json/tests/src/unit-comparison.cpp

/*
    __ _____ _____ _____
 __|  |   __|     |   | |  JSON for Modern C++ (test suite)
|  |  |__   |  |  | | | |  version 3.10.5
|_____|_____|_____|_|___|  https://github.com/nlohmann/json

Licensed under the MIT License <http://opensource.org/licenses/MIT>.
SPDX-License-Identifier: MIT
Copyright (c) 2013-2022 Niels Lohmann <http://nlohmann.me>.

Permission is hereby  granted, free of charge, to any  person obtaining a copy
of this software and associated  documentation files (the "Software"), to deal
in the Software  without restriction, including without  limitation the rights
to  use, copy,  modify, merge,  publish, distribute,  sublicense, and/or  sell
copies  of  the Software,  and  to  permit persons  to  whom  the Software  is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE  IS PROVIDED "AS  IS", WITHOUT WARRANTY  OF ANY KIND,  EXPRESS OR
IMPLIED,  INCLUDING BUT  NOT  LIMITED TO  THE  WARRANTIES OF  MERCHANTABILITY,
FITNESS FOR  A PARTICULAR PURPOSE AND  NONINFRINGEMENT. IN NO EVENT  SHALL THE
AUTHORS  OR COPYRIGHT  HOLDERS  BE  LIABLE FOR  ANY  CLAIM,  DAMAGES OR  OTHER
LIABILITY, WHETHER IN AN ACTION OF  CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

// cmake/test.cmake selects the C++ standard versions with which to build a
// unit test based on the presence of JSON_HAS_CPP_<VERSION> macros.
// When using macros that are only defined for particular versions of the standard
// (e.g., JSON_HAS_FILESYSTEM for C++17 and up), please mention the corresponding
// version macro in a comment close by, like this:
// JSON_HAS_CPP_<VERSION> (do not remove; see note at top of file)

#include "doctest_compatibility.h"

#define JSON_TESTS_PRIVATE
#include <nlohmann/json.hpp>
using nlohmann::json;

#if JSON_HAS_THREE_WAY_COMPARISON
// this can be replaced with the doctest stl extension header in version 2.5
namespace doctest
{
template<> struct StringMaker<std::partial_ordering>
{
    static String convert(const std::partial_ordering& order)
    {
        if (order == std::partial_ordering::less)
        {
            return "std::partial_ordering::less";
        }
        if (order == std::partial_ordering::equivalent)
        {
            return "std::partial_ordering::equivalent";
        }
        if (order == std::partial_ordering::greater)
        {
            return "std::partial_ordering::greater";
        }
        if (order == std::partial_ordering::unordered)
        {
            return "std::partial_ordering::unordered";
        }
        return "{?}";
    }
};
} // namespace doctest
#endif

namespace
{
// helper function to check std::less<json::value_t>
// see https://en.cppreference.com/w/cpp/utility/functional/less
template <typename A, typename B, typename U = std::less<json::value_t>>
bool f(A a, B b, U u = U())
{
    return u(a, b);
}
} // namespace

TEST_CASE("lexicographical comparison operators")
{
    constexpr auto f_ = false;
    constexpr auto _t = true;
    constexpr auto nan = std::numeric_limits<json::number_float_t>::quiet_NaN();
#if JSON_HAS_THREE_WAY_COMPARISON
    constexpr auto lt = std::partial_ordering::less;
    constexpr auto gt = std::partial_ordering::greater;
    constexpr auto eq = std::partial_ordering::equivalent;
    constexpr auto un = std::partial_ordering::unordered;
#endif

#if JSON_HAS_THREE_WAY_COMPARISON
    INFO("using 3-way comparison");
#endif

#if JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
    INFO("using legacy comparison");
#endif

    //REQUIRE(std::numeric_limits<json::number_float_t>::has_quiet_NaN);
    REQUIRE(std::isnan(nan));

    SECTION("types")
    {
        std::vector<json::value_t> j_types =
        {
            json::value_t::null,
            json::value_t::boolean,
            json::value_t::number_integer,
            json::value_t::number_unsigned,
            json::value_t::number_float,
            json::value_t::object,
            json::value_t::array,
            json::value_t::string,
            json::value_t::binary,
            json::value_t::discarded
        };

        std::vector<std::vector<bool>> expected_lt =
        {
            //0   1   2   3   4   5   6   7   8   9
            {f_, _t, _t, _t, _t, _t, _t, _t, _t, f_}, //  0
            {f_, f_, _t, _t, _t, _t, _t, _t, _t, f_}, //  1
            {f_, f_, f_, f_, f_, _t, _t, _t, _t, f_}, //  2
            {f_, f_, f_, f_, f_, _t, _t, _t, _t, f_}, //  3
            {f_, f_, f_, f_, f_, _t, _t, _t, _t, f_}, //  4
            {f_, f_, f_, f_, f_, f_, _t, _t, _t, f_}, //  5
            {f_, f_, f_, f_, f_, f_, f_, _t, _t, f_}, //  6
            {f_, f_, f_, f_, f_, f_, f_, f_, _t, f_}, //  7
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  8
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  9
        };

        SECTION("comparison: less")
        {
            REQUIRE(expected_lt.size() == j_types.size());
            for (size_t i = 0; i < j_types.size(); ++i)
            {
                REQUIRE(expected_lt[i].size() == j_types.size());
                for (size_t j = 0; j < j_types.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    // check precomputed values
#if JSON_HAS_THREE_WAY_COMPARISON
                    // JSON_HAS_CPP_20 (do not remove; see note at top of file)
                    CHECK((j_types[i] < j_types[j]) == expected_lt[i][j]);
#else
                    CHECK(operator<(j_types[i], j_types[j]) == expected_lt[i][j]);
#endif
                    CHECK(f(j_types[i], j_types[j]) == expected_lt[i][j]);
                }
            }
        }
#if JSON_HAS_THREE_WAY_COMPARISON
        // JSON_HAS_CPP_20 (do not remove; see note at top of file)
        SECTION("comparison: 3-way")
        {
            std::vector<std::vector<std::partial_ordering>> expected =
            {
                //0   1   2   3   4   5   6   7   8   9
                {eq, lt, lt, lt, lt, lt, lt, lt, lt, un}, //  0
                {gt, eq, lt, lt, lt, lt, lt, lt, lt, un}, //  1
                {gt, gt, eq, eq, eq, lt, lt, lt, lt, un}, //  2
                {gt, gt, eq, eq, eq, lt, lt, lt, lt, un}, //  3
                {gt, gt, eq, eq, eq, lt, lt, lt, lt, un}, //  4
                {gt, gt, gt, gt, gt, eq, lt, lt, lt, un}, //  5
                {gt, gt, gt, gt, gt, gt, eq, lt, lt, un}, //  6
                {gt, gt, gt, gt, gt, gt, gt, eq, lt, un}, //  7
                {gt, gt, gt, gt, gt, gt, gt, gt, eq, un}, //  8
                {un, un, un, un, un, un, un, un, un, un}, //  9
            };

            // check expected partial_ordering against expected boolean
            REQUIRE(expected.size() == expected_lt.size());
            for (size_t i = 0; i < expected.size(); ++i)
            {
                REQUIRE(expected[i].size() == expected_lt[i].size());
                for (size_t j = 0; j < expected[i].size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    CHECK(std::is_lt(expected[i][j]) == expected_lt[i][j]);
                }
            }

            // check 3-way comparison against expected partial_ordering
            REQUIRE(expected.size() == j_types.size());
            for (size_t i = 0; i < j_types.size(); ++i)
            {
                REQUIRE(expected[i].size() == j_types.size());
                for (size_t j = 0; j < j_types.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    CHECK((j_types[i] <=> j_types[j]) == expected[i][j]); // *NOPAD*
                }
            }
        }
#endif
    }

    SECTION("values")
    {
        json j_values =
        {
            nullptr, nullptr,                                              // 0 1
            -17, 42,                                                       // 2 3
            8u, 13u,                                                       // 4 5
            3.14159, 23.42,                                                // 6 7
            nan, nan,                                                      // 8 9
            "foo", "bar",                                                  // 10 11
            true, false,                                                   // 12 13
            {1, 2, 3}, {"one", "two", "three"},                            // 14 15
            {{"first", 1}, {"second", 2}}, {{"a", "A"}, {"b", {"B"}}},     // 16 17
            json::binary({1, 2, 3}), json::binary({1, 2, 4}),              // 18 19
            json(json::value_t::discarded), json(json::value_t::discarded) // 20 21
        };

        std::vector<std::vector<bool>> expected_eq =
        {
            //0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21
            {_t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  0
            {_t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  1
            {f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  2
            {f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  3
            {f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  4
            {f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  5
            {f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  6
            {f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  7
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  8
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  9
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 10
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 11
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 12
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, f_}, // 13
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_}, // 14
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_}, // 15
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_}, // 16
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_}, // 17
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_}, // 18
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_}, // 19
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 20
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 21
        };

        std::vector<std::vector<bool>> expected_lt =
        {
            //0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21
            {f_, f_, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, f_, f_}, //  0
            {f_, f_, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, f_, f_}, //  1
            {f_, f_, f_, _t, _t, _t, _t, _t, f_, f_, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, //  2
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, //  3
            {f_, f_, f_, _t, f_, _t, f_, _t, f_, f_, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, //  4
            {f_, f_, f_, _t, f_, f_, f_, _t, f_, f_, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, //  5
            {f_, f_, f_, _t, _t, _t, f_, _t, f_, f_, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, //  6
            {f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, //  7
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, //  8
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, //  9
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_}, // 10
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_}, // 11
            {f_, f_, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, f_, f_, _t, _t, _t, _t, _t, _t, f_, f_}, // 12
            {f_, f_, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, f_, _t, _t, _t, _t, _t, _t, f_, f_}, // 13
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, _t, f_, f_, _t, _t, f_, f_}, // 14
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_}, // 15
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, _t, _t, f_, f_, _t, _t, f_, f_}, // 16
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, _t, _t, _t, f_, _t, _t, f_, f_}, // 17
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, f_, f_}, // 18
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 19
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 20
            {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 21
        };

        SECTION("compares unordered")
        {
            std::vector<std::vector<bool>> expected =
            {
                //0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  0
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  1
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  2
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  3
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  4
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  5
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  6
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  7
                {f_, f_, _t, _t, _t, _t, _t, _t, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  8
                {f_, f_, _t, _t, _t, _t, _t, _t, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, //  9
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 10
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 11
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 12
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 13
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 14
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 15
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 16
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 17
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 18
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, _t, _t}, // 19
                {_t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t}, // 20
                {_t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t, _t}, // 21
            };

            // check if two values compare unordered as expected
            REQUIRE(expected.size() == j_values.size());
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                REQUIRE(expected[i].size() == j_values.size());
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    CHECK(json::compares_unordered(j_values[i], j_values[j]) == expected[i][j]);
                }
            }
        }

#if JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
        SECTION("compares unordered (inverse)")
        {
            std::vector<std::vector<bool>> expected =
            {
                //0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  0
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  1
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  2
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  3
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  4
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  5
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  6
                {f_, f_, f_, f_, f_, f_, f_, f_, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  7
                {f_, f_, _t, _t, _t, _t, _t, _t, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  8
                {f_, f_, _t, _t, _t, _t, _t, _t, _t, _t, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, //  9
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 10
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 11
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 12
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 13
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 14
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 15
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 16
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 17
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 18
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 19
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 20
                {f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_, f_}, // 21
            };

            // check that two values compare unordered as expected (with legacy-mode enabled)
            REQUIRE(expected.size() == j_values.size());
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                REQUIRE(expected[i].size() == j_values.size());
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    CAPTURE(j_values[i])
                    CAPTURE(j_values[j])
                    CHECK(json::compares_unordered(j_values[i], j_values[j], true) == expected[i][j]);
                }
            }
        }
#endif

        SECTION("comparison: equal")
        {
            // check that two values compare equal
            REQUIRE(expected_eq.size() == j_values.size());
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                REQUIRE(expected_eq[i].size() == j_values.size());
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    CHECK((j_values[i] == j_values[j]) == expected_eq[i][j]);
                }
            }

            // compare with null pointer
            json j_null;
            CHECK(j_null == nullptr);
            CHECK(nullptr == j_null);
        }

        SECTION("comparison: not equal")
        {
            // check that two values compare unequal as expected
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)

                    if (json::compares_unordered(j_values[i], j_values[j], true))
                    {
                        // if two values compare unordered,
                        // check that the boolean comparison result is always false
                        CHECK_FALSE(j_values[i] != j_values[j]);
                    }
                    else
                    {
                        // otherwise, check that they compare according to their definition
                        // as the inverse of equal
                        CHECK((j_values[i] != j_values[j]) == !(j_values[i] == j_values[j]));
                    }
                }
            }

            // compare with null pointer
            json j_null;
            CHECK((j_null != nullptr) == false);
            CHECK((nullptr != j_null) == false);
            CHECK((j_null != nullptr) == !(j_null == nullptr));
            CHECK((nullptr != j_null) == !(nullptr == j_null));
        }

        SECTION("comparison: less")
        {
            // check that two values compare less than as expected
            REQUIRE(expected_lt.size() == j_values.size());
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                REQUIRE(expected_lt[i].size() == j_values.size());
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    CHECK((j_values[i] < j_values[j]) == expected_lt[i][j]);
                }
            }
        }

        SECTION("comparison: less than or equal equal")
        {
            // check that two values compare less than or equal as expected
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    if (json::compares_unordered(j_values[i], j_values[j], true))
                    {
                        // if two values compare unordered,
                        // check that the boolean comparison result is always false
                        CHECK_FALSE(j_values[i] <= j_values[j]);
                    }
                    else
                    {
                        // otherwise, check that they compare according to their definition
                        // as the inverse of less than with the operand order reversed
                        CHECK((j_values[i] <= j_values[j]) == !(j_values[j] < j_values[i]));
                    }
                }
            }
        }

        SECTION("comparison: greater than")
        {
            // check that two values compare greater than as expected
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    if (json::compares_unordered(j_values[i], j_values[j]))
                    {
                        // if two values compare unordered,
                        // check that the boolean comparison result is always false
                        CHECK_FALSE(j_values[i] > j_values[j]);
                    }
                    else
                    {
                        // otherwise, check that they compare according to their definition
                        // as the inverse of less than or equal which is defined as
                        // the inverse of less than with the operand order reversed
                        CHECK((j_values[i] > j_values[j]) == !(j_values[i] <= j_values[j]));
                        CHECK((j_values[i] > j_values[j]) == !!(j_values[j] < j_values[i]));
                    }
                }
            }
        }

        SECTION("comparison: greater than or equal")
        {
            // check that two values compare greater than or equal as expected
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    if (json::compares_unordered(j_values[i], j_values[j], true))
                    {
                        // if two values compare unordered,
                        // check that the boolean result is always false
                        CHECK_FALSE(j_values[i] >= j_values[j]);
                    }
                    else
                    {
                        // otherwise, check that they compare according to their definition
                        // as the inverse of less than
                        CHECK((j_values[i] >= j_values[j]) == !(j_values[i] < j_values[j]));
                    }
                }
            }
        }

#if JSON_HAS_THREE_WAY_COMPARISON
        // JSON_HAS_CPP_20 (do not remove; see note at top of file)
        SECTION("comparison: 3-way")
        {
            std::vector<std::vector<std::partial_ordering>> expected =
            {
                //0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21
                {eq, eq, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, un, un}, //  0
                {eq, eq, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, un, un}, //  1
                {gt, gt, eq, lt, lt, lt, lt, lt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, //  2
                {gt, gt, gt, eq, gt, gt, gt, gt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, //  3
                {gt, gt, gt, lt, eq, lt, gt, lt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, //  4
                {gt, gt, gt, lt, gt, eq, gt, lt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, //  5
                {gt, gt, gt, lt, lt, lt, eq, lt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, //  6
                {gt, gt, gt, lt, gt, gt, gt, eq, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, //  7
                {gt, gt, un, un, un, un, un, un, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, //  8
                {gt, gt, un, un, un, un, un, un, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, //  9
                {gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, eq, gt, gt, gt, gt, gt, gt, gt, lt, lt, un, un}, // 10
                {gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, eq, gt, gt, gt, gt, gt, gt, lt, lt, un, un}, // 11
                {gt, gt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, eq, gt, lt, lt, lt, lt, lt, lt, un, un}, // 12
                {gt, gt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, eq, lt, lt, lt, lt, lt, lt, un, un}, // 13
                {gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, lt, gt, gt, eq, lt, gt, gt, lt, lt, un, un}, // 14
                {gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, lt, gt, gt, gt, eq, gt, gt, lt, lt, un, un}, // 15
                {gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, lt, gt, gt, lt, lt, eq, gt, lt, lt, un, un}, // 16
                {gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, lt, gt, gt, lt, lt, lt, eq, lt, lt, un, un}, // 17
                {gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, eq, lt, un, un}, // 18
                {gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, eq, un, un}, // 19
                {un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un}, // 20
                {un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un}, // 21
            };

            // check expected partial_ordering against expected booleans
            REQUIRE(expected.size() == expected_eq.size());
            REQUIRE(expected.size() == expected_lt.size());
            for (size_t i = 0; i < expected.size(); ++i)
            {
                REQUIRE(expected[i].size() == expected_eq[i].size());
                REQUIRE(expected[i].size() == expected_lt[i].size());
                for (size_t j = 0; j < expected[i].size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    CHECK(std::is_eq(expected[i][j]) == expected_eq[i][j]);
                    CHECK(std::is_lt(expected[i][j]) == expected_lt[i][j]);
                    if (std::is_gt(expected[i][j]))
                    {
                        CHECK((!expected_eq[i][j] && !expected_lt[i][j]));
                    }
                }
            }

            // check that two values compare according to their expected ordering
            REQUIRE(expected.size() == j_values.size());
            for (size_t i = 0; i < j_values.size(); ++i)
            {
                REQUIRE(expected[i].size() == j_values.size());
                for (size_t j = 0; j < j_values.size(); ++j)
                {
                    CAPTURE(i)
                    CAPTURE(j)
                    CHECK((j_values[i] <=> j_values[j]) == expected[i][j]); // *NOPAD*
                }
            }
        }
#endif
    }

#if JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
    SECTION("parser callback regression")
    {
        SECTION("filter specific element")
        {
            const auto* s_object = R"(
                {
                    "foo": 2,
                    "bar": {
                        "baz": 1
                    }
                }
            )";
            const auto* s_array = R"(
                [1,2,[3,4,5],4,5]
            )";

            json j_object = json::parse(s_object, [](int /*unused*/, json::parse_event_t /*unused*/, const json & j) noexcept
            {
                // filter all number(2) elements
                return j != json(2);
            });

            CHECK (j_object == json({{"bar", {{"baz", 1}}}}));

            json j_array = json::parse(s_array, [](int /*unused*/, json::parse_event_t /*unused*/, const json & j) noexcept
            {
                return j != json(2);
            });

            CHECK (j_array == json({1, {3, 4, 5}, 4, 5}));
        }
    }
#endif
}