libs/hana/test/_include/auto/unfolds.hpp

   1 // Copyright Louis Dionne 2013-2017
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   4
   5 #ifndef BOOST_HANA_TEST_AUTO_UNFOLDS_HPP
   6 #define BOOST_HANA_TEST_AUTO_UNFOLDS_HPP
   7
   8 #include <boost/hana/assert.hpp>
   9 #include <boost/hana/equal.hpp>
  10 #include <boost/hana/fold_left.hpp>
  11 #include <boost/hana/fold_right.hpp>
  12 #include <boost/hana/if.hpp>
  13 #include <boost/hana/integral_constant.hpp>
  14 #include <boost/hana/optional.hpp>
  15 #include <boost/hana/plus.hpp>
  16 #include <boost/hana/unfold_left.hpp>
  17 #include <boost/hana/unfold_right.hpp>
  18
  19 #include <laws/base.hpp>
  20 #include <support/minimal_product.hpp>
  21 #include "test_case.hpp"
  22
  23
  24 TestCase test_unfold_left{[]{
  25     namespace hana = boost::hana;
  26
  27     hana::test::_injection<0> f{};
  28     auto stop_at = [=](auto stop) {
  29         return [=](auto x) {
  30             return hana::if_(hana::equal(stop, x),
  31                 hana::nothing,
  32                 hana::just(::minimal_product(x + hana::int_c<1>, f(x)))
  33             );
  34         };
  35     };
  36
  37     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  38         hana::unfold_left<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<0>)),
  39         MAKE_TUPLE()
  40     ));
  41     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  42         hana::unfold_left<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<1>)),
  43         MAKE_TUPLE(f(hana::int_c<0>))
  44     ));
  45     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  46         hana::unfold_left<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<2>)),
  47         MAKE_TUPLE(f(hana::int_c<1>), f(hana::int_c<0>))
  48     ));
  49     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  50         hana::unfold_left<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<3>)),
  51         MAKE_TUPLE(f(hana::int_c<2>), f(hana::int_c<1>), f(hana::int_c<0>))
  52     ));
  53     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  54         hana::unfold_left<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<4>)),
  55         MAKE_TUPLE(f(hana::int_c<3>), f(hana::int_c<2>), f(hana::int_c<1>), f(hana::int_c<0>))
  56     ));
  57 }};
  58
  59
  60 TestCase test_unfold_right{[]{
  61     namespace hana = boost::hana;
  62
  63     hana::test::_injection<0> f{};
  64     auto stop_at = [=](auto stop) {
  65         return [=](auto x) {
  66             return hana::if_(hana::equal(stop, x),
  67                 hana::nothing,
  68                 hana::just(::minimal_product(f(x), x + hana::int_c<1>))
  69             );
  70         };
  71     };
  72
  73     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  74         hana::unfold_right<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<0>)),
  75         MAKE_TUPLE()
  76     ));
  77     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  78         hana::unfold_right<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<1>)),
  79         MAKE_TUPLE(f(hana::int_c<0>))
  80     ));
  81     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  82         hana::unfold_right<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<2>)),
  83         MAKE_TUPLE(f(hana::int_c<0>), f(hana::int_c<1>))
  84     ));
  85     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  86         hana::unfold_right<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<3>)),
  87         MAKE_TUPLE(f(hana::int_c<0>), f(hana::int_c<1>), f(hana::int_c<2>))
  88     ));
  89     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  90         hana::unfold_right<TUPLE_TAG>(hana::int_c<0>, stop_at(hana::int_c<4>)),
  91         MAKE_TUPLE(f(hana::int_c<0>), f(hana::int_c<1>), f(hana::int_c<2>), f(hana::int_c<3>))
  92     ));
  93 }};
  94
  95 // Make sure unfolds can be reversed under certain conditions.
  96 TestCase test_unfold_undo{[]{
  97     namespace hana = boost::hana;
  98     using hana::test::ct_eq;
  99
 100     auto z = ct_eq<999>{};
 101     auto f = ::minimal_product;
 102     auto g = [=](auto k) {
 103         return hana::if_(hana::equal(k, z),
 104             hana::nothing,
 105             hana::just(k)
 106         );
 107     };
 108
 109     // Make sure the special conditions are met
 110     BOOST_HANA_CONSTANT_CHECK(hana::equal(
 111         g(z),
 112         hana::nothing
 113     ));
 114     BOOST_HANA_CONSTANT_CHECK(hana::equal(
 115         g(f(ct_eq<0>{}, z)),
 116         hana::just(::minimal_product(ct_eq<0>{}, z))
 117     ));
 118     BOOST_HANA_CONSTANT_CHECK(hana::equal(
 119         g(f(z, ct_eq<0>{})),
 120         hana::just(::minimal_product(z, ct_eq<0>{}))
 121     ));
 122
 123     // Make sure the reversing works
 124     {
 125         auto xs = MAKE_TUPLE();
 126         BOOST_HANA_CONSTANT_CHECK(hana::equal(
 127             hana::unfold_left<TUPLE_TAG>(hana::fold_left(xs, z, f), g),
 128             xs
 129         ));
 130         BOOST_HANA_CONSTANT_CHECK(hana::equal(
 131             hana::unfold_right<TUPLE_TAG>(hana::fold_right(xs, z, f), g),
 132             xs
 133         ));
 134     }
 135     {
 136         auto xs = MAKE_TUPLE(ct_eq<0>{});
 137         BOOST_HANA_CONSTANT_CHECK(hana::equal(
 138             hana::unfold_left<TUPLE_TAG>(hana::fold_left(xs, z, f), g),
 139             xs
 140         ));
 141         BOOST_HANA_CONSTANT_CHECK(hana::equal(
 142             hana::unfold_right<TUPLE_TAG>(hana::fold_right(xs, z, f), g),
 143             xs
 144         ));
 145     }
 146     {
 147         auto xs = MAKE_TUPLE(ct_eq<0>{}, ct_eq<1>{});
 148         BOOST_HANA_CONSTANT_CHECK(hana::equal(
 149             hana::unfold_left<TUPLE_TAG>(hana::fold_left(xs, z, f), g),
 150             xs
 151         ));
 152         BOOST_HANA_CONSTANT_CHECK(hana::equal(
 153             hana::unfold_right<TUPLE_TAG>(hana::fold_right(xs, z, f), g),
 154             xs
 155         ));
 156     }
 157     {
 158         auto xs = MAKE_TUPLE(ct_eq<0>{}, ct_eq<1>{}, ct_eq<2>{});
 159         BOOST_HANA_CONSTANT_CHECK(hana::equal(
 160             hana::unfold_left<TUPLE_TAG>(hana::fold_left(xs, z, f), g),
 161             xs
 162         ));
 163         BOOST_HANA_CONSTANT_CHECK(hana::equal(
 164             hana::unfold_right<TUPLE_TAG>(hana::fold_right(xs, z, f), g),
 165             xs
 166         ));
 167     }
 168 }};
 169
 170 #endif // !BOOST_HANA_TEST_AUTO_UNFOLDS_HPP