ceph/src/boost/libs/proto/include/boost/proto/detail/remove_typename.hpp

   1 //==============================================================================
   2 //         Copyright 2003 - 2011  LASMEA UMR 6602 CNRS/Univ. Clermont II
   3 //         Copyright 2009 - 2011  LRI    UMR 8623 CNRS/Univ Paris Sud XI
   4 //         Copyright 2011         Eric Niebler
   5 //
   6 //          Distributed under the Boost Software License, Version 1.0.
   7 //                 See accompanying file LICENSE.txt or copy at
   8 //                     http://www.boost.org/LICENSE_1_0.txt
   9 //==============================================================================
  10 #ifndef BOOST_PROTO_PREPROCESSOR_REMOVE_TYPENAME_HPP_INCLUDED
  11 #define BOOST_PROTO_PREPROCESSOR_REMOVE_TYPENAME_HPP_INCLUDED
  12
  13 /*!
  14  * \file
  15  * \brief Defines the BOOST_PROTO_REMOVE_TYPENAME macro
  16  */
  17 #include <boost/preprocessor/cat.hpp>
  18 #include <boost/preprocessor/expand.hpp>
  19 #include <boost/preprocessor/tuple/eat.hpp>
  20 #include <boost/preprocessor/control/iif.hpp>
  21 #include <boost/preprocessor/detail/is_unary.hpp>
  22
  23 //==============================================================================
  24 // Boost.Preprocessor author P. Mensodines confirmed on an Boost email thread
  25 // (subject ``check if a token is a keyword (was "BOOST_PP_IS_UNARY()")'')
  26 // that it is OK to used `PP_IS_UNARY()` to check if tokens match predefined
  27 // "keyword" as it is done by the macros below (even if `PP_IS_UNARY()` is
  28 // technically only part of Boost.Preprocessor private API).
  29 //==============================================================================
  30
  31 //==============================================================================
  32 // `checking_prefix ## tokens` expand to unary (e.g., `(1)`) iff `tokens` start
  33 // with keyword to check.
  34 //==============================================================================
  35 #define BOOST_PROTO_DETAILS_KEYWORD_FACILITY_IS_FRONT(T, CHECKING_PREFIX)                           \
  36     BOOST_PP_IS_UNARY(BOOST_PP_CAT(CHECKING_PREFIX, T))                                             \
  37     /**/
  38
  39 //==============================================================================
  40 // `is_front_macro(tokens)` is 1 iff `tokens` start with keyword to remove.
  41 // `removing_prefix ## <keyword-to-remove>` must expand to nothing.
  42 //==============================================================================
  43 #define BOOST_PROTO_DETAILS_KEYWORD_FACILITY_REMOVE_FRONT(TOKENS, IS_FRONT_MACRO, REMOVING_PREFIX)  \
  44     BOOST_PP_EXPAND( /* without EXPAND doesn't expand on MSVC */                                    \
  45         BOOST_PP_IIF(                                                                               \
  46             IS_FRONT_MACRO(TOKENS)                                                                  \
  47           , BOOST_PP_CAT                                                                            \
  48           , TOKENS BOOST_PP_TUPLE_EAT(2)                                                            \
  49         )(REMOVING_PREFIX, TOKENS)                                                                  \
  50     )                                                                                               \
  51     /**/
  52
  53 #define BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_IS_typename (1) /* unary */
  54 #define typename_BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_IS (1) /* unary */
  55 #define BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_REMOVE_typename /* nothing */
  56 #define typename_BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_REMOVE /* nothing */
  57
  58 #define BOOST_PROTO_DETAILS_KEYWORD_IS_TYPENAME_FRONT(TOKENS)                                       \
  59     BOOST_PROTO_DETAILS_KEYWORD_FACILITY_IS_FRONT(TOKENS, BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_IS_) \
  60     /**/
  61
  62 //==============================================================================
  63 /*!
  64  * \ingroup preprocessor
  65  * For any symbol \c X, this macro returns the same symbol from which a potential
  66  * leading \c typename keyword has been removed. If no typename keyword is present,
  67  * this macros evaluates to \c X itself without error.
  68  *
  69  * The original implementation of this macro is from Lorenzo Caminiti.
  70  *
  71  * \param X Symbol to remove \c typename from
  72  */
  73 //==============================================================================
  74 #define BOOST_PROTO_REMOVE_TYPENAME(X)                                                              \
  75     BOOST_PROTO_DETAILS_KEYWORD_FACILITY_REMOVE_FRONT(                                              \
  76         X                                                                                           \
  77       , BOOST_PROTO_DETAILS_KEYWORD_IS_TYPENAME_FRONT                                               \
  78       , BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_REMOVE_                                                \
  79     )                                                                                               \
  80     /**/
  81
  82 #endif