mirror of
https://github.com/boostorg/hana.git
synced 2026-02-23 15:52:11 +00:00
111 lines
3.2 KiB
C++
111 lines
3.2 KiB
C++
/*
|
|
@copyright Louis Dionne 2014
|
|
Distributed under the Boost Software License, Version 1.0.
|
|
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
|
|
*/
|
|
|
|
#include <boost/hana/comparable/equal_mcd.hpp>
|
|
#include <boost/hana/core.hpp>
|
|
#include <boost/hana/detail/constexpr.hpp>
|
|
#include <boost/hana/functional.hpp>
|
|
#include <boost/hana/list/instance.hpp>
|
|
#include <boost/hana/logical/logical.hpp>
|
|
|
|
#include <stdexcept>
|
|
|
|
|
|
namespace boost { namespace hana {
|
|
struct Function;
|
|
|
|
template <typename Domain, typename Codomain, typename F, typename = operators::enable>
|
|
struct function_type {
|
|
using hana_datatype = Function;
|
|
|
|
Domain dom;
|
|
Codomain cod;
|
|
F def;
|
|
|
|
friend constexpr auto domain(function_type f)
|
|
{ return f.dom; }
|
|
|
|
friend constexpr auto codomain(function_type f)
|
|
{ return f.cod; }
|
|
|
|
template <typename X>
|
|
constexpr auto operator()(X x) const {
|
|
if (!any(_ == x, domain(*this)))
|
|
throw std::domain_error{"use of a hana::function with an argument out of the domain"};
|
|
return def(x);
|
|
}
|
|
};
|
|
|
|
BOOST_HANA_CONSTEXPR_LAMBDA auto function = [](auto domain, auto codomain) {
|
|
return [=](auto definition) {
|
|
return function_type<decltype(domain), decltype(codomain), decltype(definition)>{
|
|
domain, codomain, definition
|
|
};
|
|
};
|
|
};
|
|
|
|
BOOST_HANA_CONSTEXPR_LAMBDA auto frange = [](auto f) {
|
|
// Note: that would be better handled by a set data structure, but
|
|
// whatever for now.
|
|
auto insert = [](auto xs, auto x) {
|
|
return if_(any(_ == x, xs), xs, cons(x, xs));
|
|
};
|
|
return foldl(insert, list(), fmap(f, domain(f)));
|
|
};
|
|
|
|
|
|
template <>
|
|
struct Comparable::instance<Function, Function> : Comparable::equal_mcd {
|
|
template <typename F, typename G>
|
|
static constexpr auto equal_impl(F f, G g) {
|
|
return domain(f) == domain(g) && all(demux(_==_, f, g), domain(f));
|
|
}
|
|
};
|
|
}} // end namespace boost::hana
|
|
|
|
|
|
// BOOST_HANA_CONSTEXPR_LAMBDA auto is_injective = [](auto f) {
|
|
// auto check = [](auto x, auto y) {
|
|
// return (x != y) ^implies^ (f(x) != f(y));
|
|
// };
|
|
// return all(check, product(domain(f), domain(f)));
|
|
// };
|
|
|
|
// BOOST_HANA_CONSTEXPR_LAMBDA auto is_onto = [](auto f) {
|
|
// return codomain(f) == range(g);
|
|
// };
|
|
|
|
|
|
#include <boost/hana/detail/static_assert.hpp>
|
|
#include <boost/hana/integral.hpp>
|
|
#include <boost/hana/list/instance.hpp>
|
|
#include <boost/hana/range.hpp>
|
|
using namespace boost::hana;
|
|
using namespace literals;
|
|
|
|
|
|
int main() {
|
|
auto f = function(list(1_c, 2_c, 3_c), list(1_c, 2_c, 3_c, 4_c, 5_c, 6_c))(
|
|
[](auto x) { return x + 1_c; }
|
|
);
|
|
|
|
auto g = function(list(1_c, 2_c, 3_c), list(2_c, 3_c, 4_c))(
|
|
[](auto x) { return x + 1_c; }
|
|
);
|
|
|
|
auto h = function(list(1_c, 2_c, 3_c), list(0_c, 1_c, 2_c))(
|
|
[](auto x) { return x - 1_c; }
|
|
);
|
|
|
|
BOOST_HANA_STATIC_ASSERT(f == g);
|
|
BOOST_HANA_STATIC_ASSERT(f != h);
|
|
BOOST_HANA_STATIC_ASSERT(f(1) == 2);
|
|
try { f(6); throw; } catch (std::domain_error) { }
|
|
|
|
|
|
BOOST_HANA_STATIC_ASSERT(frange(f) == list(4_c, 3_c, 2_c));
|
|
}
|