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json/tests/src/unit-json_view_dump.cpp
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2026-10-26 06:54:53 +01:00

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// __ _____ _____ _____
// __| | __| | | | 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
#include "doctest_compatibility.h"
#include <nlohmann/json_view.hpp>
using nlohmann::json;
using nlohmann::ordered_json;
using nlohmann::json_document;
using nlohmann::ordered_json_editable_document;
using nlohmann::json_view;
using nlohmann::ordered_json_document;
using nlohmann::ordered_json_view;
#include "json_view_test_helpers.hpp"
using json_view_test::generator;
using json_view_test::has_duplicate_keys;
#include <algorithm>
#include <array>
#include <cmath>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <iomanip>
#include <map>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <vector>
// These tests were split off unit-json_view.cpp, whose object file got too large for the MinGW
// linker (see json_view_test_helpers.hpp). Like that file, this one is also built
// with C++17, as it mentions JSON_HAS_CPP_17.
TEST_CASE("json_view dump")
{
SECTION("the output of ordered_json::dump()")
{
generator g;
for (int i = 0; i < 2000; ++i)
{
std::string text;
g.value(text, 0);
const ordered_json_document d = ordered_json_document::parse(text);
if (has_duplicate_keys(d.root()))
{
continue;
}
CAPTURE(text)
const ordered_json j = ordered_json::parse(text);
for (const int indent :
{
-1, 0, 2
})
{
for (const bool ensure_ascii :
{
false, true
})
{
CHECK(d.root().dump(indent, i % 2 == 0 ? ' ' : '\t', ensure_ascii) == j.dump(indent, i % 2 == 0 ? ' ' : '\t', ensure_ascii));
}
}
// also of each element
for (const ordered_json_view e : d.root())
{
CHECK(e.dump() == e.materialize().dump());
}
}
}
SECTION("strings")
{
const std::string text = R"(["plain", "\u0000\u0001\u001f\u007f\u0080é€￿😀", "\"\\\/\b\f\n\r\t", "aéあ😀b", "long text beyond the eight bytes of a word \n with an escape in the middle"])";
const ordered_json_document d = ordered_json_document::parse(text);
const ordered_json j = ordered_json::parse(text);
CHECK(d.root().dump() == j.dump());
CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
CHECK(d.root().dump(4, ' ', true) == j.dump(4, ' ', true));
const std::string key_text = R"({"é\n": {"\"": [], "": {}}})";
const ordered_json_document keys = ordered_json_document::parse(key_text);
const ordered_json key_json = ordered_json::parse(key_text);
CHECK(keys.root().dump(2, ' ', true) == key_json.dump(2, ' ', true));
}
SECTION("numbers")
{
const std::string text = "[1.50, 1E2, -0, -0.0, 123456789012345678901234567890, 18446744073709551615, -9223372036854775808, 0.1, 1e-7, 5e-324]";
const json_document d = json_document::parse(text);
CHECK(d.root().dump() == json::parse(text).dump());
CHECK(d.root().dump() == "[1.5,100.0,0,-0.0,1.2345678901234568e+29,18446744073709551615,-9223372036854775808,0.1,1e-07,5e-324]");
CHECK(d.root().dump(-1, ' ', false, json_view::number_format::source) == "[1.50,1E2,-0,-0.0,123456789012345678901234567890,18446744073709551615,-9223372036854775808,0.1,1e-7,5e-324]");
// also indented, and with ensure_ascii
CHECK(d.root().dump(0, ' ', false, json_view::number_format::source) == "[\n1.50,\n1E2,\n-0,\n-0.0,\n123456789012345678901234567890,\n18446744073709551615,\n-9223372036854775808,\n0.1,\n1e-7,\n5e-324\n]");
CHECK(d.root().dump(-1, ' ', true, json_view::number_format::source) == "[1.50,1E2,-0,-0.0,123456789012345678901234567890,18446744073709551615,-9223372036854775808,0.1,1e-7,5e-324]");
// float tokens of up to 17 significant digits in every spelling: those
// of at most 15 digits are written from their digits, the others
// through the conversion; both as dump() writes them
{
std::mt19937_64 tokens(1170); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
// a number below n; the remainder is a std::uint64_t, which is
// std::size_t on some platforms and wider on others
const auto draw = [&tokens](std::size_t n)
{
const std::uint64_t r = tokens() % n;
return static_cast<std::size_t>(r);
};
std::string many_tokens = "[";
for (int i = 0; i < 20000; ++i)
{
const std::size_t length = 1 + draw(17);
std::string digits(1, static_cast<char>('1' + draw(9)));
for (std::size_t k = 1; k < length; ++k)
{
digits += static_cast<char>('0' + draw(10));
}
digits += std::string(draw(4), '0'); // trailing zeros
std::string token = draw(3) == 0 ? "-" : "";
const std::size_t point = draw(digits.size() + 1);
if (point == 0)
{
token += "0." + std::string(draw(5), '0') + digits;
}
else
{
token += digits.substr(0, point) + (point < digits.size() ? "." + digits.substr(point) : "");
}
// an exponent that keeps the value between about 1e-320 and 1e300
const int exponent = static_cast<int>(draw(600)) - 300 - static_cast<int>(point);
if (draw(4) != 0)
{
token += (draw(2) == 0 ? "e" : "E") + std::string(exponent >= 0 && draw(2) == 0 ? "+" : "") + std::to_string(exponent);
}
else if (point == digits.size())
{
token += ".0"; // (a float, not an integer)
}
many_tokens += (i != 0 ? "," : "") + token;
}
many_tokens += ']';
const json_document many_doc = json_document::parse(many_tokens);
CHECK(many_doc.root().dump() == json::parse(many_tokens).dump());
}
// tokens of 16 and 17 digits without an exponent (like GeoJSON
// coordinates), which dump() converts in batches: doubles exactly
// halfway between two candidates for the shortest digits, random
// digits, and digits near a shorter decimal (...99999997,
// ...00000003), whose rounding carries; in pairs and among other
// values, so that the batches are interrupted; the last token near the
// end of the text
{
std::mt19937_64 tokens(5627); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
const auto draw = [&tokens](std::size_t n)
{
const std::uint64_t r = tokens() % n;
return static_cast<std::size_t>(r);
};
std::string coordinates = "[754570942.33984373,257769445.56835938,858106901.94921875,97944964.876953125,"
"[0.5,1e-7],[1.5,-0.0,2.5],[1E2,12.5,0.1,3.25,4.5,5.75,6.125,7.0,8.5],[],[1.5],[1,2.5],[2.5,\"x\"],[[1.5],2.5],";
for (int i = 0; i < 20000; ++i)
{
const std::size_t length = 16 + draw(2);
std::string digits(1, static_cast<char>('1' + draw(9)));
const std::size_t kept = draw(3) == 0 ? length : 2 + draw(length - 3);
for (std::size_t k = 1; k < kept; ++k)
{
digits += static_cast<char>('0' + draw(10));
}
digits += std::string(length - kept, draw(2) == 0 ? '9' : '0');
digits.back() = static_cast<char>('0' + draw(10));
const std::size_t point = 1 + draw(9);
const std::string token = (draw(2) == 0 ? "-" : "") + digits.substr(0, point) + "." + digits.substr(point);
if (i != 0)
{
coordinates += ',';
}
if (draw(8) == 0)
{
coordinates += R"({"x":)";
coordinates += token;
coordinates += R"(,"s":"a"})";
}
else
{
coordinates += '[';
coordinates += token;
coordinates += ',';
coordinates += token;
coordinates += ']';
}
}
coordinates += ",-65.613616999999977]";
const json_document parsed = json_document::parse(coordinates);
const ordered_json j = ordered_json::parse(coordinates);
CHECK(parsed.root().dump() == j.dump());
CHECK(parsed.root().dump(1) == j.dump(1));
CHECK(parsed.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
CHECK(parsed.root().back().get<double>() == j.back().get<double>());
CHECK(parsed.root().back().dump() == "-65.61361699999998");
std::size_t i = 0;
for (const json_view v : parsed.root())
{
const ordered_json& e = j[i++];
CHECK(v.dump() == e.dump());
if (v.is_array() && !v.empty() && v[0].is_number())
{
CHECK(v[0].get<double>() == e[0].get<double>());
}
}
// an editable document: edits move some arrays, so that the walk
// leaves the order of the parsed nodes
ordered_json_editable_document editable = ordered_json_editable_document::parse(coordinates);
ordered_json expected = j;
for (std::size_t k = 0; k < 20000; k += 97)
{
if (expected[k].is_array())
{
editable.push_back(editable.root()[k], ordered_json(1.5));
expected[k].push_back(1.5);
}
}
CHECK(editable.root().dump() == expected.dump());
}
// random doubles, written as parse() and dump() would
std::mt19937_64 rng(1170); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
std::string many = "[";
for (int i = 0; i < 5000; ++i)
{
const std::uint64_t bits = rng();
double x = 0;
std::memcpy(&x, &bits, sizeof(x));
if (std::isfinite(x))
{
many += (many.size() > 1 ? "," : "") + json(x).dump();
}
}
many += ']';
const json_document many_document = json_document::parse(many);
CHECK(many_document.root().dump() == json::parse(many).dump());
using json_float = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, float>;
const nlohmann::basic_json_document<json_float> float_document = nlohmann::basic_json_document<json_float>::parse("[0.1, 1.5e10, 3.4028235e38]");
CHECK(float_document.root().dump() == json_float::parse("[0.1, 1.5e10, 3.4028235e38]").dump());
}
}