ceph/src/boost/libs/metaparse/example/meta_hs/bind.hpp

   1 #ifndef META_HS_BIND_HPP
   2 #define META_HS_BIND_HPP
   3
   4 // Copyright Abel Sinkovics (abel@sinkovics.hu)  2012.
   5 // Distributed under the Boost Software License, Version 1.0.
   6 //    (See accompanying file LICENSE_1_0.txt or copy at
   7 //          http://www.boost.org/LICENSE_1_0.txt)
   8
   9 #include <lazy.hpp>
  10 #include <ast.hpp>
  11
  12 #include <boost/mpl/at.hpp>
  13 #include <boost/mpl/insert.hpp>
  14 #include <boost/mpl/pair.hpp>
  15
  16 template <class AST, class TopEnv, class Env>
  17 struct bind;
  18
  19 template <class V, class TopEnv, class Env>
  20 struct bind<ast::value<V>, TopEnv, Env>
  21 {
  22   typedef lazy::value<V> type;
  23 };
  24
  25 template <class Name, class TopEnv, class Env>
  26 struct bind<ast::ref<Name>, TopEnv, Env> :
  27   bind<typename boost::mpl::at<Env, Name>::type, TopEnv, Env>
  28 {};
  29
  30 template <class F, class Arg, class TopEnv, class Env>
  31 struct bind<ast::application<F, Arg>, TopEnv, Env>
  32 {
  33   typedef
  34     lazy::application<
  35       typename bind<F, TopEnv, Env>::type,
  36       typename bind<Arg, TopEnv, Env>::type
  37     >
  38     type;
  39 };
  40
  41 template <class F, class ArgName, class TopEnv, class Env>
  42 struct bind<ast::lambda<F, ArgName>, TopEnv, Env>
  43 {
  44   typedef bind type;
  45
  46   template <class ArgValue>
  47   struct apply :
  48     bind<
  49       F,
  50       TopEnv,
  51       typename boost::mpl::insert<
  52         Env,
  53         boost::mpl::pair<ArgName, ast::value<ArgValue> >
  54       >::type
  55     >::type
  56   {};
  57 };
  58
  59 template <class E, class TopEnv, class Env>
  60 struct bind<ast::top_bound<E>, TopEnv, Env> : bind<E, TopEnv, TopEnv> {};
  61
  62 #endif
  63