diff options
Diffstat (limited to 'boost/hana/detail/struct_macros.hpp.erb')
| -rw-r--r-- | boost/hana/detail/struct_macros.hpp.erb | 52 |
1 files changed, 49 insertions, 3 deletions
diff --git a/boost/hana/detail/struct_macros.hpp.erb b/boost/hana/detail/struct_macros.hpp.erb index b3675e82af..ecfd0edd69 100644 --- a/boost/hana/detail/struct_macros.hpp.erb +++ b/boost/hana/detail/struct_macros.hpp.erb @@ -7,15 +7,18 @@ export MAX_NUMBER_OF_MEMBERS=55; erb struct_macros.hpp.erb - 'MAX_NUMBER_OF_MEMBERS' must be <= 62, otherwise an error is triggered. - In case 'MAX_NUMBER_OF_MEMBERS' is not specified, it defaults to 40. + 'MAX_NUMBER_OF_MEMBERS' must be greater than 0. In case 'MAX_NUMBER_OF_MEMBERS' + is not specified, it defaults to 40. To regenerate the default struct macros, + issue the following command from the root of the project: + + erb include/boost/hana/detail/struct_macros.hpp.erb > include/boost/hana/detail/struct_macros.hpp [1]: http://en.wikipedia.org/wiki/ERuby %> <% MAX_NUMBER_OF_MEMBERS = (ENV["MAX_NUMBER_OF_MEMBERS"] || 40).to_i - raise "MAX_NUMBER_OF_MEMBERS must be <= 62" if MAX_NUMBER_OF_MEMBERS > 62 + raise "MAX_NUMBER_OF_MEMBERS must be > 0" if not MAX_NUMBER_OF_MEMBERS > 0 %> /*! @@ -76,6 +79,49 @@ BOOST_HANA_NAMESPACE_BEGIN namespace struct_detail { } BOOST_HANA_NAMESPACE_END ////////////////////////////////////////////////////////////////////////////// +// BOOST_HANA_PP_NARG +////////////////////////////////////////////////////////////////////////////// +//! @ingroup group-details +//! Macro expanding to the number of arguments it is passed. +//! +//! Specifically, `BOOST_HANA_PP_NARG(x1, ..., xn)` expands to `n`. It is +//! an error to call this macro with 0 arguments. +#define BOOST_HANA_PP_NARG(...) \ + BOOST_HANA_PP_NARG_IMPL(__VA_ARGS__, <%= (1..MAX_NUMBER_OF_MEMBERS).to_a.reverse.join(',') %>,) + +#define BOOST_HANA_PP_NARG_IMPL(<%= (1..MAX_NUMBER_OF_MEMBERS).to_a.map { |i| "e#{i}" }.join(',') %>, N, ...) N + +////////////////////////////////////////////////////////////////////////////// +// BOOST_HANA_PP_BACK +////////////////////////////////////////////////////////////////////////////// +//! @ingroup group-details +//! Expands to its last argument. +#define BOOST_HANA_PP_BACK(...) \ + BOOST_HANA_PP_BACK_IMPL(BOOST_HANA_PP_NARG(__VA_ARGS__), __VA_ARGS__) + +#define BOOST_HANA_PP_BACK_IMPL(N, ...) \ + BOOST_HANA_PP_CONCAT(BOOST_HANA_PP_BACK_IMPL_, N)(__VA_ARGS__) + +<% (1..MAX_NUMBER_OF_MEMBERS).each do |n| %> +#define BOOST_HANA_PP_BACK_IMPL_<%= n %>(<%= (1..n).to_a.map { |i| "e#{i}" }.join(', ') %>) e<%= n %> +<% end %> + +////////////////////////////////////////////////////////////////////////////// +// BOOST_HANA_PP_DROP_BACK +////////////////////////////////////////////////////////////////////////////// +//! @ingroup group-details +//! Expands to all of its arguments, except for the last one. +#define BOOST_HANA_PP_DROP_BACK(...) \ + BOOST_HANA_PP_DROP_BACK_IMPL(BOOST_HANA_PP_NARG(__VA_ARGS__), __VA_ARGS__) + +#define BOOST_HANA_PP_DROP_BACK_IMPL(N, ...) \ + BOOST_HANA_PP_CONCAT(BOOST_HANA_PP_DROP_BACK_IMPL_, N)(__VA_ARGS__) + +<% (1..MAX_NUMBER_OF_MEMBERS).each do |n| %> +#define BOOST_HANA_PP_DROP_BACK_IMPL_<%= n %>(<%= (1..n).to_a.map { |i| "e#{i}" }.join(', ') %>)<%= (1..n-1).to_a.map { |i| "e#{i}" }.join(', ') %> +<% end %> + +////////////////////////////////////////////////////////////////////////////// // BOOST_HANA_ADAPT_STRUCT ////////////////////////////////////////////////////////////////////////////// template <typename ...> |