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    1 //macros to generate CTOR forwarding methods
    2 #ifndef BOOST_MANAGED_PTR_PP_CTOR_FORWARDER_HPP_LJE20040327
    3 #define BOOST_MANAGED_PTR_PP_CTOR_FORWARDER_HPP_LJE20040327
    4 #include <boost/preprocessor/arithmetic/inc.hpp>
    5 #include <boost/preprocessor/cat.hpp>
    6 #include <boost/preprocessor/control/iif.hpp>
    7 #include <boost/preprocessor/punctuation/comma_if.hpp>
    8 #include <boost/preprocessor/repetition/enum.hpp>
    9 #include <boost/preprocessor/repetition/enum_params.hpp>
   10 #include <boost/preprocessor/repetition/enum_trailing_params.hpp>
   11 #include <boost/preprocessor/repetition/repeat.hpp>
   12 #include <boost/preprocessor/seq/elem.hpp>
   13 #include <boost/preprocessor/seq/fold_right.hpp>
   14 #include <boost/preprocessor/seq/rest_n.hpp>
   15 #include <boost/preprocessor/tuple/rem.hpp>
   16 #include <boost/mpl/vector.hpp>
   17 #include <boost/mpl/at.hpp>
   18 
   19 #define MANAGED_PTR_CTOR_FORWARDER_MAX_ARGS 3
   20 #define FORWARDER_TYPE_PARAM(z, n, _) \
   21         typename boost::mpl::at_c<VecOfTypes, n>::type BOOST_PP_CAT(a, n) \
   22         /**/
   23 //Macro:
   24 //  FORWARDER_TUPLE
   25 //Purpose:
   26 //  Generate a 1 element tuple containing a pair.
   27 #define FORWARDER_TUPLE(s, arg_tuple, name) \
   28         (name arg_tuple) \
   29         /**/
   30 #define FORWARDER_TRGT(z, arity, pass_signature, target_seq) \
   31         : \
   32         BOOST_PP_TUPLE_REM_CTOR( \
   33                 1, \
   34                 BOOST_PP_SEQ_FOLD_RIGHT( \
   35                         FORWARDER_TUPLE, \
   36                         ( BOOST_PP_IIF(pass_signature, signature BOOST_PP_ENUM_TRAILING_PARAMS_Z, \
   37                           BOOST_PP_ENUM_PARAMS_Z)(z, arity, a) \
   38                         ), \
   39                         target_seq \
   40                 ) \
   41         ) { } \
   42         /**/
   43 //Macro:
   44 //  MANAGED_PTR_CTOR_FORWARDER_SRC_TRGT(z, arity, pass_signature, source, target_seq)
   45 //
   46 //  Where:
   47 //  {
   48 //
   49 //     z is the "next available repetition depth" as defined for the BOOST_PP_REPEAT
   50 //       macro argument.
   51 //
   52 //     arity >= 0 and is the number of arguments passed to targetn (see target_seq)
   53 //
   54 //     pass_signature := 0 or 1 and is flag indicating whether targetn takes a signature.
   55 //
   56 //     source = a class name, this is the class which passes the arguments on.
   57 //
   58 //     target_seq :=
   59 //       (target0)(target1)...(targetn)
   60 //       where:
   61 //       { n >= 1
   62 //       }
   63 //
   64 //  }
   65 //
   66 //Purpose:
   67 //  Generate templated constructors with arity+1 arguments for source.
   68 //  The first argument to CTOR specifies the types of the remaining arguments.
   69 //  This 1st arg can be a boost::mpl::vector<T1,...Tarity> const&.
   70 //
   71 //Requires:
   72 //    BOOST_PP_SEQ_SIZE(target_seq) >= 1
   73 //
   74 //Example1:
   75 //  For arity=2, pass_signature=0, source=src, target_seq=(tgt0)(tgt1)(tgt2)
   76 //  generated ctor is:
   77 //
   78 //    template<typename VecOfTypes>
   79 //    src(VecOfTypes const& signature
   80 //      , boost::mpl::at_c<VecOfTypes,0>::type a0
   81 //      , boost::mpl::at_c<VecOfTypes,1>::type a1
   82 //      )
   83 //      :tgt0(tgt1(tgt2(a0,a1))
   84 //    {}
   85 //
   86 //  If pass_signature=1, then the tgt line would be:
   87 //
   88 //      :tgt0(tgt1(tgt2(signature,a0,a1)))
   89 //
   90 #define FORWARDER_SRC_TRGT(z, arity, pass_signature, source, target_seq) \
   91         template<typename VecOfTypes> source( \
   92                 VecOfTypes const& signature BOOST_PP_COMMA_IF(arity) \
   93                 BOOST_PP_ENUM_ ## z(arity, FORWARDER_TYPE_PARAM, ~) \
   94         ) \
   95         FORWARDER_TRGT(z,  arity, pass_signature, target_seq) \
   96         /**/
   97 #define FORWARDER_OVERLOAD_REMAP(z, arity, seq) \
   98         FORWARDER_SRC_TRGT(z, BOOST_PP_INC(arity), BOOST_PP_SEQ_ELEM(0, seq), \
   99           BOOST_PP_SEQ_ELEM(1, seq), BOOST_PP_SEQ_REST_N(2, seq) \
  100         ) \
  101         /**/
  102 //Macro:
  103 //  MANAGED_PTR_CTOR_FORWARDER_OVERLOAD(max_arity, source, target_seq, pass_signature)
  104 //Purpose:
  105 //  Invoke
  106 //    MANAGED_PTR_CTOR_FORWARDER_SRC_TRGT(z, arity, name_seq, pass_signature) for arity=0,max_arity
  107 //Acknowledgements:
  108 //  Special thanks to Paul Mensonides who generously provided all this code
  109 //  in response to:
  110 //
  111 //    http://article.gmane.org/gmane.comp.lib.boost.devel/35348
  112 //
  113 #define MANAGED_PTR_CTOR_FORWARDER_OVERLOAD(max_arity, source, target_seq, pass_signature ) \
  114         template<typename ZeroArgs>source( \
  115                 boost::mpl::vector<ZeroArgs> const& signature \
  116         ) \
  117         FORWARDER_TRGT(2,  0, pass_signature, target_seq) \
  118         BOOST_PP_REPEAT(max_arity, FORWARDER_OVERLOAD_REMAP, (pass_signature)(source)target_seq ) \
  119         /**/
  120 #endif
  121