include/geocel/UnitLength.hh

0001 //------------------------------- -*- C++ -*- -------------------------------//
0002 // Copyright Celeritas contributors: see top-level COPYRIGHT file for details
0003 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
0004 //---------------------------------------------------------------------------//
0005 //! \file geocel/UnitLength.hh
0006 //---------------------------------------------------------------------------//
0007 #pragma once
0008
0009 #include <ostream>
0010
0011 #include "corecel/math/Constant.hh"
0012
0013 #include "detail/LengthUnits.hh"
0014
0015 namespace celeritas
0016 {
0017 //---------------------------------------------------------------------------//
0018 /*!
0019  * Unit system used for reference output or test results.
0020  */
0021 struct UnitLength
0022 {
0023     Constant value{lengthunits::centimeter};
0024     char const* label{"cm"};
0025
0026     template<class T>
0027     constexpr T from_native(T const& v) const
0028     {
0029         return v / value;
0030     }
0031 };
0032
0033 //! Native unit length
0034 inline constexpr UnitLength native_unit_length{Constant{1},
0035                                                lengthunits::native_label};
0036
0037 //---------------------------------------------------------------------------//
0038 /*!
0039  * Print a length/position as a quantity with units.
0040  */
0041 template<class T>
0042 struct StreamableLength
0043 {
0044     T const& native_value;
0045     UnitLength const& units;
0046
0047     friend std::ostream& operator<<(std::ostream& os,
0048                                     StreamableLength const& sl)
0049     {
0050         os << sl.units.from_native(sl.native_value) << " [" << sl.units.label
0051            << ']';
0052         return os;
0053     }
0054 };
0055
0056 //---------------------------------------------------------------------------//
0057 // DEDUCTION GUIDES (C++17)
0058 //---------------------------------------------------------------------------//
0059
0060 template<class T>
0061 StreamableLength(T const&, UnitLength) -> StreamableLength<T>;
0062
0063 //---------------------------------------------------------------------------//
0064 }  // namespace celeritas