/*
 * This source code is released into the public domain.
 */

module;

#include <concepts>
#include <locale>

export module nihil:ctype;

namespace nihil {

/*
 * ctype_is: wrap std::ctype<T>::is() in a form suitable for use as an algorithm
 * predicate, i.e., ctype_is(m) will return a functor object that takes any char
 * type as an argument and returns bool.
 *
 * If the locale is not specified, the current global locale is used by default.
 *
 * ctype_is copies the locale, so passing a temporary is fine.
 */

export struct ctype_is final {
	ctype_is(std::ctype_base::mask mask_,
		 std::locale const &locale_ = std::locale())
	    : mask(mask_)
	    , locale(locale_)
	{}

	auto operator()(this ctype_is const &self, std::integral auto c)
	{
		using ctype = std::ctype<decltype(c)>;
		auto &facet = std::use_facet<ctype>(self.locale);
		return facet.is(self.mask, c);
	}

private:
	std::ctype_base::mask mask;
	std::locale locale;
};

// Predefined tests for the current global locale. 

export inline auto is_space = ctype_is(std::ctype_base::space);
export inline auto is_print = ctype_is(std::ctype_base::print);
export inline auto is_cntrl = ctype_is(std::ctype_base::cntrl);
export inline auto is_upper = ctype_is(std::ctype_base::upper);
export inline auto is_lower = ctype_is(std::ctype_base::lower);
export inline auto is_alpha = ctype_is(std::ctype_base::alpha);
export inline auto is_digit = ctype_is(std::ctype_base::digit);
export inline auto is_punct = ctype_is(std::ctype_base::punct);
export inline auto is_xdigit = ctype_is(std::ctype_base::xdigit);
export inline auto is_blank = ctype_is(std::ctype_base::blank);
export inline auto is_alnum = ctype_is(std::ctype_base::alnum);
export inline auto is_graph = ctype_is(std::ctype_base::graph);

// Predefined tests for the C locale.  The C locale is guaranteed to always be
// available, so this doesn't create lifetime issues.

export inline auto is_c_space =
	ctype_is(std::ctype_base::space, std::locale::classic());
export inline auto is_c_print =
	ctype_is(std::ctype_base::print, std::locale::classic());
export inline auto is_c_cntrl =
	ctype_is(std::ctype_base::cntrl, std::locale::classic());
export inline auto is_c_upper =
	ctype_is(std::ctype_base::upper, std::locale::classic());
export inline auto is_c_lower =
	ctype_is(std::ctype_base::lower, std::locale::classic());
export inline auto is_c_alpha =
	ctype_is(std::ctype_base::alpha, std::locale::classic());
export inline auto is_c_digit =
	ctype_is(std::ctype_base::digit, std::locale::classic());
export inline auto is_c_punct =
	ctype_is(std::ctype_base::punct, std::locale::classic());
export inline auto is_c_xdigit =
	ctype_is(std::ctype_base::xdigit, std::locale::classic());
export inline auto is_c_blank =
	ctype_is(std::ctype_base::blank, std::locale::classic());
export inline auto is_c_alnum =
	ctype_is(std::ctype_base::alnum, std::locale::classic());
export inline auto is_c_graph =
	ctype_is(std::ctype_base::graph, std::locale::classic());

} // namespace nihil