//     __ _____ _____ _____
//  __|  |   __|     |   | |  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"

// capture whether JSON_STRICT_NUL_HANDLING was enabled on the command line
// (e.g. -DJSON_STRICT_NUL_HANDLING=1) *before* including json.hpp, since the
// library #undefs JSON_STRICT_NUL_HANDLING itself once the header has been
// fully processed (see include/nlohmann/detail/macro_unscope.hpp)
#if defined(JSON_STRICT_NUL_HANDLING) && (JSON_STRICT_NUL_HANDLING == 1)
    #define JSON_TEST_STRICT_NUL_HANDLING_ENABLED 1
#endif

// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
// line *before* including json.hpp, since the library #undefs it once the header
// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
// tests of deprecated functions are skipped if these functions are deleted
#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
#endif

#include <nlohmann/json.hpp>
using nlohmann::json;
#ifdef JSON_TEST_NO_GLOBAL_UDLS
    using namespace nlohmann::literals; // NOLINT(google-build-using-namespace)
#endif

#include <iostream>
#include <iterator>
#include <list>
#include <sstream>
#include <string>
#include <valarray>
#include <vector>

#include "sax_event_loggers.hpp"

using utils::SaxEventLogger;
using utils::SaxEventLoggerExitAfterKey;
using utils::SaxEventLoggerExitAfterStartArray;
using utils::SaxEventLoggerExitAfterStartObject;

namespace
{
template <typename T>
class proxy_iterator
{
  public:
    using iterator = typename T::iterator;
    using value_type = typename std::iterator_traits<iterator>::value_type;
    using reference = typename std::iterator_traits<iterator>::reference;
    using pointer = typename std::iterator_traits<iterator>::pointer;
    using difference_type =
        typename std::iterator_traits<iterator>::difference_type;
    using iterator_category = std::input_iterator_tag;

    proxy_iterator() = default;
    explicit proxy_iterator(iterator& it) : m_it(std::addressof(it)) {}

    proxy_iterator& operator++()
    {
        ++*m_it;
        return *this;
    }

    proxy_iterator& operator--()
    {
        --*m_it;
        return *this;
    }

    bool operator==(const proxy_iterator& rhs) const
    {
        return (m_it && rhs.m_it) ? (*m_it == *rhs.m_it) : (m_it == rhs.m_it);
    }

    bool operator!=(const proxy_iterator& rhs) const
    {
        return !(*this == rhs);
    }

    reference operator*() const
    {
        return **m_it;
    }

  private:
    iterator* m_it = nullptr;
};

} // namespace

TEST_CASE("deserialization")
{
    SECTION("successful deserialization")
    {
        SECTION("stream")
        {
            std::stringstream ss1;
            std::stringstream ss2;
            std::stringstream ss3;
            ss1 << R"(["foo",1,2,3,false,{"one":1}])";
            ss2 << R"(["foo",1,2,3,false,{"one":1}])";
            ss3 << R"(["foo",1,2,3,false,{"one":1}])";
            const json j = json::parse(ss1);
            CHECK(json::accept(ss2));
            CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));

            SaxEventLogger l;
            CHECK(json::sax_parse(ss3, &l));
            CHECK(l.events.size() == 11);
            CHECK(l.events == std::vector<std::string>(
            {
                "start_array()", "string(foo)", "number_unsigned(1)",
                "number_unsigned(2)", "number_unsigned(3)", "boolean(false)",
                "start_object()", "key(one)", "number_unsigned(1)",
                "end_object()", "end_array()"
            }));
        }

        SECTION("string literal")
        {
            const auto* s = R"(["foo",1,2,3,false,{"one":1}])";
            const json j = json::parse(s);
            CHECK(json::accept(s));
            CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));

            SaxEventLogger l;
            CHECK(json::sax_parse(s, &l));
            CHECK(l.events.size() == 11);
            CHECK(l.events == std::vector<std::string>(
            {
                "start_array()", "string(foo)", "number_unsigned(1)",
                "number_unsigned(2)", "number_unsigned(3)", "boolean(false)",
                "start_object()", "key(one)", "number_unsigned(1)",
                "end_object()", "end_array()"
            }));
        }

        SECTION("string_t")
        {
            json::string_t const s = R"(["foo",1,2,3,false,{"one":1}])";
            const json j = json::parse(s);
            CHECK(json::accept(s));
            CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));

            SaxEventLogger l;
            CHECK(json::sax_parse(s, &l));
            CHECK(l.events.size() == 11);
            CHECK(l.events == std::vector<std::string>(
            {
                "start_array()", "string(foo)", "number_unsigned(1)",
                "number_unsigned(2)", "number_unsigned(3)", "boolean(false)",
                "start_object()", "key(one)", "number_unsigned(1)",
                "end_object()", "end_array()"
            }));
        }

#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
        SECTION("operator<<")
        {
            std::stringstream ss;
            ss << R"(["foo",1,2,3,false,{"one":1}])";
            json j;
            j << ss;
            CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));
        }
#endif

        SECTION("operator>>")
        {
            std::stringstream ss;
            ss << R"(["foo",1,2,3,false,{"one":1}])";
            json j;
            ss >> j;
            CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));
        }

        SECTION("operator>> with a NUL byte after the value (issue #5530)")
        {
            // operator>> parses non-strictly (it does not require the whole
            // stream to be consumed), so a NUL byte following a complete
            // value is simply left unread on the stream and never reaches
            // the "expected end of input" check that JSON_STRICT_NUL_HANDLING
            // affects; this holds regardless of the macro (verified below for
            // the opt-in state as well)
            std::string data = "123";
            data.push_back('\0');
            std::istringstream ss(data);
            json j;
            ss >> j;
            CHECK(j == json(123));
            CHECK(ss.good());
        }

        SECTION("user-defined string literal")
        {
            CHECK("[\"foo\",1,2,3,false,{\"one\":1}]"_json == json({"foo", 1, 2, 3, false, {{"one", 1}}}));
        }
    }

    SECTION("unsuccessful deserialization")
    {
        SECTION("stream")
        {
            std::stringstream ss1;
            std::stringstream ss3;
            std::stringstream ss4;
            std::stringstream ss5;
            ss1 << R"(["foo",1,2,3,false,{"one":1})";
            ss3 << R"(["foo",1,2,3,false,{"one":1})";
            ss4 << R"(["foo",1,2,3,false,{"one":1})";
            ss5 << R"(["foo",1,2,3,false,{"one":1})";

            json _;
            CHECK_THROWS_WITH_AS(_ = json::parse(ss1), "[json.exception.parse_error.101] parse error at line 1, column 29: syntax error while parsing array - unexpected end of input; expected ']'", json::parse_error&);
            CHECK(!json::accept(ss3));

            json j_error;
            CHECK_NOTHROW(j_error = json::parse(ss4, nullptr, false));
            CHECK(j_error.is_discarded());

            SaxEventLogger l;
            CHECK(!json::sax_parse(ss5, &l));
            CHECK(l.events.size() == 11);
            CHECK(l.events == std::vector<std::string>(
            {
                "start_array()", "string(foo)", "number_unsigned(1)",
                "number_unsigned(2)", "number_unsigned(3)", "boolean(false)",
                "start_object()", "key(one)", "number_unsigned(1)",
                "end_object()", "parse_error(29)"
            }));
        }

        SECTION("stream with eofbit in its exception mask (issue #5646)")
        {
            // reaching EOF while parsing a value that fills the whole input
            // (e.g., a number, or any value under strict parsing) makes
            // get_character() call std::istream::clear() to record eofbit;
            // with eofbit in the exception mask, that clear() itself throws
            // std::ios_base::failure - it must propagate to the caller instead
            // of ~input_stream_adapter() throwing a second exception while the
            // first is still unwinding, which would call std::terminate
            json _;

            std::istringstream is1("1");
            is1.exceptions(std::ios::eofbit);
            CHECK_THROWS_AS(_ = json::parse(is1), std::ios_base::failure&);

            // the same holds for the common std::ifstream::exceptions(failbit |
            // badbit | eofbit) pattern, because only eofbit ends up set
            std::istringstream is2("1");
            is2.exceptions(std::ios::failbit | std::ios::badbit | std::ios::eofbit);
            CHECK_THROWS_AS(_ = json::parse(is2), std::ios_base::failure&);
        }

        SECTION("stream without a streambuf (issue #5646)")
        {
            // std::istream(nullptr) has badbit set and rdbuf() == nullptr;
            // get_character() must not dereference that null streambuf
            std::istream is(nullptr);
            json _;
            CHECK_THROWS_WITH_AS(_ = json::parse(is), "[json.exception.parse_error.101] parse error: attempting to parse an empty input; check that your input string or stream contains the expected JSON", json::parse_error&);
        }

        SECTION("string")
        {
            json::string_t const s = R"(["foo",1,2,3,false,{"one":1})";
            json _;
            CHECK_THROWS_WITH_AS(_ = json::parse(s), "[json.exception.parse_error.101] parse error at line 1, column 29: syntax error while parsing array - unexpected end of input; expected ']'", json::parse_error&);
            CHECK(!json::accept(s));

            json j_error;
            CHECK_NOTHROW(j_error = json::parse(s, nullptr, false));
            CHECK(j_error.is_discarded());

            SaxEventLogger l;
            CHECK(!json::sax_parse(s, &l));
            CHECK(l.events.size() == 11);
            CHECK(l.events == std::vector<std::string>(
            {
                "start_array()", "string(foo)", "number_unsigned(1)",
                "number_unsigned(2)", "number_unsigned(3)", "boolean(false)",
                "start_object()", "key(one)", "number_unsigned(1)",
                "end_object()", "parse_error(29)"
            }));

            const char* string = nullptr;
            CHECK_THROWS_WITH_AS(_ = json::parse(string), "[json.exception.parse_error.101] parse error: attempting to parse an empty input; check that your input string or stream contains the expected JSON", json::parse_error&);
            CHECK_THROWS_WITH_AS(_ = json::parse(nullptr), "[json.exception.parse_error.101] parse error: attempting to parse an empty input; check that your input string or stream contains the expected JSON", json::parse_error&);
        }

#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
        SECTION("operator<<")
        {
            std::stringstream ss;
            ss << R"(["foo",1,2,3,false,{"one":1})";
            json j;
            CHECK_THROWS_WITH_AS(j << ss, "[json.exception.parse_error.101] parse error at line 1, column 29: syntax error while parsing array - unexpected end of input; expected ']'", json::parse_error&);
        }
#endif

        SECTION("operator>>")
        {
            std::stringstream ss;
            ss << R"(["foo",1,2,3,false,{"one":1})";
            json j;
            CHECK_THROWS_WITH_AS(ss >> j, "[json.exception.parse_error.101] parse error at line 1, column 29: syntax error while parsing array - unexpected end of input; expected ']'", json::parse_error&);
        }

#if defined(JSON_TEST_STRICT_NUL_HANDLING_ENABLED)
        SECTION("operator>> with a NUL byte where a value is expected (JSON_STRICT_NUL_HANDLING == 1, issue #5530)")
        {
            // a trailing NUL byte *after* a complete value is unaffected by the
            // macro (see the successful-deserialization "operator>> with a NUL
            // byte after the value" section above): operator>> parses
            // non-strictly and never reaches the "expected end of input" check
            // that the macro changes. A NUL byte where a *value* is expected,
            // however, goes through the same token dispatch as any other input
            // and is affected: with the macro enabled it now raises
            // parse_error.101 (like any other unrecognized byte) instead of
            // being silently treated the same as an empty stream.
            std::string const data(1, '\0');
            std::istringstream ss(data);
            json j;
            CHECK_THROWS_WITH_AS(ss >> j,
                                 "[json.exception.parse_error.101] parse error at line 1, column 1: syntax error while parsing value - invalid literal; last read: '<U+0000>'",
                                 json::parse_error&);
        }
#endif

        SECTION("user-defined string literal")
        {
            CHECK_THROWS_WITH_AS("[\"foo\",1,2,3,false,{\"one\":1}"_json, "[json.exception.parse_error.101] parse error at line 1, column 29: syntax error while parsing array - unexpected end of input; expected ']'", json::parse_error&);
        }
    }

    SECTION("contiguous containers")
    {
        SECTION("directly")
        {
            SECTION("from std::vector")
            {
                std::vector<uint8_t> const v = {'t', 'r', 'u', 'e'};
                CHECK(json::parse(v) == json(true));
                CHECK(json::accept(v));

                SaxEventLogger l;
                CHECK(json::sax_parse(v, &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("from std::vector<signed char>")
            {
                std::vector<signed char> const v = {'t', 'r', 'u', 'e'};
                CHECK(json::parse(v) == json(true));
                CHECK(json::accept(v));

                SaxEventLogger l;
                CHECK(json::sax_parse(v, &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));

                // bytes outside ASCII are negative here and must not be sign-extended;
                // 0xC3 and 0xA9 do not fit in signed char (MSVC C4309), so spell them as negative values
                std::vector<signed char> const umlaut = {'"', static_cast<signed char>(0xC3 - 0x100), static_cast<signed char>(0xA9 - 0x100), '"'};
                CHECK(json::parse(umlaut) == json("\xC3\xA9"));
                CHECK(json::accept(umlaut));

                // 0xFF (spelled as -1 to stay in range) must not be reported as end of input
                std::vector<signed char> const trailing = {'t', 'r', 'u', 'e', static_cast<signed char>(0xFF - 0x100)};
                json _;
                CHECK_THROWS_WITH_AS(_ = json::parse(trailing), "[json.exception.parse_error.101] parse error at line 1, column 5: syntax error while parsing value - invalid literal; last read: 'true\xFF'; expected end of input", json::parse_error&);
                CHECK(!json::accept(trailing));
            }

            SECTION("from std::array")
            {
                // sized to exactly the length of "true": a size of 5 would leave
                // a value-initialized trailing 0x00 element that is only
                // silently accepted as end-of-input by default and would fail
                // under JSON_STRICT_NUL_HANDLING
                std::array<uint8_t, 4> const v { {'t', 'r', 'u', 'e'} };
                CHECK(json::parse(v) == json(true));
                CHECK(json::accept(v));

                SaxEventLogger l;
                CHECK(json::sax_parse(v, &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("from array")
            {
                uint8_t v[] = {'t', 'r', 'u', 'e'}; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
                CHECK(json::parse(v) == json(true));
                CHECK(json::accept(v));

                SaxEventLogger l;
                CHECK(json::sax_parse(v, &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("from chars")
            {
                auto* v = new uint8_t[5]; // NOLINT(cppcoreguidelines-owning-memory)
                v[0] = 't';
                v[1] = 'r';
                v[2] = 'u';
                v[3] = 'e';
                v[4] = '\0';
                CHECK(json::parse(v) == json(true));
                CHECK(json::accept(v));

                SaxEventLogger l;
                CHECK(json::sax_parse(v, &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));

                delete[] v; // NOLINT(cppcoreguidelines-owning-memory)
            }

            SECTION("from std::string")
            {
                std::string const v = {'t', 'r', 'u', 'e'};
                CHECK(json::parse(v) == json(true));
                CHECK(json::accept(v));

                SaxEventLogger l;
                CHECK(json::sax_parse(v, &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("from std::initializer_list")
            {
                std::initializer_list<uint8_t> const v = {'t', 'r', 'u', 'e'};
                CHECK(json::parse(v) == json(true));
                CHECK(json::accept(v));

                SaxEventLogger l;
                CHECK(json::sax_parse(v, &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("empty container")
            {
                std::vector<uint8_t> const v;
                json _;
                CHECK_THROWS_AS(_ = json::parse(v), json::parse_error&);
                CHECK(!json::accept(v));

                SaxEventLogger l;
                CHECK(!json::sax_parse(v, &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(1)"}));
            }
        }

        SECTION("via iterator range")
        {
            SECTION("from std::vector")
            {
                std::vector<uint8_t> v = {'t', 'r', 'u', 'e'};
                CHECK(json::parse(std::begin(v), std::end(v)) == json(true));
                CHECK(json::accept(std::begin(v), std::end(v)));

                SaxEventLogger l;
                CHECK(json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));

            }

            SECTION("from std::array")
            {
                // sized to exactly the length of "true", see the analogous
                // "from std::array" section above for why
                std::array<uint8_t, 4> v { {'t', 'r', 'u', 'e'} };
                CHECK(json::parse(std::begin(v), std::end(v)) == json(true));
                CHECK(json::accept(std::begin(v), std::end(v)));

                SaxEventLogger l;
                CHECK(json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("from array")
            {
                uint8_t v[] = {'t', 'r', 'u', 'e'}; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
                CHECK(json::parse(std::begin(v), std::end(v)) == json(true));
                CHECK(json::accept(std::begin(v), std::end(v)));

                SaxEventLogger l;
                CHECK(json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("from std::string")
            {
                std::string v = {'t', 'r', 'u', 'e'};
                CHECK(json::parse(std::begin(v), std::end(v)) == json(true));
                CHECK(json::accept(std::begin(v), std::end(v)));

                SaxEventLogger l;
                CHECK(json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("from std::initializer_list")
            {
                std::initializer_list<uint8_t> const v = {'t', 'r', 'u', 'e'};
                CHECK(json::parse(std::begin(v), std::end(v)) == json(true));
                CHECK(json::accept(std::begin(v), std::end(v)));

                SaxEventLogger l;
                CHECK(json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("from std::valarray")
            {
                std::valarray<uint8_t> v = {'t', 'r', 'u', 'e'};
                CHECK(json::parse(std::begin(v), std::end(v)) == json(true));
                CHECK(json::accept(std::begin(v), std::end(v)));

                SaxEventLogger l;
                CHECK(json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
            }

            SECTION("with empty range")
            {
                std::vector<uint8_t> v;
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(1)"}));
            }

            SECTION("iterator_input_adapter advances iterators correctly")
            {
                using nlohmann::json;
                using nlohmann::detail::input_format_t;
                using nlohmann::detail::json_sax_dom_parser;
                using proxy = proxy_iterator<std::string>;

                std::string str1 = "[1]";
                std::string str2 = "[2]";
                std::string str = str1 + str2;

                auto first = str.begin();
                auto last = str.end();
                json j;
                json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type> sax(j, true);

                CHECK(json::sax_parse(proxy(first), proxy(last), &sax,
                                      input_format_t::json, false));
                CHECK(j.dump() == str1);
                CHECK(std::string(first, last) == str2);
            }
        }

        // these cases are required for 100% line coverage
        SECTION("error cases")
        {
            SECTION("case 1")
            {
                std::array<std::uint8_t, 9> v = {{'\"', 'a', 'a', 'a', 'a', 'a', 'a', '\\', 'u'}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(10)"}));
            }

            SECTION("case 2")
            {
                std::array<std::uint8_t, 10> v = {{'\"', 'a', 'a', 'a', 'a', 'a', 'a', '\\', 'u', '1'}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(11)"}));
            }

            SECTION("case 3")
            {
                std::array<std::uint8_t, 17> v = {{'\"', 'a', 'a', 'a', 'a', 'a', 'a', '\\', 'u', '1', '1', '1', '1', '1', '1', '1', '1'}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(18)"}));
            }

            SECTION("case 4")
            {
                std::array<std::uint8_t, 17> v = {{'\"', 'a', 'a', 'a', 'a', 'a', 'a', 'u', '1', '1', '1', '1', '1', '1', '1', '1', '\\'}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(18)"}));
            }

            SECTION("case 5")
            {
                std::array<std::uint8_t, 3> v = {{'\"', 0x7F, 0xC1}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(3)"}));
            }

            SECTION("case 6")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xDF, 0x7F}};
                json _;
                CHECK_THROWS_WITH_AS(_ = json::parse(std::begin(v), std::end(v)), "[json.exception.parse_error.101] parse error at line 1, column 4: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '\"\x7f\xdf\x7f'", json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 7")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xDF, 0xC0}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 8")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xE0, 0x9F}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 9")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xEF, 0xC0}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 10")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xED, 0x7F}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 11")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xF0, 0x8F}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 12")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xF0, 0xC0}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 13")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xF3, 0x7F}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 14")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xF3, 0xC0}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 15")
            {
                std::array<std::uint8_t, 4> v = {{'\"', 0x7F, 0xF4, 0x7F}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 1);
                CHECK(l.events == std::vector<std::string>({"parse_error(4)"}));
            }

            SECTION("case 16")
            {
                std::array<std::uint8_t, 6> v = {{'{', '\"', '\"', ':', '1', '1'}};
                json _;
                CHECK_THROWS_AS(_ = json::parse(std::begin(v), std::end(v)), json::parse_error&);
                CHECK(!json::accept(std::begin(v), std::end(v)));

                json j_error;
                CHECK_NOTHROW(j_error = json::parse(std::begin(v), std::end(v), nullptr, false));
                CHECK(j_error.is_discarded());

                SaxEventLogger l;
                CHECK(!json::sax_parse(std::begin(v), std::end(v), &l));
                CHECK(l.events.size() == 4);
                CHECK(l.events == std::vector<std::string>(
                {
                    "start_object()", "key()", "number_unsigned(11)",
                    "parse_error(7)"
                }));
            }
        }
    }

    SECTION("ignoring byte-order marks")
    {
        std::string bom = "\xEF\xBB\xBF";

        SECTION("BOM only")
        {
            json _;
            CHECK_THROWS_WITH_AS(_ = json::parse(bom), "[json.exception.parse_error.101] parse error at line 1, column 4: syntax error while parsing value - unexpected end of input; expected '[', '{', or a literal", json::parse_error&);

            CHECK_THROWS_WITH_AS(_ = json::parse(std::istringstream(bom)), "[json.exception.parse_error.101] parse error at line 1, column 4: syntax error while parsing value - unexpected end of input; expected '[', '{', or a literal", json::parse_error&);

            SaxEventLogger l;
            CHECK(!json::sax_parse(bom, &l));
            CHECK(l.events.size() == 1);
            CHECK(l.events == std::vector<std::string>(
            {
                "parse_error(4)"
            }));
        }

        SECTION("BOM and content")
        {
            CHECK(json::parse(bom + "1") == 1);
            CHECK(json::parse(std::istringstream(bom + "1")) == 1);

            SaxEventLogger l1;
            SaxEventLogger l2;
            CHECK(json::sax_parse(std::istringstream(bom + "1"), &l1));
            CHECK(json::sax_parse(bom + "1", &l2));
            CHECK(l1.events.size() == 1);
            CHECK(l1.events == std::vector<std::string>(
            {
                "number_unsigned(1)"
            }));
            CHECK(l2.events.size() == 1);
            CHECK(l2.events == std::vector<std::string>(
            {
                "number_unsigned(1)"
            }));
        }

        SECTION("2 byte of BOM")
        {
            json _;
            CHECK_THROWS_WITH_AS(_ = json::parse(bom.substr(0, 2)), "[json.exception.parse_error.101] parse error at line 1, column 3: syntax error while parsing value - invalid BOM; must be 0xEF 0xBB 0xBF if given; last read: '\xEF\xBB'", json::parse_error&);

            CHECK_THROWS_WITH_AS(_ = json::parse(std::istringstream(bom.substr(0, 2))), "[json.exception.parse_error.101] parse error at line 1, column 3: syntax error while parsing value - invalid BOM; must be 0xEF 0xBB 0xBF if given; last read: '\xEF\xBB'", json::parse_error&);

            SaxEventLogger l1;
            SaxEventLogger l2;
            CHECK(!json::sax_parse(std::istringstream(bom.substr(0, 2)), &l1));
            CHECK(!json::sax_parse(bom.substr(0, 2), &l2));
            CHECK(l1.events.size() == 1);
            CHECK(l1.events == std::vector<std::string>(
            {
                "parse_error(3)"
            }));
            CHECK(l2.events.size() == 1);
            CHECK(l2.events == std::vector<std::string>(
            {
                "parse_error(3)"
            }));
        }

        SECTION("1 byte of BOM")
        {
            json _;
            CHECK_THROWS_WITH_AS(_ = json::parse(bom.substr(0, 1)), "[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid BOM; must be 0xEF 0xBB 0xBF if given; last read: '\xEF'", json::parse_error&);

            CHECK_THROWS_WITH_AS(_ = json::parse(std::istringstream(bom.substr(0, 1))), "[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid BOM; must be 0xEF 0xBB 0xBF if given; last read: '\xEF'", json::parse_error&);

            SaxEventLogger l1;
            SaxEventLogger l2;
            CHECK(!json::sax_parse(std::istringstream(bom.substr(0, 1)), &l1));
            CHECK(!json::sax_parse(bom.substr(0, 1), &l2));
            CHECK(l1.events.size() == 1);
            CHECK(l1.events == std::vector<std::string>(
            {
                "parse_error(2)"
            }));
            CHECK(l2.events.size() == 1);
            CHECK(l2.events == std::vector<std::string>(
            {
                "parse_error(2)"
            }));
        }

        SECTION("variations")
        {
            // calculate variations of each byte of the BOM to make sure
            // that the BOM and only the BOM is skipped
            for (int i0 = -1; i0 < 2; ++i0)
            {
                for (int i1 = -1; i1 < 2; ++i1)
                {
                    for (int i2 = -1; i2 < 2; ++i2)
                    {
                        // debug output for the variations
                        CAPTURE(i0)
                        CAPTURE(i1)
                        CAPTURE(i2)

                        std::string s;
                        s.push_back(static_cast<char>(bom[0] + i0));
                        s.push_back(static_cast<char>(bom[1] + i1));
                        s.push_back(static_cast<char>(bom[2] + i2));

                        if (i0 == 0 && i1 == 0 && i2 == 0)
                        {
                            // without any variation, we skip the BOM
                            CHECK(json::parse(s + "null") == json());
                            CHECK(json::parse(std::istringstream(s + "null")) == json());

                            SaxEventLogger l;
                            CHECK(json::sax_parse(s + "null", &l));
                            CHECK(l.events.size() == 1);
                            CHECK(l.events == std::vector<std::string>(
                            {
                                "null()"
                            }));
                        }
                        else
                        {
                            // any variation is an error
                            json _;
                            CHECK_THROWS_AS(_ = json::parse(s + "null"), json::parse_error&);
                            CHECK_THROWS_AS(_ = json::parse(std::istringstream(s + "null")), json::parse_error&);

                            SaxEventLogger l;
                            CHECK(!json::sax_parse(s + "null", &l));
                            CHECK(l.events.size() == 1);

                            if (i0 != 0)
                            {
                                CHECK(l.events == std::vector<std::string>(
                                {
                                    "parse_error(1)"
                                }));
                            }
                            else if (i1 != 0)
                            {
                                CHECK(l.events == std::vector<std::string>(
                                {
                                    "parse_error(2)"
                                }));
                            }
                            else
                            {
                                CHECK(l.events == std::vector<std::string>(
                                {
                                    "parse_error(3)"
                                }));
                            }
                        }
                    }
                }
            }
        }

        SECTION("preserve state after parsing")
        {
            std::istringstream s(bom + "123 456");
            json j;
            s >> j;
            CHECK(j == 123);
            s >> j;
            CHECK(j == 456);
        }
    }

    SECTION("SAX and early abort")
    {
        std::string const s = R"([1, ["string", 43.12], null, {"key1": true, "key2": false}])";

        SaxEventLogger default_logger;
        SaxEventLoggerExitAfterStartObject exit_after_start_object;
        SaxEventLoggerExitAfterKey exit_after_key;
        SaxEventLoggerExitAfterStartArray exit_after_start_array;

        json::sax_parse(s, &default_logger);
        CHECK(default_logger.events.size() == 14);
        CHECK(default_logger.events == std::vector<std::string>(
        {
            "start_array()", "number_unsigned(1)", "start_array()",
            "string(string)", "number_float(43.12)", "end_array()", "null()",
            "start_object()", "key(key1)", "boolean(true)", "key(key2)",
            "boolean(false)", "end_object()", "end_array()"
        }));

        json::sax_parse(s, &exit_after_start_object);
        CHECK(exit_after_start_object.events.size() == 8);
        CHECK(exit_after_start_object.events == std::vector<std::string>(
        {
            "start_array()", "number_unsigned(1)", "start_array()",
            "string(string)", "number_float(43.12)", "end_array()", "null()",
            "start_object()"
        }));

        json::sax_parse(s, &exit_after_key);
        CHECK(exit_after_key.events.size() == 9);
        CHECK(exit_after_key.events == std::vector<std::string>(
        {
            "start_array()", "number_unsigned(1)", "start_array()",
            "string(string)", "number_float(43.12)", "end_array()", "null()",
            "start_object()", "key(key1)"
        }));

        json::sax_parse(s, &exit_after_start_array);
        CHECK(exit_after_start_array.events.size() == 1);
        CHECK(exit_after_start_array.events == std::vector<std::string>(
        {
            "start_array()"
        }));
    }

    SECTION("JSON Lines")
    {
        SECTION("Example file")
        {
            std::stringstream ss;
            ss << R"({"name": "Gilbert", "wins": [["straight", "7♣"], ["one pair", "10♥"]]}
                    {"name": "Alexa", "wins": [["two pair", "4♠"], ["two pair", "9♠"]]}
                    {"name": "May", "wins": []}
                    {"name": "Deloise", "wins": [["three of a kind", "5♣"]]}
)";

            std::string line;
            int object_count = 0;
            while (std::getline(ss, line))
            {
                ++object_count;
                CHECK(json::accept(line));
            }

            CHECK(object_count == 4);
        }

        SECTION("Example file without trailing newline")
        {
            std::stringstream ss;
            ss << R"({"name": "Gilbert", "wins": [["straight", "7♣"], ["one pair", "10♥"]]}
                    {"name": "Alexa", "wins": [["two pair", "4♠"], ["two pair", "9♠"]]}
                    {"name": "May", "wins": []}
                    {"name": "Deloise", "wins": [["three of a kind", "5♣"]]})";

            std::string line;
            int object_count = 0;
            while (std::getline(ss, line))
            {
                ++object_count;
                CHECK(json::accept(line));
            }

            CHECK(object_count == 4);
        }
    }

    SECTION("stream position after extraction without JSON_PRECISE_STREAM_POSITION (#5340)")
    {
        // By default, the character that terminates a number is consumed, so
        // the stream is left one byte too far after a number (and only after a
        // number). JSON_PRECISE_STREAM_POSITION changes this; see
        // unit-precise-stream-position.cpp. These checks pin the default.
        const auto remaining = [](std::istream & is) -> std::string
        {
            return {std::istreambuf_iterator<char>(is), std::istreambuf_iterator<char>()};
        };

        SECTION("the character after a number is consumed")
        {
            std::istringstream ss("1true");
            json j;
            ss >> j;
            CHECK(j == 1);
            CHECK(remaining(ss) == "rue");
        }

        SECTION("the character after other values is not consumed")
        {
            std::istringstream ss("[1]true");
            json j;
            ss >> j;
            CHECK(j == json::parse("[1]"));
            CHECK(remaining(ss) == "true");
        }

        SECTION("comma-separated numbers can be read one by one")
        {
            std::istringstream ss("1,2,3");
            json j1;
            json j2;
            json j3;
            ss >> j1 >> j2 >> j3;
            CHECK(j1 == 1);
            CHECK(j2 == 2);
            CHECK(j3 == 3);
        }

        SECTION("std::getline after a number skips the line break")
        {
            std::istringstream ss("42\nfoo");
            json j;
            std::string line;
            ss >> j;
            std::getline(ss, line);
            CHECK(j == 42);
            CHECK(line == "foo");
        }
    }

    // build with C++20
    // JSON_HAS_CPP_20
#if defined(__cpp_char8_t)
    SECTION("Using _json with char8_t literals #4945")
    {
        // Regular narrow string literal
        const auto j1 = R"({"key": "value", "num": 42})"_json;
        CHECK(j1["key"] == "value");
        CHECK(j1["num"] == 42);

        // UTF-8 prefixed literal (C++20 and later); the emoji is written as a
        // \U escape rather than a raw multibyte character so this does not
        // depend on the compiler's source-file encoding (e.g., MSVC without
        // /utf-8, or classic ICC, which does not encode non-ASCII narrow
        // string literals as UTF-8 - compare against a \x-escaped expectation
        // for the same reason)
        const auto j2 = u8"{\"emoji\": \"\U0001F600\", \"msg\": \"hello\"}"_json;
        CHECK(j2["emoji"] == "\xF0\x9F\x98\x80");
        CHECK(j2["msg"] == "hello");

        const auto j3 = u8R"({"key": "value", "num": 42})"_json;
        CHECK(j3["key"] == "value");
        CHECK(j3["num"] == 42);
    }
#endif
}

#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
TEST_CASE("deserialization from a pointer and a length (deprecated)")
{
    // the unit test build disables -Wdeprecated-declarations (see
    // cmake/clang_flags.cmake)
    const std::string text = R"({"foo": [1, 2, 3]})";
    const std::string invalid = R"({"foo": )";

    SECTION("parse")
    {
        const json j = json::parse({text.data(), text.size()});
        CHECK(j == json({{"foo", {1, 2, 3}}}));
    }

    SECTION("accept")
    {
        CHECK(json::accept({text.data(), text.size()}));
        CHECK_FALSE(json::accept({invalid.data(), invalid.size()}));
    }
}
#endif

// select the types to test - char8_t is only available since C++20 if and only
// if __cpp_char8_t is defined.
#define TYPE_LIST(...) __VA_ARGS__
#if defined(__cpp_char8_t) && (__cpp_char8_t >= 201811L)
    #define ASCII_TYPES TYPE_LIST(char, wchar_t, char16_t, char32_t, char8_t)
#else
    #define ASCII_TYPES TYPE_LIST(char, wchar_t, char16_t, char32_t)
#endif

TEST_CASE_TEMPLATE("deserialization of different character types (ASCII)", T, ASCII_TYPES) // NOLINT(readability-math-missing-parentheses, bugprone-throwing-static-initialization)
{
    std::vector<T> const v = {'t', 'r', 'u', 'e'};
    CHECK(json::parse(v) == json(true));
    CHECK(json::accept(v));

    SaxEventLogger l;
    CHECK(json::sax_parse(v, &l));
    CHECK(l.events.size() == 1);
    CHECK(l.events == std::vector<std::string>({"boolean(true)"}));
}

TEST_CASE_TEMPLATE("deserialization of different character types (UTF-8)", T, char, unsigned char, std::uint8_t) // NOLINT(readability-math-missing-parentheses, bugprone-throwing-static-initialization)
{
    // a star emoji
    std::vector<T> const v = {'"', static_cast<T>(0xe2u), static_cast<T>(0xadu), static_cast<T>(0x90u), static_cast<T>(0xefu), static_cast<T>(0xb8u), static_cast<T>(0x8fu), '"'};
    CHECK(json::parse(v).dump(-1, ' ', true) == "\"\\u2b50\\ufe0f\"");
    CHECK(json::accept(v));

    SaxEventLogger l;
    CHECK(json::sax_parse(v, &l));
    CHECK(l.events.size() == 1);
}

TEST_CASE_TEMPLATE("deserialization of different character types (UTF-16)", T, char16_t) // NOLINT(readability-math-missing-parentheses, bugprone-throwing-static-initialization)
{
    // a star emoji
    std::vector<T> const v = {static_cast<T>('"'), static_cast<T>(0x2b50), static_cast<T>(0xfe0f), static_cast<T>('"')};
    CHECK(json::parse(v).dump(-1, ' ', true) == "\"\\u2b50\\ufe0f\"");
    CHECK(json::accept(v));

    SaxEventLogger l;
    CHECK(json::sax_parse(v, &l));
    CHECK(l.events.size() == 1);
}

TEST_CASE_TEMPLATE("deserialization of different character types (UTF-32)", T, char32_t) // NOLINT(readability-math-missing-parentheses, bugprone-throwing-static-initialization)
{
    // a star emoji
    std::vector<T> const v = {static_cast<T>('"'), static_cast<T>(0x2b50), static_cast<T>(0xfe0f), static_cast<T>('"')};
    CHECK(json::parse(v).dump(-1, ' ', true) == "\"\\u2b50\\ufe0f\"");
    CHECK(json::accept(v));

    SaxEventLogger l;
    CHECK(json::sax_parse(v, &l));
    CHECK(l.events.size() == 1);
}

namespace
{
// records the position and message of a parse error; reporting the error via
// SAX does not throw, so the test also runs with JSON_NOEXCEPTION
struct SaxErrorRecorder : public SaxEventLogger
{
    bool parse_error(std::size_t position, const std::string& /*last_token*/, const json::exception& ex) override
    {
        error = std::to_string(position) + " " + ex.what();
        return false;
    }

    std::string error {}; // NOLINT(readability-redundant-member-init)
};
} // namespace

TEST_CASE("parse error positions are the same for contiguous and stream input")
{
    // contiguous input derives the position from the input on error, stream
    // input counts it while reading (see lexer::lazy_position); the cases
    // cover newlines before the error, ungetting a newline after a number,
    // newlines inside a string, a comment, and reads at the end of input
    struct test_case
    {
        std::string input;
        std::size_t byte;
        std::string message;
    };
    const std::vector<test_case> cases =
    {
        {"[\n  1,\n  2\n", 12, "[json.exception.parse_error.101] parse error at line 4, column 1: syntax error while parsing array - unexpected end of input; expected ']'"},
        {"[1\n,2,\n]", 8, "[json.exception.parse_error.101] parse error at line 3, column 1: syntax error while parsing value - unexpected ']'; expected '[', '{', or a literal"},
        {"[1\n x]", 5, "[json.exception.parse_error.101] parse error at line 2, column 2: syntax error while parsing array - invalid literal; last read: '1<U+000A> x'; expected ']'"},
        {"1\n2", 3, "[json.exception.parse_error.101] parse error at line 2, column 1: syntax error while parsing value - unexpected number literal; expected end of input"},
        {
            "{\"a\":\n\"b\nc\"}", 9, R"([json.exception.parse_error.101] parse error at line 3, column 0: syntax error while parsing value - invalid string: control character U+000A (LF) must be escaped to \u000A or \n; last read: '"b<U+000A>')"
        },
        {"/* a\n b */\n x", 13, "[json.exception.parse_error.101] parse error at line 3, column 2: syntax error while parsing value - invalid literal; last read: '/* a<U+000A> b */<U+000A> x'"},
        {"\n\n", 3, "[json.exception.parse_error.101] parse error at line 3, column 1: syntax error while parsing value - unexpected end of input; expected '[', '{', or a literal"},
        {"[\"a\",\n 1e\n]", 10, "[json.exception.parse_error.101] parse error at line 3, column 0: syntax error while parsing value - invalid number; expected '+', '-', or digit after exponent; last read: '1e<U+000A>'"},
        {"[tru\n]", 5, "[json.exception.parse_error.101] parse error at line 2, column 0: syntax error while parsing value - invalid literal; last read: '[tru<U+000A>'"},
    };

    for (const auto& c : cases)
    {
        CAPTURE(c.input)
        const std::string expected = std::to_string(c.byte) + " " + c.message;

        SaxErrorRecorder string_sax;
        CHECK_FALSE(json::sax_parse(c.input, &string_sax, json::input_format_t::json, true, true));
        CHECK(string_sax.error == expected);

        SaxErrorRecorder pointer_sax;
        CHECK_FALSE(json::sax_parse(c.input.data(), c.input.data() + c.input.size(), &pointer_sax, json::input_format_t::json, true, true));
        CHECK(pointer_sax.error == expected);

        std::istringstream is(c.input);
        SaxErrorRecorder stream_sax;
        CHECK_FALSE(json::sax_parse(is, &stream_sax, json::input_format_t::json, true, true));
        CHECK(stream_sax.error == expected);
    }
}

#if !defined(JSON_NOEXCEPTION)
TEST_CASE("indentation runs of every length around the 8-byte skip")
{
    // contiguous input skips the spaces after a newline 8 bytes at a time (see
    // lexer::skip_indentation), stream input reads them one by one; results,
    // byte offsets, and messages must be the same for runs that end anywhere
    // relative to a word boundary, including at the end of the input
    const auto parse_result = [](const std::string & input, bool contiguous)
    {
        try
        {
            if (contiguous)
            {
                return json::parse(input.data(), input.data() + input.size(), nullptr, true, true).dump();
            }
            std::istringstream is(input);
            return json::parse(is, nullptr, true, true).dump();
        }
        catch (const json::parse_error& e)
        {
            return std::to_string(e.byte).append(" ").append(e.what());
        }
    };

    // replace every '~' in a pattern by an indentation run
    const auto indented = [](const std::string & pattern, const std::string & indent)
    {
        std::string result;
        for (const char c : pattern)
        {
            if (c == '~')
            {
                result += indent;
            }
            else
            {
                result += c;
            }
        }
        return result;
    };

    const std::vector<std::string> patterns =
    {
        "[\n~1,\n~2\n]",
        "[\n~1,\n~x]",
        "[\n~1,\n~",
        "1\n~",
        "[\n~\t1,\n~\r\n~2]",
        "[\n~/* c */ 1]",
        "[\n~1\n~2]",
    };

    for (std::size_t n = 0; n <= 33; ++n)
    {
        const std::string indent(n, ' ');
        for (const auto& pattern : patterns)
        {
            const std::string input = indented(pattern, indent);
            CAPTURE(n)
            CAPTURE(input)
            const std::string expected = parse_result(input, false);
            CHECK(parse_result(input, true) == expected);
            CHECK(json::accept(input.data(), input.data() + input.size(), true) == json::accept(input, true));
        }
    }

    // and against fixed expectations, in case both paths broke the same way
    CHECK(parse_result(indented("[\n~x]", std::string(16, ' ')), true) == "19 [json.exception.parse_error.101] parse error at line 2, column 17: syntax error while parsing value - invalid literal; last read: '[<U+000A>                x'");
    CHECK(parse_result(indented("[\n~1]", std::string(17, ' ')), true) == "[1]");
}
#endif

#if !defined(JSON_NOEXCEPTION)
namespace
{
/// the value of parsing [first, last), or the message of the exception
template<typename Iterator>
std::string outcome_of(Iterator first, Iterator last)
{
    try
    {
        return json::parse(first, last).dump();
    }
    catch (const json::exception& e)
    {
        return e.what();
    }
}

/// the bytes of @a text as a vector of @a T (explicit casts: no implicit char conversion)
template<typename T>
std::vector<T> bytes_as(const std::string& text)
{
    std::vector<T> result;
    result.reserve(text.size());
    for (const char c : text)
    {
        result.push_back(static_cast<T>(c));
    }
    return result;
}

/// a std::string, std::vector<char>, <unsigned char> and <signed char> as
/// iterator pairs: the same as the byte path (std::list iterators)
void check_iterator_pairs(const std::string& text)
{
    CAPTURE(text)
    const std::list<char> bytes(text.begin(), text.end());
    const std::string expected = outcome_of(bytes.begin(), bytes.end());
    const bool expected_accept = json::accept(bytes.begin(), bytes.end());

    std::string s = text;
    CHECK(outcome_of(s.begin(), s.end()) == expected);
    CHECK(outcome_of(s.cbegin(), s.cend()) == expected);
    CHECK(json::accept(s.cbegin(), s.cend()) == expected_accept);

    const std::vector<char> vc(text.begin(), text.end());
    CHECK(outcome_of(vc.begin(), vc.end()) == expected);
    const std::vector<unsigned char> vu = bytes_as<unsigned char>(text);
    CHECK(outcome_of(vu.begin(), vu.end()) == expected);
    CHECK(json::accept(vu.begin(), vu.end()) == expected_accept);
    const std::vector<signed char> vs = bytes_as<signed char>(text);
    CHECK(outcome_of(vs.begin(), vs.end()) == expected);
}
}  // namespace

TEST_CASE("deserialization from iterator pairs of std::string and std::vector")
{
    // these are read as the pointer range they are, also before C++20
    for (const char* text :
            {
                "", " ", R"([1, 2.5, "a", true, null, {"k": ["v"]}])", "[1, 2", R"({"a" 1})", "\"\xC3\xA4\"", "\"\xC3\"", "[1]x", "1e400"
            })
    {
        check_iterator_pairs(text);
    }
    check_iterator_pairs(std::string("[1]" "\0" "x", 5));

    // an empty range is not dereferenced
    std::string empty;
    CHECK_FALSE(json::accept(empty.begin(), empty.end()));
    json _;
    CHECK_THROWS_AS(_ = json::parse(empty.begin(), empty.end()), json::parse_error&);
}
#endif