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imagerie/boost/math/tools/convert_from_string.hpp

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+//  Copyright John Maddock 2016.
+//  Use, modification and distribution are 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_MATH_TOOLS_CONVERT_FROM_STRING_INCLUDED
+#define BOOST_MATH_TOOLS_CONVERT_FROM_STRING_INCLUDED
+
+#ifdef _MSC_VER
+#pragma once
+#endif
+
+#include <boost/type_traits/is_constructible.hpp>
+#include <boost/type_traits/conditional.hpp>
+#include <boost/lexical_cast.hpp>
+
+namespace boost{ namespace math{ namespace tools{
+
+   template <class T>
+   struct convert_from_string_result
+   {
+      typedef typename boost::conditional<boost::is_constructible<T, const char*>::value, const char*, T>::type type;
+   };
+
+   template <class Real>
+   Real convert_from_string(const char* p, const mpl::false_&)
+   {
+#ifdef BOOST_MATH_NO_LEXICAL_CAST
+      // This function should not compile, we don't have the necesary functionality to support it:
+      BOOST_STATIC_ASSERT(sizeof(Real) == 0);
+#else
+      return boost::lexical_cast<Real>(p);
+#endif
+   }
+   template <class Real>
+   BOOST_CONSTEXPR const char* convert_from_string(const char* p, const mpl::true_&) BOOST_NOEXCEPT
+   {
+      return p;
+   }
+   template <class Real>
+   BOOST_CONSTEXPR typename convert_from_string_result<Real>::type convert_from_string(const char* p) BOOST_NOEXCEPT_IF((boost::is_constructible<Real, const char*>::value))
+   {
+      return convert_from_string<Real>(p, boost::is_constructible<Real, const char*>());
+   }
+
+} // namespace tools
+} // namespace math
+} // namespace boost
+
+#endif // BOOST_MATH_TOOLS_CONVERT_FROM_STRING_INCLUDED
+