boost/contract/base_types.hpp

   1
   2 #ifndef BOOST_CONTRACT_BASE_TYPES_HPP_
   3 #define BOOST_CONTRACT_BASE_TYPES_HPP_
   4
   5 // Copyright (C) 2008-2018 Lorenzo Caminiti
   6 // Distributed under the Boost Software License, Version 1.0 (see accompanying
   7 // file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
   8 // See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
   9
  10 /** @file
  11 Specify inheritance form base classes (for subcontracting).
  12 */
  13
  14 // IMPORTANT: Included by contract_macro.hpp so must #if-guard all its includes.
  15 #include <boost/contract/core/config.hpp>
  16 #include <boost/preprocessor/config/config.hpp>
  17
  18 #ifdef BOOST_CONTRACT_DETAIL_DOXYGEN
  19
  20 /**
  21 Used to program the @c typedef that lists the bases of a derived class.
  22
  23 In order to support subcontracting, a derived class that specifies contracts for
  24 one or more overriding public functions must declare a @c typedef named
  25 @c base_types (or @RefMacro{BOOST_CONTRACT_BASES_TYPEDEF}) using this macro:
  26
  27     @code
  28         class u
  29             #define BASES public b, protected virtual w1, private w2
  30             : BASES
  31         {
  32             friend class boost::contract:access;
  33
  34             typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
  35             #undef BASES
  36
  37             ...
  38         };
  39     @endcode
  40
  41 This @c typedef must be @c public unless @RefClass{boost::contract::access} is
  42 used.
  43
  44 @see @RefSect{tutorial.base_classes__subcontracting_, Base Classes}
  45
  46 @param ...  Comma separated list of base classes.
  47             Each base must explicitly specify its access specifier @c public,
  48             @c protected, or @c private, and also @c virtual when present
  49             (this not always required in C++ instead).
  50             There is a limit of about 20 maximum bases that can be listed
  51             (because of similar limits in Boost.MPL internally used by this
  52             library).
  53             This is a variadic macro parameter, on compilers that do not support
  54             variadic macros, the @c typedef for base classes can be programmed
  55             manually without using this macro (see
  56             @RefSect{extras.no_macros__and_no_variadic_macros_, No Macros}).
  57
  58 */
  59 #define BOOST_CONTRACT_BASE_TYPES(...)
  60
  61 #elif !BOOST_PP_VARIADICS
  62
  63 #define BOOST_CONTRACT_BASE_TYPES \
  64 BOOST_CONTRACT_ERROR_macro_BASE_TYPES_requires_variadic_macros_otherwise_manually_program_base_types
  65
  66 #elif !defined(BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS)
  67
  68 #include <boost/mpl/vector.hpp>
  69 #include <boost/contract/detail/preprocessor/keyword/virtual.hpp>
  70 #include <boost/contract/detail/preprocessor/keyword/public.hpp>
  71 #include <boost/contract/detail/preprocessor/keyword/protected.hpp>
  72 #include <boost/contract/detail/preprocessor/keyword/private.hpp>
  73 #include <boost/preprocessor/variadic/to_seq.hpp>
  74 #include <boost/preprocessor/seq/fold_left.hpp>
  75 #include <boost/preprocessor/seq/enum.hpp>
  76 #include <boost/preprocessor/seq/push_back.hpp>
  77 #include <boost/preprocessor/seq/size.hpp>
  78 #include <boost/preprocessor/seq/seq.hpp> // For HEAD, TAIL, etc.
  79 #include <boost/preprocessor/tuple/elem.hpp>
  80 #include <boost/preprocessor/tuple/rem.hpp>
  81 #include <boost/preprocessor/tuple/eat.hpp>
  82 #include <boost/preprocessor/comparison/equal.hpp>
  83 #include <boost/preprocessor/control/iif.hpp>
  84 #include <boost/preprocessor/facilities/expand.hpp>
  85
  86 /* PRIVATE */
  87
  88 #define BOOST_CONTRACT_BASE_TYPES_REMOVE_VIRTUAL_(base) \
  89     BOOST_PP_EXPAND( \
  90         BOOST_PP_IIF(BOOST_CONTRACT_DETAIL_PP_KEYWORD_IS_VIRTUAL(base), \
  91             BOOST_CONTRACT_DETAIL_PP_KEYWORD_REMOVE_VIRTUAL \
  92         , \
  93             BOOST_PP_TUPLE_REM(1) \
  94         )(base) \
  95     )
  96
  97 #define BOOST_CONTRACT_BASE_TYPES_PUSH_BACK_IF_(is_public, types_nilseq, base) \
  98     ( \
  99         is_public, \
 100         BOOST_PP_IIF(is_public, \
 101             BOOST_PP_SEQ_PUSH_BACK \
 102         , \
 103             types_nilseq BOOST_PP_TUPLE_EAT(2) \
 104         )(types_nilseq, base) \
 105     )
 106
 107 #define BOOST_CONTRACT_BASE_TYPES_SKIP_NOT_PUBLIC_(is_public, types_nilseq, \
 108         base) \
 109     (0, types_nilseq)
 110
 111 // Precondition: base = `public [virtual] ...`.
 112 #define BOOST_CONTRACT_BASE_TYPES_PUSH_BACK_PUBLIC_(is_public, types_nilseq, \
 113         base) \
 114     ( \
 115         1, \
 116         BOOST_PP_SEQ_PUSH_BACK(types_nilseq, \
 117             BOOST_CONTRACT_BASE_TYPES_REMOVE_VIRTUAL_( \
 118                     BOOST_CONTRACT_DETAIL_PP_KEYWORD_REMOVE_PUBLIC(base)) \
 119         ) \
 120     )
 121
 122 #define BOOST_CONTRACT_BASE_TYPES_ACCESS_(is_public, types_nilseq, base) \
 123     BOOST_PP_IIF(BOOST_CONTRACT_DETAIL_PP_KEYWORD_IS_PUBLIC(base), \
 124         BOOST_CONTRACT_BASE_TYPES_PUSH_BACK_PUBLIC_ \
 125     , BOOST_PP_IIF(BOOST_CONTRACT_DETAIL_PP_KEYWORD_IS_PROTECTED(base), \
 126         BOOST_CONTRACT_BASE_TYPES_SKIP_NOT_PUBLIC_ \
 127     , BOOST_PP_IIF(BOOST_CONTRACT_DETAIL_PP_KEYWORD_IS_PRIVATE(base), \
 128         BOOST_CONTRACT_BASE_TYPES_SKIP_NOT_PUBLIC_ \
 129     , \
 130         BOOST_CONTRACT_BASE_TYPES_PUSH_BACK_IF_ \
 131     )))(is_public, types_nilseq, base)
 132
 133 #define BOOST_CONTRACT_BASE_TYPES_(s, public_types, base) \
 134     BOOST_CONTRACT_BASE_TYPES_ACCESS_( \
 135         BOOST_PP_TUPLE_ELEM(2, 0, public_types), \
 136         BOOST_PP_TUPLE_ELEM(2, 1, public_types), \
 137         BOOST_CONTRACT_BASE_TYPES_REMOVE_VIRTUAL_(base) \
 138     )
 139
 140 #define BOOST_CONTRACT_BASE_TYPES_RETURN_YES_(types_nilseq) \
 141     BOOST_PP_SEQ_ENUM(BOOST_PP_SEQ_TAIL(types_nilseq))
 142
 143 #define BOOST_CONTRACT_BASE_TYPES_RETURN_(types_nilseq) \
 144     BOOST_PP_IIF(BOOST_PP_EQUAL(BOOST_PP_SEQ_SIZE(types_nilseq), 1), \
 145         BOOST_PP_TUPLE_EAT(1) \
 146     , \
 147         BOOST_CONTRACT_BASE_TYPES_RETURN_YES_ \
 148     )(types_nilseq)
 149
 150 #define BOOST_CONTRACT_BASE_TYPES_OK_(base_tuple, bases_seq) \
 151     boost::mpl::vector< \
 152         BOOST_CONTRACT_BASE_TYPES_RETURN_(BOOST_PP_TUPLE_ELEM(2, 1, \
 153             BOOST_PP_SEQ_FOLD_LEFT( \
 154                 BOOST_CONTRACT_BASE_TYPES_, \
 155                 (0, (BOOST_PP_NIL)), \
 156                 bases_seq \
 157             ) \
 158         )) \
 159     >
 160
 161 #define BOOST_CONTRACT_BASE_TYPES_ERR_(bases_tuple, bases_seq) \
 162     BOOST_CONTRACT_ERROR_all_bases_must_explicitly_specify_public_protected_or_private base_tuple
 163
 164 #define BOOST_CONTRACT_BASE_TYPES_IS_ACCESS_(base) \
 165     BOOST_PP_IIF(BOOST_CONTRACT_DETAIL_PP_KEYWORD_IS_PUBLIC(base), \
 166         1 \
 167     , BOOST_PP_IIF(BOOST_CONTRACT_DETAIL_PP_KEYWORD_IS_PROTECTED(base), \
 168         1 \
 169     , BOOST_PP_IIF(BOOST_CONTRACT_DETAIL_PP_KEYWORD_IS_PRIVATE(base), \
 170         1 \
 171     , \
 172         0 \
 173     )))
 174
 175 // Cannot check that all base types have access specifiers (unless users have to
 176 // specify bases using pp-seq, because user specified base list can have
 177 // unwrapped commas between bases but also within a given base type, when base
 178 // types are templates), but at least check the very first base type explicitly
 179 // specifies access `[virtual] public | protected | private [virtual] ...`.
 180 #define BOOST_CONTRACT_BASE_TYPES_CHECK_(bases_tuple, bases_seq) \
 181     BOOST_PP_IIF(BOOST_CONTRACT_BASE_TYPES_IS_ACCESS_( \
 182             BOOST_CONTRACT_BASE_TYPES_REMOVE_VIRTUAL_(BOOST_PP_SEQ_HEAD( \
 183                     bases_seq))), \
 184         BOOST_CONTRACT_BASE_TYPES_OK_ \
 185     , \
 186         BOOST_CONTRACT_BASE_TYPES_ERR_ \
 187     )(bases_tuple, bases_seq)
 188
 189 /* PUBLIC */
 190
 191 #define BOOST_CONTRACT_BASE_TYPES(...) \
 192     BOOST_CONTRACT_BASE_TYPES_CHECK_((__VA_ARGS__), \
 193             BOOST_PP_VARIADIC_TO_SEQ(__VA_ARGS__))
 194
 195 #else
 196
 197 #define BOOST_CONTRACT_BASE_TYPES(...) void /* dummy type for typedef */
 198
 199 #endif
 200
 201 #endif // #include guard
 202