You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and dots ('.'), can be up to 35 characters long. Letters must be lowercase.
165 lines
4.4 KiB
165 lines
4.4 KiB
/*============================================================================== |
|
Copyright (c) 2001-2010 Joel de Guzman |
|
Copyright (c) 2010 Eric Niebler |
|
|
|
Distributed under the Boost Software License, Version 1.0. (See accompanying |
|
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
|
==============================================================================*/ |
|
#ifndef BOOST_PHOENIX_STATEMENT_IF_HPP |
|
#define BOOST_PHOENIX_STATEMENT_IF_HPP |
|
|
|
#include <boost/config.hpp> |
|
#include <boost/phoenix/core/limits.hpp> |
|
#include <boost/phoenix/core/actor.hpp> |
|
#include <boost/phoenix/core/call.hpp> |
|
#include <boost/phoenix/core/expression.hpp> |
|
#include <boost/phoenix/core/meta_grammar.hpp> |
|
#include <boost/phoenix/core/is_actor.hpp> |
|
|
|
#ifdef BOOST_MSVC |
|
#pragma warning(push) |
|
#pragma warning(disable: 4355) // 'this' used in base member initializer list |
|
#endif |
|
|
|
namespace boost { namespace phoenix |
|
{ |
|
template <typename> struct if_actor; |
|
}} |
|
|
|
BOOST_PHOENIX_DEFINE_EXPRESSION_EXT( |
|
if_actor |
|
, (boost)(phoenix)(if_) |
|
, (meta_grammar) // Cond |
|
(meta_grammar) // Then |
|
) |
|
|
|
BOOST_PHOENIX_DEFINE_EXPRESSION( |
|
(boost)(phoenix)(if_else_statement) |
|
, (meta_grammar) // Cond |
|
(meta_grammar) // Then |
|
(meta_grammar) // Else |
|
) |
|
|
|
namespace boost { namespace phoenix |
|
{ |
|
//////////////////////////////////////////////////////////////////////////// |
|
// If-Else statements |
|
//////////////////////////////////////////////////////////////////////////// |
|
|
|
// Function for evaluating lambdas like: |
|
// if_( foo )[ bar ] |
|
// and |
|
// if_( foo )[ bar ].else_[ baz ] |
|
struct if_else_eval |
|
{ |
|
typedef void result_type; |
|
|
|
template<typename Cond, typename Then, typename Context> |
|
result_type |
|
operator()(Cond const & cond, Then const & then, Context & ctx) const |
|
{ |
|
if(boost::phoenix::eval(cond, ctx)) |
|
boost::phoenix::eval(then, ctx); |
|
} |
|
|
|
template<typename Cond, typename Then, typename Else, typename Context> |
|
result_type |
|
operator()( |
|
Cond const & cond |
|
, Then const & then |
|
, Else const & else_ |
|
, Context const & ctx |
|
) const |
|
{ |
|
if(boost::phoenix::eval(cond, ctx)) |
|
boost::phoenix::eval(then, ctx); |
|
else |
|
boost::phoenix::eval(else_, ctx); |
|
} |
|
}; |
|
|
|
template <typename Dummy> |
|
struct default_actions::when<rule::if_, Dummy> |
|
: call<if_else_eval, Dummy> |
|
{}; |
|
|
|
template <typename Dummy> |
|
struct default_actions::when<rule::if_else_statement, Dummy> |
|
: call<if_else_eval, Dummy> |
|
{}; |
|
|
|
|
|
// Generator for .else_[ expr ] branch. |
|
template<typename Cond, typename Then> |
|
struct else_gen |
|
{ |
|
else_gen(Cond const & cond, Then const & then) |
|
: cond(cond) |
|
, then(then) {} |
|
|
|
template<typename Else> |
|
typename expression::if_else_statement<Cond, Then, Else>::type const |
|
operator[](Else const & else_) const |
|
{ |
|
return expression::if_else_statement<Cond, Then, Else>::make(cond, then, else_); |
|
} |
|
|
|
Cond cond; |
|
Then then; |
|
}; |
|
|
|
// We subclass actor so we can provide the member else_ (which is an |
|
// else_gen responsible for the .else_[ expr ] branch). |
|
template<typename Expr> |
|
struct if_actor : actor<Expr> |
|
{ |
|
typedef actor<Expr> base_type; |
|
|
|
if_actor(base_type const & base) |
|
: base_type(base) |
|
, else_(proto::child_c<0>(*this), proto::child_c<1>(*this)) |
|
{} |
|
|
|
typedef typename proto::result_of::child_c<Expr, 0>::type cond_type; |
|
typedef typename proto::result_of::child_c<Expr, 1>::type then_type; |
|
|
|
else_gen<cond_type, then_type> else_; |
|
}; |
|
|
|
template <typename Expr> |
|
struct is_actor<if_actor<Expr> > |
|
: mpl::true_ |
|
{}; |
|
|
|
// Generator for if( cond )[ then ] branch. |
|
template<typename Cond> |
|
struct if_gen |
|
{ |
|
if_gen(Cond const & cond) |
|
: cond(cond) {} |
|
|
|
template<typename Then> |
|
typename expression::if_<Cond, Then>::type const |
|
operator[](Then const & then) const |
|
{ |
|
return expression::if_<Cond, Then>::make(cond, then); |
|
} |
|
|
|
Cond cond; |
|
}; |
|
|
|
template<typename Cond> |
|
inline |
|
if_gen<Cond> const |
|
if_(Cond const & cond) |
|
{ |
|
return if_gen<Cond>(cond); |
|
} |
|
|
|
}} |
|
|
|
#ifdef BOOST_MSVC |
|
#pragma warning(pop) |
|
#endif |
|
|
|
#endif
|
|
|