:relfileprefix: ../../../
[#FEFD73EAB578C47CDFA48BA9DFDC8E4953A67A21]

= Class is_rule



== Synopsis

Declared in header `</boost/url/grammar/type_traits.hpp#L54[boost/url/grammar/type_traits.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
template<class T>
struct xref:boost/urls/grammar/is_rule-0a.adoc[is_rule]<T, xref:boost/urls/void_t.adoc[void_t]<decltype(std::declval<system::result<typename T::value_type>&>() =
                std::declval<T const&>().parse(
                    std::declval<char const*&>(),
                    std::declval<char const*>()))>>
    : xref:std.adoc[std]::xref:std/is_nothrow_copy_constructible.adoc[is_nothrow_copy_constructible]<T>;
----