Files
json/tests/src/unit-comparison.cpp
Niels Lohmann 6178982b8d Compare unordered objects by key below the nesting bound (#5582)
* Compare unordered objects by key below the nesting bound

Values nested deeper than the nesting bound are compared without the
call stack, walking both objects entry by entry. Two equal objects of a
type that enumerates its entries in no fixed order - std::unordered_map,
say - can be walked in different orders, so they compared unequal, and
a deep copy compared unequal to its original. std::unordered_map's own
operator== does not depend on the order, which is what applies above the
bound.

Where the keys differ, equality now finds the entry by its key instead.
An ordering, and ordered_map, whose operator== compares its entries in
sequence, still decide by the key.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Test unordered object equality without std::unordered_map

basic_json<std::unordered_map> instantiates std::pair<const string,
basic_json> while basic_json is still incomplete. The standard does not
require std::unordered_map to support that, and libstdc++ 6 to 9 as well
as the EDG front ends of icpc and nvc++ reject it, which broke the build
of unit-comparison on those CI jobs.

The test now uses an object type derived from std::map (which, as the
default object type, works everywhere) whose comparator orders keys
ascending or descending as chosen at construction, and whose operator==
does not depend on the order of the entries - the property of
std::unordered_map the test is about.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Compare the test object type's entries with std::all_of

clang-tidy (readability-use-anyofallof) asked for std::all_of instead of
the loop in unordered_object_t's operator==. The entry type is spelled
out, as C++11 needs typename for base_type::value_type and C++20
reports it as redundant.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-27 14:21:58 +02:00

955 lines
44 KiB
C++

// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++ (supporting code)
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
// 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"
#include <algorithm>
#include <cstdint>
#include <map>
#include <string>
#include <utility>
#include <vector>
#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("signed/unsigned mixed comparison above INT64_MAX")
{
const json above_int64_max = static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()) + 1ULL;
const json max_uint64 = (std::numeric_limits<std::uint64_t>::max)();
const json negative_one = -1;
const json one = 1;
const json max_int64 = (std::numeric_limits<std::int64_t>::max)();
CHECK_FALSE(above_int64_max == negative_one);
CHECK(above_int64_max != negative_one);
CHECK(negative_one < above_int64_max);
CHECK(negative_one <= above_int64_max);
CHECK_FALSE(negative_one > above_int64_max);
CHECK_FALSE(negative_one >= above_int64_max);
CHECK_FALSE(above_int64_max < negative_one);
CHECK_FALSE(above_int64_max <= negative_one);
CHECK(above_int64_max > negative_one);
CHECK(above_int64_max >= negative_one);
CHECK(negative_one != above_int64_max);
CHECK_FALSE(negative_one == above_int64_max);
CHECK_FALSE(max_uint64 == negative_one);
CHECK(max_uint64 != negative_one);
CHECK(negative_one < max_uint64);
CHECK(negative_one <= max_uint64);
CHECK_FALSE(negative_one > max_uint64);
CHECK_FALSE(negative_one >= max_uint64);
CHECK_FALSE(max_uint64 < negative_one);
CHECK_FALSE(max_uint64 <= negative_one);
CHECK(max_uint64 > negative_one);
CHECK(max_uint64 >= negative_one);
CHECK(negative_one != max_uint64);
CHECK_FALSE(negative_one == max_uint64);
CHECK_FALSE(one == above_int64_max);
CHECK(one != above_int64_max);
CHECK(one < above_int64_max);
CHECK(one <= above_int64_max);
CHECK_FALSE(one > above_int64_max);
CHECK_FALSE(one >= above_int64_max);
CHECK_FALSE(above_int64_max < one);
CHECK_FALSE(above_int64_max <= one);
CHECK(above_int64_max > one);
CHECK(above_int64_max >= one);
CHECK_FALSE(max_int64 == above_int64_max);
CHECK(max_int64 != above_int64_max);
CHECK(max_int64 < above_int64_max);
CHECK(max_int64 <= above_int64_max);
CHECK_FALSE(max_int64 > above_int64_max);
CHECK_FALSE(max_int64 >= above_int64_max);
CHECK_FALSE(above_int64_max < max_int64);
CHECK_FALSE(above_int64_max <= max_int64);
CHECK(above_int64_max > max_int64);
CHECK(above_int64_max >= max_int64);
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((negative_one <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
CHECK((above_int64_max <=> negative_one) == std::partial_ordering::greater); // *NOPAD*
CHECK((negative_one <=> max_uint64) == std::partial_ordering::less); // *NOPAD*
CHECK((max_uint64 <=> negative_one) == std::partial_ordering::greater); // *NOPAD*
CHECK((one <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
CHECK((above_int64_max <=> one) == std::partial_ordering::greater); // *NOPAD*
CHECK((max_int64 <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
CHECK((above_int64_max <=> max_int64) == std::partial_ordering::greater); // *NOPAD*
#endif
}
SECTION("integer/float mixed comparison is exact")
{
// Widening the integer to a double loses precision past the
// mantissa, so 2^63-2 and 2^63-1 both used to compare equal to the
// double 2^63 while differing from each other. That makes equality
// intransitive and the ordering not a strict weak ordering.
const json below_two_63 = static_cast<std::int64_t>(9223372036854775806LL);
const json max_int64 = (std::numeric_limits<std::int64_t>::max)();
const json two_63 = 9223372036854775808.0;
CHECK_FALSE(below_two_63 == two_63);
CHECK_FALSE(max_int64 == two_63);
CHECK(below_two_63 != max_int64);
CHECK(below_two_63 < max_int64);
CHECK(below_two_63 < two_63);
CHECK(max_int64 < two_63);
CHECK(two_63 > max_int64);
CHECK_FALSE(two_63 < max_int64);
// the same past the unsigned range
const json max_uint64 = (std::numeric_limits<std::uint64_t>::max)();
const json two_64 = 18446744073709551616.0;
CHECK_FALSE(max_uint64 == two_64);
CHECK(max_uint64 < two_64);
CHECK(two_64 > max_uint64);
// values a double represents exactly still compare equal
CHECK(json(1) == json(1.0));
CHECK(json(1u) == json(1.0));
CHECK(json(-3) == json(-3.0));
CHECK(json(1) < json(1.5));
CHECK(json(1.5) < json(2));
CHECK(json(2) > json(1.5));
CHECK(json(-1) > json(-1.5));
CHECK(json(-1.5) < json(-1));
CHECK(json(-2) < json(-1.5));
// a float below the range of the integer type
CHECK(json(0) > json(-1e30));
CHECK(json(-1e30) < json(0));
CHECK(json(0u) > json(-0.5));
CHECK(json(-0.5) < json(0u));
// a NaN operand stays unordered against either integer kind
CHECK_FALSE(json(1) == json(nan));
CHECK_FALSE(json(1) < json(nan));
CHECK_FALSE(json(nan) < json(1));
CHECK_FALSE(json(1u) == json(nan));
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((max_int64 <=> two_63) == std::partial_ordering::less); // *NOPAD*
CHECK((two_63 <=> max_int64) == std::partial_ordering::greater); // *NOPAD*
CHECK((below_two_63 <=> max_int64) == std::partial_ordering::less); // *NOPAD*
CHECK((max_uint64 <=> two_64) == std::partial_ordering::less); // *NOPAD*
CHECK((json(1) <=> json(1.0)) == std::partial_ordering::equivalent); // *NOPAD*
CHECK((json(1) <=> json(nan)) == std::partial_ordering::unordered); // *NOPAD*
#endif
}
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
// operator!= now means exactly !(a==b) without special cases for NaN/discarded
for (size_t i = 0; i < j_values.size(); ++i)
{
for (size_t j = 0; j < j_values.size(); ++j)
{
CAPTURE(i)
CAPTURE(j)
CHECK((j_values[i] != j_values[j]) == !(j_values[i] == j_values[j]));
}
}
// compare with null pointer
const json j_null;
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]
)";
const 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}}}}));
const 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
}
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
TEST_CASE("regression #3868 - heterogeneous comparisons compile under C++20 (P2468R2)")
{
// Issue #3868: operator!= was preventing compiler from synthesizing reversed
// operator== candidates under C++20's P2468R2 rewritten candidate rules.
// Verify that heterogeneous comparisons now work.
SECTION("string vs json")
{
std::string s = "string";
json j = "string";
CHECK(s == j);
CHECK(j == s);
CHECK_FALSE(s != j);
CHECK_FALSE(j != s);
}
SECTION("other heterogeneous types")
{
int i = 42;
json j = 42;
CHECK(i == j);
CHECK(j == i);
CHECK_FALSE(i != j);
CHECK_FALSE(j != i);
}
}
#endif
namespace
{
// orders keys ascending or descending, as chosen when a map is created
template<class Key>
class directed_less
{
public:
directed_less() = default;
explicit directed_less(const bool descending) noexcept
: m_descending(descending)
{}
bool operator()(const Key& lhs, const Key& rhs) const
{
return m_descending ? rhs < lhs : lhs < rhs;
}
private:
bool m_descending = false;
};
// An object type that, like std::unordered_map, enumerates its entries in no
// fixed order - ascending or descending by key, depending on how the map was
// created - and whose operator== does not depend on that order.
// std::unordered_map itself cannot be used here: the standard does not
// require it to accept an incomplete mapped type such as basic_json, and
// libstdc++ 6 to 9 as well as the EDG front ends of icpc and nvc++ reject
// basic_json<std::unordered_map>. std::map, the default object type, works
// with all supported compilers.
template<class Key, class Value, class /*Compare*/, class Allocator>
struct unordered_object_t : std::map<Key, Value, directed_less<Key>, Allocator>
{
using base_type = std::map<Key, Value, directed_less<Key>, Allocator>;
using base_type::base_type;
friend bool operator==(const unordered_object_t& lhs, const unordered_object_t& rhs)
{
return lhs.size() == rhs.size() && std::all_of(lhs.begin(), lhs.end(), [&rhs](const std::pair<const Key, Value>& entry)
{
const auto it = rhs.find(entry.first);
return it != rhs.end() && it->second == entry.second;
});
}
friend bool operator!=(const unordered_object_t& lhs, const unordered_object_t& rhs)
{
return !(lhs == rhs);
}
};
using unordered_json = nlohmann::basic_json<unordered_object_t>;
// the entries "0" to "9", enumerated in ascending or in descending order
unordered_json make_unordered_object(const bool descending)
{
unordered_json j = unordered_json::object_t(directed_less<std::string>(descending));
for (int i = 0; i < 10; ++i)
{
j[std::to_string(i)] = i;
}
return j;
}
template<typename Json>
Json nest(Json j, const std::size_t depth)
{
for (std::size_t i = 0; i < depth; ++i)
{
Json outer = Json::object();
outer["x"] = std::move(j);
j = std::move(outer);
}
return j;
}
} // namespace
TEST_CASE("equality of objects whose entries have no fixed order")
{
// Values nested deeper than a bound are compared without the call stack,
// entry by entry. That must agree with the object type's own operator==,
// which for unordered_object_t (as for std::unordered_map) does not
// depend on the order of the entries, and for ordered_map does.
REQUIRE(make_unordered_object(true).begin().key() == "9");
REQUIRE(make_unordered_object(false).begin().key() == "0");
for (const std::size_t depth : std::vector<std::size_t> {0, 200})
{
CAPTURE(depth);
const unordered_json descending = nest(make_unordered_object(true), depth);
const unordered_json ascending = nest(make_unordered_object(false), depth);
CHECK(descending == ascending);
CHECK_FALSE(descending != ascending);
// a copy is equal to its original
const unordered_json copy = descending; // NOLINT(performance-unnecessary-copy-initialization)
CHECK(copy == descending);
// a different value, a different key, or another entry still count
unordered_json other_value = make_unordered_object(true);
other_value["5"] = 42;
CHECK_FALSE(nest(other_value, depth) == ascending);
unordered_json other_key = make_unordered_object(true);
other_key.erase("5");
other_key["50"] = 5;
CHECK_FALSE(nest(other_key, depth) == ascending);
unordered_json more_entries = make_unordered_object(true);
more_entries["10"] = 10;
CHECK_FALSE(nest(more_entries, depth) == ascending);
CHECK_FALSE(ascending == nest(more_entries, depth));
// ordered_json compares its entries in sequence
const nlohmann::ordered_json ab = nest(nlohmann::ordered_json({{"a", 1}, {"b", 2}}), depth);
const nlohmann::ordered_json ba = nest(nlohmann::ordered_json({{"b", 2}, {"a", 1}}), depth);
CHECK_FALSE(ab == ba);
CHECK(ab != ba);
}
}
TEST_CASE("containers are compared element by element")
{
// Containers nested deeper than a bound are compared without the call
// stack, by code of their own; every relation is checked both at the top
// level and below that bound.
const auto deep = [](const json & j, const std::size_t depth)
{
json result = j;
for (std::size_t i = 0; i < depth; ++i)
{
result = json::array({std::move(result)});
}
return result;
};
for (const std::size_t depth : std::vector<std::size_t> {0, 200})
{
CAPTURE(depth);
// objects with different keys
{
const json a = deep({{"a", 1}}, depth);
const json b = deep({{"b", 1}}, depth);
CHECK_FALSE(a == b);
CHECK(a != b);
CHECK(a < b);
CHECK(b > a);
CHECK_FALSE(b < a);
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((a <=> b) == std::partial_ordering::less); // *NOPAD*
CHECK((b <=> a) == std::partial_ordering::greater); // *NOPAD*
CHECK((a <=> a) == std::partial_ordering::equivalent); // *NOPAD*
#endif
}
// a container that is a prefix of the other one
{
// the one that runs out of elements first is the smaller one
const json shorter = deep({1}, depth);
const json longer = deep({1, 2}, depth);
CHECK(shorter < longer);
CHECK(longer > shorter);
CHECK_FALSE(longer < shorter);
CHECK_FALSE(shorter == longer);
const json smaller_object = deep({{"a", 1}}, depth);
const json larger_object = deep({{"a", 1}, {"b", 2}}, depth);
CHECK(smaller_object < larger_object);
CHECK(larger_object > smaller_object);
CHECK_FALSE(smaller_object == larger_object);
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((shorter <=> longer) == std::partial_ordering::less); // *NOPAD*
CHECK((longer <=> shorter) == std::partial_ordering::greater); // *NOPAD*
#endif
}
// elements that cannot be ordered
{
const double nan = std::numeric_limits<double>::quiet_NaN();
const json lhs = deep({nan, 1}, depth);
const json rhs = deep({nan, 2}, depth);
CHECK_FALSE(lhs == lhs);
CHECK_FALSE(rhs < lhs);
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
// operator<=> stops there, as std::lexicographical_compare_three_way
// does, and operator< is derived from it
CHECK((lhs <=> rhs) == std::partial_ordering::unordered); // *NOPAD*
CHECK_FALSE(lhs < rhs);
#else
// operator< skips a pair of elements that cannot be ordered, as
// std::lexicographical_compare does, and the next pair decides
CHECK(lhs < rhs);
#endif
}
}
}