146 lines
4.5 KiB
C++
146 lines
4.5 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2007 Joel de Guzman
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Copyright (c) 2004 Daniel Wallin
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#ifndef PHOENIX_SCOPE_LET_HPP
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#define PHOENIX_SCOPE_LET_HPP
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#include <boost/spirit/home/phoenix/core/limits.hpp>
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#include <boost/spirit/home/phoenix/core/composite.hpp>
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#include <boost/spirit/home/phoenix/scope/scoped_environment.hpp>
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#include <boost/spirit/home/phoenix/scope/detail/local_variable.hpp>
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#include <boost/spirit/home/phoenix/detail/local_reference.hpp>
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#include <boost/spirit/home/phoenix/core/actor.hpp>
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#include <boost/fusion/include/transform.hpp>
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#include <boost/fusion/include/as_vector.hpp>
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#include <boost/mpl/eval_if.hpp>
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#include <boost/mpl/bool.hpp>
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namespace boost { namespace phoenix
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{
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template <typename Base, typename Vars, typename Map>
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struct let_actor : Base
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{
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typedef typename
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mpl::fold<
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Vars
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, mpl::false_
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, detail::compute_no_nullary
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>::type
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no_nullary;
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template <typename Env>
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struct result
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{
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typedef typename
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fusion::result_of::as_vector<
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typename fusion::result_of::transform<
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Vars
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, detail::initialize_local<Env>
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>::type
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>::type
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locals_type;
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typedef typename Base::template
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result<scoped_environment<Env, Env, locals_type, Map> >::type
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result_type;
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typedef typename
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detail::unwrap_local_reference<result_type>::type
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type;
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};
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let_actor(Base const& base, Vars const& vars)
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: Base(base), vars(vars) {}
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template <typename Env>
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typename result<Env>::type
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eval(Env const& env) const
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{
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typedef typename
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fusion::result_of::as_vector<
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typename fusion::result_of::transform<
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Vars
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, detail::initialize_local<Env>
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>::type
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>::type
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locals_type;
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locals_type locals =
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fusion::as_vector(
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fusion::transform(
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vars
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, detail::initialize_local<Env>(env)));
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typedef typename result<Env>::type RT;
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return RT(Base::eval(
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scoped_environment<Env, Env, locals_type, Map>(
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env
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, env
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, locals)));
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}
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Vars vars;
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};
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template <typename Vars, typename Map>
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struct let_actor_gen
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{
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template <typename Base>
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actor<let_actor<Base, Vars, Map> > const
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operator[](actor<Base> const& base) const
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{
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return let_actor<Base, Vars, Map>(base, vars);
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}
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let_actor_gen(Vars const& vars)
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: vars(vars) {}
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Vars vars;
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};
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template <typename Key>
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struct local_variable; // forward
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struct assign_eval; // forward
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struct let_gen
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{
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template <typename K0, typename V0>
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let_actor_gen<
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fusion::vector<V0>
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, detail::map_local_index_to_tuple<K0>
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>
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operator()(
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actor<composite<assign_eval, fusion::vector<local_variable<K0>, V0> > > const& a0
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) const
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{
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return fusion::vector<V0>(fusion::at_c<1>(a0));
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}
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template <typename K0, typename K1, typename V0, typename V1>
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let_actor_gen<
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fusion::vector<V0, V1>
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, detail::map_local_index_to_tuple<K0, K1>
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>
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operator()(
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actor<composite<assign_eval, fusion::vector<local_variable<K0>, V0> > > const& a0
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, actor<composite<assign_eval, fusion::vector<local_variable<K1>, V1> > > const& a1
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) const
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{
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return fusion::vector<V0, V1>(fusion::at_c<1>(a0), fusion::at_c<1>(a1));
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}
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// Bring in the rest...
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#define PHOENIX_LOCAL_GEN_NAME let_actor_gen
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#include <boost/spirit/home/phoenix/scope/detail/local_gen.hpp>
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#undef PHOENIX_LOCAL_GEN_NAME
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};
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let_gen const let = let_gen();
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}}
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#endif
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