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epoc32/include/stdapis/boost/variant/variant_fwd.hpp
author William Roberts <williamr@symbian.org>
Wed, 31 Mar 2010 12:33:34 +0100
branchSymbian3
changeset 4 837f303aceeb
permissions -rw-r--r--
Current Symbian^3 public API header files (from PDK 3.0.h)
This is the epoc32/include tree with the "platform" subtrees removed, and
all but a selected few mbg and rsg files removed. 
     1 //-----------------------------------------------------------------------------

     2 // boost variant/variant_fwd.hpp header file

     3 // See http://www.boost.org for updates, documentation, and revision history.

     4 //-----------------------------------------------------------------------------

     5 //

     6 // Copyright (c) 2003

     7 // Eric Friedman, Itay Maman

     8 //

     9 // Distributed under the Boost Software License, Version 1.0. (See

    10 // accompanying file LICENSE_1_0.txt or copy at

    11 // http://www.boost.org/LICENSE_1_0.txt)

    12 

    13 #ifndef BOOST_VARIANT_VARIANT_FWD_HPP

    14 #define BOOST_VARIANT_VARIANT_FWD_HPP

    15 

    16 #include "boost/variant/detail/config.hpp"

    17 

    18 #include "boost/blank_fwd.hpp"

    19 #include "boost/mpl/arg.hpp"

    20 #include "boost/mpl/limits/arity.hpp"

    21 #include "boost/mpl/aux_/na.hpp"

    22 #include "boost/preprocessor/cat.hpp"

    23 #include "boost/preprocessor/enum.hpp"

    24 #include "boost/preprocessor/enum_params.hpp"

    25 #include "boost/preprocessor/enum_shifted_params.hpp"

    26 #include "boost/preprocessor/repeat.hpp"

    27 

    28 ///////////////////////////////////////////////////////////////////////////////

    29 // macro BOOST_VARIANT_LIMIT_TYPES

    30 //

    31 // Implementation-defined preprocessor symbol describing the actual

    32 // length of variant's pseudo-variadic template parameter list.

    33 //

    34 #include "boost/mpl/limits/list.hpp"

    35 #define BOOST_VARIANT_LIMIT_TYPES \

    36     BOOST_MPL_LIMIT_LIST_SIZE

    37 

    38 ///////////////////////////////////////////////////////////////////////////////

    39 // macro BOOST_VARIANT_NO_REFERENCE_SUPPORT

    40 //

    41 // Defined if variant does not support references as bounded types. 

    42 //

    43 #if defined(BOOST_VARIANT_AUX_BROKEN_CONSTRUCTOR_TEMPLATE_ORDERING) \

    44  && !defined(BOOST_VARIANT_AUX_HAS_CONSTRUCTOR_TEMPLATE_ORDERING_SFINAE_WKND) \

    45  && !defined(BOOST_VARIANT_NO_REFERENCE_SUPPORT)

    46 #   define BOOST_VARIANT_NO_REFERENCE_SUPPORT

    47 #endif

    48 

    49 ///////////////////////////////////////////////////////////////////////////////

    50 // macro BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT

    51 //

    52 // Defined if variant does not support make_variant_over (see below). 

    53 //

    54 #if defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)

    55 #   define BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT

    56 #endif

    57 

    58 ///////////////////////////////////////////////////////////////////////////////

    59 // macro BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT

    60 //

    61 // Defined if make_recursive_variant cannot be supported as documented.

    62 //

    63 // Note: Currently, MPL lambda facility is used as workaround if defined, and

    64 // so only types declared w/ MPL lambda workarounds will work.

    65 //

    66 

    67 #include "boost/variant/detail/substitute_fwd.hpp"

    68 

    69 #if defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE) \

    70  && !defined(BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT)

    71 #   define BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT

    72 #endif

    73 

    74 ///////////////////////////////////////////////////////////////////////////////

    75 // macro BOOST_VARIANT_RECURSIVE_VARIANT_MAX_ARITY

    76 //

    77 // Exposes maximum allowed arity of class templates with recursive_variant

    78 // arguments. That is,

    79 //   make_recursive_variant< ..., T<[1], recursive_variant_, ... [N]> >.

    80 //

    81 #include "boost/mpl/limits/arity.hpp"

    82 #define BOOST_VARIANT_RECURSIVE_VARIANT_MAX_ARITY \

    83     BOOST_MPL_LIMIT_METAFUNCTION_ARITY

    84 

    85 ///////////////////////////////////////////////////////////////////////////////

    86 // macro BOOST_VARIANT_ENUM_PARAMS

    87 //

    88 // Convenience macro for enumeration of BOOST_VARIANT_LIMIT_TYPES params.

    89 //

    90 // Rationale: Cleaner, simpler code for clients of variant library.

    91 //

    92 #define BOOST_VARIANT_ENUM_PARAMS( param )  \

    93     BOOST_PP_ENUM_PARAMS(BOOST_VARIANT_LIMIT_TYPES, param)

    94 

    95 ///////////////////////////////////////////////////////////////////////////////

    96 // macro BOOST_VARIANT_ENUM_SHIFTED_PARAMS

    97 //

    98 // Convenience macro for enumeration of BOOST_VARIANT_LIMIT_TYPES-1 params.

    99 //

   100 #define BOOST_VARIANT_ENUM_SHIFTED_PARAMS( param )  \

   101     BOOST_PP_ENUM_SHIFTED_PARAMS(BOOST_VARIANT_LIMIT_TYPES, param)

   102 

   103 

   104 namespace boost {

   105 

   106 namespace detail { namespace variant {

   107 

   108 ///////////////////////////////////////////////////////////////////////////////

   109 // (detail) class void_ and class template convert_void

   110 // 

   111 // Provides the mechanism by which void(NN) types are converted to

   112 // mpl::void_ (and thus can be passed to mpl::list).

   113 //

   114 // Rationale: This is particularly needed for the using-declarations

   115 // workaround (below), but also to avoid associating mpl namespace with

   116 // variant in argument dependent lookups (which used to happen because of

   117 // defaulting of template parameters to mpl::void_).

   118 //

   119 

   120 struct void_;

   121 

   122 template <typename T>

   123 struct convert_void

   124 {

   125     typedef T type;

   126 };

   127 

   128 template <>

   129 struct convert_void< void_ >

   130 {

   131     typedef mpl::na type;

   132 };

   133 

   134 ///////////////////////////////////////////////////////////////////////////////

   135 // (workaround) BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE

   136 //

   137 // Needed to work around compilers that don't support using-declaration

   138 // overloads. (See the variant::initializer workarounds below.)

   139 //

   140 

   141 #if defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)

   142 

   143 // (detail) tags voidNN -- NN defined on [0, BOOST_VARIANT_LIMIT_TYPES)

   144 //

   145 // Defines void types that are each unique and specializations of

   146 // convert_void that yields mpl::na for each voidNN type.

   147 //

   148 

   149 #define BOOST_VARIANT_DETAIL_DEFINE_VOID_N(z,N,_)          \

   150     struct BOOST_PP_CAT(void,N);                           \

   151                                                            \

   152     template <>                                            \

   153     struct convert_void< BOOST_PP_CAT(void,N) >            \

   154     {                                                      \

   155         typedef mpl::na type;                              \

   156     };                                                     \

   157     /**/

   158 

   159 BOOST_PP_REPEAT(

   160       BOOST_VARIANT_LIMIT_TYPES

   161     , BOOST_VARIANT_DETAIL_DEFINE_VOID_N

   162     , _

   163     )

   164 

   165 #undef BOOST_VARIANT_DETAIL_DEFINE_VOID_N

   166 

   167 #endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround

   168 

   169 }} // namespace detail::variant

   170 

   171 ///////////////////////////////////////////////////////////////////////////////

   172 // (detail) macro BOOST_VARIANT_AUX_DECLARE_PARAM

   173 //

   174 // Template parameter list for variant and recursive_variant declarations.

   175 //

   176 

   177 #if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)

   178 

   179 #   define BOOST_VARIANT_AUX_DECLARE_PARAMS_IMPL(z, N, T) \

   180     typename BOOST_PP_CAT(T,N) = detail::variant::void_ \

   181     /**/

   182 

   183 #else // defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)

   184 

   185 #   define BOOST_VARIANT_AUX_DECLARE_PARAMS_IMPL(z, N, T) \

   186     typename BOOST_PP_CAT(T,N) = BOOST_PP_CAT(detail::variant::void,N) \

   187     /**/

   188 

   189 #endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround

   190 

   191 #define BOOST_VARIANT_AUX_DECLARE_PARAMS \

   192     BOOST_PP_ENUM( \

   193           BOOST_VARIANT_LIMIT_TYPES \

   194         , BOOST_VARIANT_AUX_DECLARE_PARAMS_IMPL \

   195         , T \

   196         ) \

   197     /**/

   198 

   199 ///////////////////////////////////////////////////////////////////////////////

   200 // class template variant (concept inspired by Andrei Alexandrescu)

   201 //

   202 // Efficient, type-safe bounded discriminated union.

   203 //

   204 // Preconditions:

   205 //  - Each type must be unique.

   206 //  - No type may be const-qualified.

   207 //

   208 // Proper declaration form:

   209 //   variant<types>    (where types is a type-sequence)

   210 // or

   211 //   variant<T0,T1,...,Tn>  (where T0 is NOT a type-sequence)

   212 //

   213 template < BOOST_VARIANT_AUX_DECLARE_PARAMS > class variant;

   214 

   215 ///////////////////////////////////////////////////////////////////////////////

   216 // metafunction make_recursive_variant

   217 //

   218 // Exposes a boost::variant with recursive_variant_ tags (below) substituted

   219 // with the variant itself (wrapped as needed with boost::recursive_wrapper).

   220 //

   221 template < BOOST_VARIANT_AUX_DECLARE_PARAMS > struct make_recursive_variant;

   222 

   223 #undef BOOST_VARIANT_AUX_DECLARE_PARAMS_IMPL

   224 #undef BOOST_VARIANT_AUX_DECLARE_PARAMS

   225 

   226 ///////////////////////////////////////////////////////////////////////////////

   227 // type recursive_variant_

   228 //

   229 // Tag type indicates where recursive variant substitution should occur.

   230 //

   231 #if !defined(BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT)

   232     struct recursive_variant_;

   233 #else

   234     typedef mpl::arg<1> recursive_variant_;

   235 #endif

   236 

   237 ///////////////////////////////////////////////////////////////////////////////

   238 // metafunction make_variant_over

   239 //

   240 // Result is a variant w/ types of the specified type sequence.

   241 //

   242 template <typename Types> struct make_variant_over;

   243 

   244 ///////////////////////////////////////////////////////////////////////////////

   245 // metafunction make_recursive_variant_over

   246 //

   247 // Result is a recursive variant w/ types of the specified type sequence.

   248 //

   249 template <typename Types> struct make_recursive_variant_over;

   250 

   251 } // namespace boost

   252 

   253 #endif // BOOST_VARIANT_VARIANT_FWD_HPP
test