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
83