Function as_child

boost::proto::as_child — A function that wraps non-Proto expression types in Proto terminals (by reference) and leaves Proto expression types alone.

Synopsis

// In header: <boost/proto/traits.hpp>


template<typename T> 
  typename proto::result_of::as_child< T >::type as_child(T & t);
template<typename T> 
  typename proto::result_of::as_child< T const >::type as_child(T const & t);
template<typename Domain, typename T> 
  typename proto::result_of::as_child< T, Domain >::type as_child(T & t);
template<typename Domain, typename T> 
  typename proto::result_of::as_child< T const, Domain >::type 
  as_child(T const & t);

Description

The proto::as_child() function turns objects into Proto terminals if they are not Proto expression types already. Non-Proto types are held by reference. Types which are already Proto types are simply returned as-is.

This function can be called either with an explicitly specified Domain parameter (i.e., proto::as_child<Domain>(t)), or without (i.e., proto::as_child(t)). If no domain is specified, proto::default_domain is assumed.

If proto::is_expr<T>::value is true, then the argument is returned as-is. Otherwise, proto::as_child() returns Domain()(proto::terminal<T &>::type::make(t)).

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