boost/detail/scoped_enum_emulation.hpp

   1 //  scoped_enum_emulation.hpp  ---------------------------------------------------------//
   2
   3 //  Copyright Beman Dawes, 2009
   4
   5 //  Distributed under the Boost Software License, Version 1.0.
   6 //  See http://www.boost.org/LICENSE_1_0.txt
   7
   8 //  Generates C++0x scoped enums if the feature is present, otherwise emulates C++0x
   9 //  scoped enums with C++03 namespaces and enums. The Boost.Config BOOST_NO_SCOPED_ENUMS
  10 //  macro is used to detect feature support.
  11 //
  12 //  See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a
  13 //  description of the scoped enum feature. Note that the committee changed the name
  14 //  from strongly typed enum to scoped enum.
  15 //
  16 //  Caution: only the syntax is emulated; the semantics are not emulated and
  17 //  the syntax emulation doesn't include being able to specify the underlying
  18 //  representation type.
  19 //
  20 //  The emulation is via struct rather than namespace to allow use within classes.
  21 //  Thanks to Andrey Semashev for pointing that out.
  22 //
  23 //  Helpful comments and suggestions were also made by Kjell Elster, Phil Endecott,
  24 //  Joel Falcou, Mathias Gaunard, Felipe Magno de Almeida, Matt Calabrese, Vincente
  25 //  Botet, and Daniel James.
  26 //
  27 //  Sample usage:
  28 //
  29 //     BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END
  30 //     ...
  31 //     BOOST_SCOPED_ENUM(algae) sample( algae::red );
  32 //     void foo( BOOST_SCOPED_ENUM(algae) color );
  33 //     ...
  34 //     sample = algae::green;
  35 //     foo( algae::cyan );
  36
  37 #ifndef BOOST_SCOPED_ENUM_EMULATION_HPP
  38 #define BOOST_SCOPED_ENUM_EMULATION_HPP
  39
  40 #include <boost/config.hpp>
  41
  42 #ifdef BOOST_NO_SCOPED_ENUMS
  43
  44 # define BOOST_SCOPED_ENUM_START(name) struct name { enum enum_t
  45 # define BOOST_SCOPED_ENUM_END };
  46 # define BOOST_SCOPED_ENUM(name) name::enum_t
  47
  48 #else
  49
  50 # define BOOST_SCOPED_ENUM_START(name) enum class name
  51 # define BOOST_SCOPED_ENUM_END
  52 # define BOOST_SCOPED_ENUM(name) name
  53
  54 #endif
  55
  56 #endif  // BOOST_SCOPED_ENUM_EMULATION_HPP