virtual size_t read_some()

in src/native/io/sequential/chain_reader.h [72:129]

• 45 lines of code
• 7 McCabe index (conditional complexity)

	virtual size_t read_some(std::span<char> buffer)
	{
		size_t total_read{};

		auto remaining_to_read = buffer.size();

		while (remaining_to_read > 0)
		{
			if (m_current_reader_index >= m_readers.size())
			{
				break;
			}

			auto &current_reader = m_readers[m_current_reader_index];

			std::span<char> reader_buffer{buffer.data() + total_read, buffer.size() - total_read};
			auto actual_read = current_reader->read_some(reader_buffer);

			if (actual_read == 0)
			{
				// shouldn't be possible
				std::string msg = "chain_reader::read_some: Couldn't read any data. remaining_to_read: "
				                + std::to_string(remaining_to_read);
				throw errors::user_exception(errors::error_code::io_chain_read_too_much, msg);
			}

			if (actual_read > remaining_to_read)
			{
				// shouldn't be possible
				std::string msg =
					"chain_reader::read_some: More read than remaining. actual_read: " + std::to_string(actual_read)
					+ ", remaining_to_read: " + std::to_string(remaining_to_read);
				throw errors::user_exception(errors::error_code::io_chain_read_too_much, msg);
			}

			total_read += actual_read;
			m_read_offset += actual_read;
			m_offset_in_current_reader += actual_read;
			remaining_to_read -= actual_read;

			if (current_reader->tellg() > current_reader->size())
			{
				std::string msg =
					"chain_reader::read_some: tellg() > size(). tellg: " + std::to_string(current_reader->tellg())
					+ ", size(): " + std::to_string(current_reader->size());
				throw errors::user_exception(errors::error_code::io_chain_bad_offset, msg);
			}

			// just move to next reader, we're done here.
			if (current_reader->tellg() == current_reader->size())
			{
				m_offset_in_current_reader = 0;
				m_current_reader_index++;
			}
		}

		return total_read;
	}