diff options
Diffstat (limited to 'boost/hana/string.hpp')
| -rw-r--r-- | boost/hana/string.hpp | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/boost/hana/string.hpp b/boost/hana/string.hpp index f9f6cae8e9..a7b83dee86 100644 --- a/boost/hana/string.hpp +++ b/boost/hana/string.hpp @@ -13,6 +13,7 @@ Distributed under the Boost Software License, Version 1.0. #include <boost/hana/fwd/string.hpp> #include <boost/hana/bool.hpp> +#include <boost/hana/concept/constant.hpp> #include <boost/hana/config.hpp> #include <boost/hana/core/make.hpp> #include <boost/hana/detail/algorithm.hpp> @@ -148,6 +149,35 @@ BOOST_HANA_NAMESPACE_BEGIN }; ////////////////////////////////////////////////////////////////////////// + // to<string_tag> + ////////////////////////////////////////////////////////////////////////// + namespace detail { + constexpr std::size_t cx_strlen(char const* s) { + std::size_t n = 0u; + while (*s != '\0') + ++s, ++n; + return n; + } + + template <typename S, std::size_t ...I> + constexpr hana::string<hana::value<S>()[I]...> expand(std::index_sequence<I...>) + { return {}; } + } + + template <typename IC> + struct to_impl<hana::string_tag, IC, hana::when< + hana::Constant<IC>::value && + std::is_convertible<typename IC::value_type, char const*>::value + >> { + template <typename S> + static constexpr auto apply(S const&) { + constexpr char const* s = hana::value<S>(); + constexpr std::size_t len = detail::cx_strlen(s); + return detail::expand<S>(std::make_index_sequence<len>{}); + } + }; + + ////////////////////////////////////////////////////////////////////////// // Comparable ////////////////////////////////////////////////////////////////////////// template <> |