131 lines
3.5 KiB
C++
131 lines
3.5 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2007 Joel de Guzman
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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_STATEMENT_IF_HPP
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#define PHOENIX_STATEMENT_IF_HPP
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#include <boost/spirit/home/phoenix/core/composite.hpp>
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#include <boost/spirit/home/phoenix/core/as_actor.hpp>
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#include <boost/spirit/home/phoenix/core/compose.hpp>
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#if defined(BOOST_MSVC)
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# pragma warning(push)
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# pragma warning(disable:4355)
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#endif
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namespace boost { namespace phoenix
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{
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struct if_else_eval
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{
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template <typename Env, typename Cond, typename Then, typename Else>
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struct result
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{
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typedef void type;
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};
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template <
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typename RT, typename Env
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, typename Cond, typename Then, typename Else>
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static void
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eval(Env const& env, Cond& cond, Then& then, Else& else_)
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{
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if (cond.eval(env))
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then.eval(env);
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else
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else_.eval(env);
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}
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};
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struct if_eval
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{
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template <typename Env, typename Cond, typename Then>
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struct result
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{
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typedef void type;
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};
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template <typename RT, typename Env, typename Cond, typename Then>
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static void
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eval(Env const& env, Cond& cond, Then& then)
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{
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if (cond.eval(env))
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then.eval(env);
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}
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};
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template <typename Cond, typename Then>
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struct if_composite;
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template <typename Cond, typename Then>
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struct else_gen
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{
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else_gen(if_composite<Cond, Then> const& source)
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: source(source) {}
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template <typename Else>
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actor<typename as_composite<if_else_eval, Cond, Then, Else>::type>
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operator[](Else const& else_) const
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{
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return compose<if_else_eval>(
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fusion::at_c<0>(source) // cond
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, fusion::at_c<1>(source) // then
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, else_ // else
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);
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}
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if_composite<Cond, Then> const& source;
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private:
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// silence MSVC warning C4512: assignment operator could not be generated
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else_gen& operator= (else_gen const&);
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};
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template <typename Cond, typename Then>
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struct if_composite : composite<if_eval, fusion::vector<Cond, Then> >
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{
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if_composite(Cond const& cond, Then const& then)
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: composite<if_eval, fusion::vector<Cond, Then> >(cond, then)
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, else_(*this) {}
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else_gen<Cond, Then> else_;
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private:
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// silence MSVC warning C4512: assignment operator could not be generated
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if_composite& operator= (if_composite const&);
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};
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template <typename Cond>
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struct if_gen
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{
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if_gen(Cond const& cond)
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: cond(cond) {}
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template <typename Then>
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actor<if_composite<Cond, typename as_actor<Then>::type> >
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operator[](Then const& then) const
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{
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return actor<if_composite<Cond, typename as_actor<Then>::type> >(
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cond, as_actor<Then>::convert(then));
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}
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Cond cond;
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};
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template <typename Cond>
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inline if_gen<typename as_actor<Cond>::type>
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if_(Cond const& cond)
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{
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return if_gen<typename as_actor<Cond>::type>(
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as_actor<Cond>::convert(cond));
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}
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}}
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#if defined(BOOST_MSVC)
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# pragma warning(pop)
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#endif
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#endif
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