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Struct template unary_expr

boost::proto::unary_expr — A metafunction for generating unary expression types with a specified tag type, a grammar element for matching unary expressions, and a PrimitiveTransform that dispatches to the proto::pass_through<> transform.


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

template<typename Tag, typename T> 
struct unary_expr :  proto::transform< unary_expr<Tag, T> > {
  // types
  typedef proto::expr< Tag, proto::list1< T > >       type;         
  typedef proto::basic_expr< Tag, proto::list1< T > > proto_grammar;

  // member classes/structs/unions
  template<typename Expr, typename State, typename Data> 
  struct impl :
     proto::pass_through<unary_expr>::template impl<Expr, State, Data>


Use proto::unary_expr<proto::_, proto::_> as a grammar element to match any unary expression.