[Tuple] Add examples and slightly improve tests

example/tuple.cpp

@@ -0,0 +1,79 @@
+/*
+@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/assert.hpp>
+#include <boost/hana/detail/constexpr.hpp>
+#include <boost/hana/ext/std/array.hpp>
+#include <boost/hana/ext/std/tuple.hpp>
+#include <boost/hana/foldable.hpp>
+#include <boost/hana/integral_constant.hpp>
+#include <boost/hana/logical.hpp>
+#include <boost/hana/range.hpp>
+#include <boost/hana/sequence.hpp>
+#include <boost/hana/tuple.hpp>
+
+#include <array>
+#include <tuple>
+using namespace boost::hana;
+
+
+int main() {
+
+{
+
+//! [tuple_t]
+BOOST_HANA_CONSTANT_CHECK(
+    to<Tuple>(tuple_t<int, char, void, int(float)>)
+    ==
+    tuple(type<int>, type<char>, type<void>, type<int(float)>)
+);
+//! [tuple_t]
+
+}{
+
+//! [tuple_c]
+BOOST_HANA_CONSTANT_CHECK(
+    to<Tuple>(tuple_c<int, 0, 1, 2>)
+    ==
+    tuple(int_<0>, int_<1>, int_<2>)
+);
+BOOST_HANA_CONSTANT_CHECK(head(tuple_c<int, 0, 1, 2>) == int_<0>);
+//! [tuple_c]
+
+}{
+
+//! [Foldable]
+using namespace literals;
+
+constexpr auto numbers = tuple_c<int, 5, -1, 0, -7, -2, 0, -5, 4>;
+constexpr auto negatives = tuple_c<int, -1, -7, -2, -5>;
+
+BOOST_HANA_CONSTEXPR_LAMBDA auto keep_negatives = [](auto n, auto acc) {
+    return if_(n < 0_c, prepend(n, acc), acc);
+};
+
+BOOST_HANA_CONSTANT_CHECK(foldr(numbers, tuple_c<int>, keep_negatives) == negatives);
+//! [Foldable]
+
+}{
+
+//! [Tuple_interop]
+BOOST_HANA_CONSTEXPR_CHECK(
+    to<Tuple>(std::make_tuple(1, '2', 3.3)) == tuple(1, '2', 3.3)
+);
+
+BOOST_HANA_CONSTANT_CHECK(
+    to<Tuple>(range(int_<1>, int_<4>)) == tuple(int_<1>, int_<2>, int_<3>)
+);
+
+BOOST_HANA_CONSTEXPR_CHECK(
+    to<Tuple>(std::array<int, 3>{{1, 2, 3}}) == tuple(1, 2, 3)
+);
+//! [Tuple_interop]
+
+}
+
+}