hana/example/core/convert/embedding.cpp
2017-01-07 14:14:18 -08:00

37 lines
1.0 KiB
C++

// Copyright Louis Dionne 2013-2017
// 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/assert.hpp>
#include <boost/hana/core/to.hpp>
#include <boost/hana/core/when.hpp>
#include <vector>
namespace hana = boost::hana;
namespace boost { namespace hana {
template <typename To, typename From>
struct to_impl<std::vector<To>, std::vector<From>,
when<is_convertible<From, To>::value>>
: embedding<is_embedded<From, To>::value>
{
static std::vector<To> apply(std::vector<From> const& xs) {
std::vector<To> result;
for (auto const& x: xs)
result.push_back(to<To>(x));
return result;
}
};
}}
int main() {
BOOST_HANA_RUNTIME_CHECK(
hana::to<std::vector<int>>(std::vector<float>{1.1, 2.2, 3.3})
==
std::vector<int>{1, 2, 3}
);
static_assert(!hana::is_embedded<std::vector<float>, std::vector<int>>{}, "");
}