Function readJSONObjectPossiblyInvalid

src/IO/ReadHelpers.cpp:1075–1133

template <typename Vector, typename ReturnType>
ReturnType readJSONObjectPossiblyInvalid(Vector & s, ReadBuffer & buf)
{
    static constexpr bool throw_exception = std::is_same_v<ReturnType, void>;

    auto error = [](const char * message [[maybe_unused]], int code [[maybe_unused]])
    {
        if constexpr (throw_exception)
            throw ParsingException(code, std::move(message));
        return ReturnType(false);
    };

    if (buf.eof() || *buf.position() != '{')
        return error("JSON should start from opening curly bracket", ErrorCodes::INCORRECT_DATA);

    s.push_back(*buf.position());
    ++buf.position();

    Int64 balance = 1;
    bool quotes = false;

    while (!buf.eof())
    {
        char * next_pos = find_first_symbols<'\\', '{', '}', '"'>(buf.position(), buf.buffer().end());
        appendToStringOrVector(s, buf, next_pos);
        buf.position() = next_pos;

        if (!buf.hasPendingData())
            continue;

        s.push_back(*buf.position());

        if (*buf.position() == '\\')
        {
            ++buf.position();
            if (!buf.eof())
            {
                s.push_back(*buf.position());
                ++buf.position();
            }

            continue;
        }

        if (*buf.position() == '"')
            quotes = !quotes;
        else if (!quotes) // can be only '{' or '}'
            balance += *buf.position() == '{' ? 1 : -1;

        ++buf.position();

        if (balance == 0)
            return ReturnType(true);

        if (balance <    0)
            break;
    }

    return error("JSON should have equal number of opening and closing brackets", ErrorCodes::INCORRECT_DATA);