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-rw-r--r-- | src/boost/libs/hana/example/integral_constant.cpp | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/integral_constant.cpp b/src/boost/libs/hana/example/integral_constant.cpp new file mode 100644 index 000000000..aaad126da --- /dev/null +++ b/src/boost/libs/hana/example/integral_constant.cpp @@ -0,0 +1,101 @@ +// 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/config.hpp> +#include <boost/hana/equal.hpp> +#include <boost/hana/for_each.hpp> +#include <boost/hana/integral_constant.hpp> +#include <boost/hana/mult.hpp> +#include <boost/hana/negate.hpp> +#include <boost/hana/plus.hpp> +#include <boost/hana/tuple.hpp> + +#include <string> +#include <vector> +namespace hana = boost::hana; + + +int main() { + +{ + +//! [operators] +BOOST_HANA_CONSTANT_CHECK(hana::int_c<1> + hana::int_c<3> == hana::int_c<4>); + +// Mixed-type operations are supported, but only when it involves a +// promotion, and not a conversion that could be lossy. +BOOST_HANA_CONSTANT_CHECK(hana::size_c<3> * hana::ushort_c<5> == hana::size_c<15>); +BOOST_HANA_CONSTANT_CHECK(hana::llong_c<15> == hana::int_c<15>); +//! [operators] + +}{ + +//! [times_loop_unrolling] +std::string s; +for (char c = 'x'; c <= 'z'; ++c) + hana::int_<5>::times([&] { s += c; }); + +BOOST_HANA_RUNTIME_CHECK(s == "xxxxxyyyyyzzzzz"); +//! [times_loop_unrolling] + +}{ + +//! [times_higher_order] +std::string s; +auto functions = hana::make_tuple( + [&] { s += "x"; }, + [&] { s += "y"; }, + [&] { s += "z"; } +); +hana::for_each(functions, hana::int_<5>::times); +BOOST_HANA_RUNTIME_CHECK(s == "xxxxxyyyyyzzzzz"); +//! [times_higher_order] + +}{ + +//! [from_object] +std::string s; +for (char c = 'x'; c <= 'z'; ++c) + hana::int_c<5>.times([&] { s += c; }); + +BOOST_HANA_RUNTIME_CHECK(s == "xxxxxyyyyyzzzzz"); +//! [from_object] + +}{ + +//! [times_with_index_runtime] +std::vector<int> v; +hana::int_<5>::times.with_index([&](auto index) { v.push_back(index); }); + +BOOST_HANA_RUNTIME_CHECK(v == std::vector<int>{0, 1, 2, 3, 4}); +//! [times_with_index_runtime] + +//! [times_with_index_compile_time] +constexpr auto xs = hana::tuple_c<int, 0, 1, 2>; +hana::int_<3>::times.with_index([xs](auto index) { + BOOST_HANA_CONSTANT_CHECK(xs[index] == index); +}); +//! [times_with_index_compile_time] + +}{ + +//! [literals] +using namespace hana::literals; // contains the _c suffix + +BOOST_HANA_CONSTANT_CHECK(1234_c == hana::llong_c<1234>); +BOOST_HANA_CONSTANT_CHECK(-1234_c == hana::llong_c<-1234>); +BOOST_HANA_CONSTANT_CHECK(1_c + (3_c * 4_c) == hana::llong_c<1 + (3 * 4)>); +//! [literals] + +}{ + +//! [integral_c] +BOOST_HANA_CONSTANT_CHECK(hana::integral_c<int, 2> == hana::int_c<2>); +static_assert(decltype(hana::integral_c<int, 2>)::value == 2, ""); +//! [integral_c] + +} + +} |