Function contains

Source/external/json.hpp:14259–14336

	*/
	template<typename BasicJsonType>
	bool contains(const BasicJsonType* ptr) const
	{
		for (const auto& reference_token : reference_tokens)
		{
			switch (ptr->type())
			{
				case detail::value_t::object:
				{
					if (!ptr->contains(reference_token))
					{
						// we did not find the key in the object
						return false;
					}

					ptr = &ptr->operator[](reference_token);
					break;
				}

				case detail::value_t::array:
				{
					if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
					{
						// "-" always fails the range check
						return false;
					}
					if (JSON_HEDLEY_UNLIKELY(reference_token.size() == 1 && !("0" <= reference_token && reference_token <= "9")))
					{
						// invalid char
						return false;
					}
					if (JSON_HEDLEY_UNLIKELY(reference_token.size() > 1))
					{
						if (JSON_HEDLEY_UNLIKELY(!('1' <= reference_token[0] && reference_token[0] <= '9')))
						{
							// first char should be between '1' and '9'
							return false;
						}
						for (std::size_t i = 1; i < reference_token.size(); i++)
						{
							if (JSON_HEDLEY_UNLIKELY(!('0' <= reference_token[i] && reference_token[i] <= '9')))
							{
								// other char should be between '0' and '9'
								return false;
							}
						}
					}

					const auto idx = array_index<BasicJsonType>(reference_token);
					if (idx >= ptr->size())
					{
						// index out of range
						return false;
					}

					ptr = &ptr->operator[](idx);
					break;
				}