Added thirdparty: boost library

thirdparty/include/boost/ratio/ratio.hpp

@@ -0,0 +1,49 @@
+//  ratio.hpp  ---------------------------------------------------------------//
+
+//  Copyright 2008 Howard Hinnant
+//  Copyright 2008 Beman Dawes
+//  Copyright 2009 Vicente J. Botet Escriba
+
+//  Distributed under the Boost Software License, Version 1.0.
+//  See http://www.boost.org/LICENSE_1_0.txt
+
+/*
+
+This code was derived by Beman Dawes from Howard Hinnant's time2_demo prototype.
+Many thanks to Howard for making his code available under the Boost license.
+The original code was modified to conform to Boost conventions and to section
+20.4 Compile-time rational arithmetic [ratio], of the C++ committee working
+paper N2798.
+See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2798.pdf.
+
+time2_demo contained this comment:
+
+    Much thanks to Andrei Alexandrescu,
+                   Walter Brown,
+                   Peter Dimov,
+                   Jeff Garland,
+                   Terry Golubiewski,
+                   Daniel Krugler,
+                   Anthony Williams.
+*/
+
+// The way overflow is managed for ratio_less is taken from llvm/libcxx/include/ratio
+
+#ifndef BOOST_RATIO_RATIO_HPP
+#define BOOST_RATIO_RATIO_HPP
+
+#include <boost/ratio/ratio_fwd.hpp>
+#include <boost/ratio/detail/gcd_lcm.hpp>
+
+namespace boost
+{
+
+// extension used by Chrono
+
+template <class R1, class R2> using ratio_gcd = typename ratio<
+    ratio_detail::gcd<R1::num, R2::num>::value,
+    ratio_detail::lcm<R1::den, R2::den>::value>::type;
+
+}  // namespace boost
+
+#endif  // BOOST_RATIO_RATIO_HPP