominator();
+        return int(v);
+    }
+};
+
+template
+<
+    typename T,
+    typename Traits,
+    typename OverflowHandler,
+    typename Float2IntRounder,
+    typename RawConverter,
+    typename UserRangeChecker
+>
+struct converter<double, rational<T>, Traits, OverflowHandler, Float2IntRounder, RawConverter, UserRangeChecker>
+{
+    static inline double convert(rational<T> const& arg)
+    {
+        double v = arg.numerator();
+        v /= arg.denominator();
+        return v;
+    }
+};
+
+
+}}
+
+
+#endif // BOOST_GEOMETRY_UTIL_RATIONAL_HPP