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Struct template child

boost::proto::functional::child — A callable PolymorphicFunctionObject that is equivalent to the proto::child() function.

Synopsis

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

template<typename N = mpl::long_<0> > 
struct child :  proto::callable {
  template<typename This, typename Expr> 
  struct result<This(Expr)> :  proto::result_of::child< Expr, N > {
  };

  // public member functions
  template<typename Expr> 
    typename proto::result_of::child< Expr &, N >::type 
    operator()(Expr &) const;
  template<typename Expr> 
    typename proto::result_of::child< Expr const &, N >::type 
    operator()(Expr const &) const;
};

Description

A callable PolymorphicFunctionObject that is equivalent to the proto::child() function. N is required to be an MPL Integral Constant.

child public member functions

  1. template<typename Expr> 
      typename proto::result_of::child< Expr &, N >::type 
      operator()(Expr & expr) const;

    Return the Nth child of the given expression.

    Parameters:

    expr

    The expression node.

    Requires:

    proto::is_expr<Expr>::value is true

    N::value < Expr::proto_arity::value

    Returns:

    proto::child<N>(expr)

    Throws:

    Will not throw.
  2. template<typename Expr> 
      typename proto::result_of::child< Expr const &, N >::type 
      operator()(Expr const & expr) const;

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.


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