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      1 
      2 #ifndef BOOST_MPL_EVAL_IF_HPP_INCLUDED
      3 #define BOOST_MPL_EVAL_IF_HPP_INCLUDED
      4 
      5 // Copyright Aleksey Gurtovoy 2000-2004
      6 //
      7 // Distributed under the Boost Software License, Version 1.0.
      8 // (See accompanying file LICENSE_1_0.txt or copy at
      9 // http://www.boost.org/LICENSE_1_0.txt)
     10 //
     11 // See http://www.boost.org/libs/mpl for documentation.
     12 
     13 // $Id: eval_if.hpp 61921 2010-05-11 21:33:24Z neilgroves $
     14 // $Date: 2010-05-11 14:33:24 -0700 (Tue, 11 May 2010) $
     15 // $Revision: 61921 $
     16 
     17 #include <boost/mpl/if.hpp>
     18 #include <boost/mpl/aux_/na_spec.hpp>
     19 #include <boost/mpl/aux_/lambda_support.hpp>
     20 #include <boost/mpl/aux_/config/msvc.hpp>
     21 #include <boost/mpl/aux_/config/gcc.hpp>
     22 #include <boost/mpl/aux_/config/workaround.hpp>
     23 
     24 namespace boost { namespace mpl {
     25 
     26 template<
     27       typename BOOST_MPL_AUX_NA_PARAM(C)
     28     , typename BOOST_MPL_AUX_NA_PARAM(F1)
     29     , typename BOOST_MPL_AUX_NA_PARAM(F2)
     30     >
     31 struct eval_if
     32 #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) \
     33      || ( BOOST_WORKAROUND(BOOST_MPL_CFG_GCC, >= 0x0300) \
     34         && BOOST_WORKAROUND(BOOST_MPL_CFG_GCC, BOOST_TESTED_AT(0x0304)) \
     35         )
     36 {
     37     typedef typename if_<C,F1,F2>::type f_;
     38     typedef typename f_::type type;
     39 #else
     40     : if_<C,F1,F2>::type
     41 {
     42 #endif
     43     BOOST_MPL_AUX_LAMBDA_SUPPORT(3,eval_if,(C,F1,F2))
     44 };
     45 
     46 // (almost) copy & paste in order to save one more
     47 // recursively nested template instantiation to user
     48 template<
     49       bool C
     50     , typename F1
     51     , typename F2
     52     >
     53 struct eval_if_c
     54 #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) \
     55      || ( BOOST_WORKAROUND(BOOST_MPL_CFG_GCC, >= 0x0300) \
     56         && BOOST_WORKAROUND(BOOST_MPL_CFG_GCC, BOOST_TESTED_AT(0x0304)) \
     57         )
     58 {
     59     typedef typename if_c<C,F1,F2>::type f_;
     60     typedef typename f_::type type;
     61 #else
     62     : if_c<C,F1,F2>::type
     63 {
     64 #endif
     65 };
     66 
     67 BOOST_MPL_AUX_NA_SPEC(3, eval_if)
     68 
     69 }}
     70 
     71 #endif // BOOST_MPL_EVAL_IF_HPP_INCLUDED
     72