Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::proto::make::impl
template<typename Expr, typename State, typename Data> struct impl : proto::transform_impl< Expr, State, Data > { // types typedef see-below result_type; // public member functions result_type operator()(typename impl::expr_param, typename impl::state_param, typename impl::data_param) const; };
impl
public
typestypedef see-below result_type;
proto::make<T>::impl<Expr, State, Data>::result_type is
computed as follows:
If T is an ObjectTransform of the form
Object(T0,...TN), then let O be
the return type Object. Otherwise, let O
be T. The result_type typedef is
then computed as follows:
O is a template like
S<X0,...XN>, then the result type is calculated as follows:
For each X in
X0,...XN, let X' be
proto::make<X>::impl<Expr, State, Data>::result_type
(which evaluates this procedure recursively). Note whether any substitutions took place during
this operation.
If any substitutions took place in the above step and
S<X0',...XN'> has a nested
type typedef, the result type is
S<X0',...XN'>::type.
Otherwise, the result type is
S<X0',...XN'>.
Otherwise, if O is a Transform, then let
the result type be
when<_, O>::impl<Expr, State, Data>::result_type
.
Note that a substitution took place.
O, and note that no
substitution took place.
Note that proto::when<> is implemented
in terms of proto::call<>
and proto::make<>, so the
above procedure is evaluated recursively.
impl public member functionsresult_type operator()(typename impl::expr_param expr, typename impl::state_param state, typename impl::data_param data) const;
proto::make<T>::impl<Expr,State,Data>::operator() behaves as follows:
If T if of the form
O(T0,...TN), then:
If
is proto::is_aggregate<result_type>::value
true, then construct
and return an object that as follows:
result_type that = {
proto::when<_, T0>()(expr, state, data),
...
proto::when<_, TN>()(expr, state, data)
};
Otherwise, construct
and return an object that as follows:
result_type that( proto::when<_, T0>()(expr, state, data), ... proto::when<_, TN>()(expr, state, data) );
Otherwise, construct
and return an object that as follows:
result_type that = result_type();