Function decode

include/jwt-cpp/base.h:228–272

			}

			inline std::string decode(const std::string& base, const std::array<int8_t, 256>& rdata,
									  const std::vector<std::string>& fill) {
				const auto pad = count_padding(base, fill);
				if (pad.count > 2) throw std::runtime_error("Invalid input: too much fill");

				const size_t size = base.size() - pad.length;
				if ((size + pad.count) % 4 != 0) throw std::runtime_error("Invalid input: incorrect total size");

				size_t out_size = size / 4 * 3;
				std::string res;
				res.reserve(out_size);

				auto get_sextet = [&](size_t offset) { return alphabet::index(rdata, base[offset]); };

				size_t fast_size = size - size % 4;
				for (size_t i = 0; i < fast_size;) {
					uint32_t sextet_a = get_sextet(i++);
					uint32_t sextet_b = get_sextet(i++);
					uint32_t sextet_c = get_sextet(i++);
					uint32_t sextet_d = get_sextet(i++);

					uint32_t triple =
						(sextet_a << 3 * 6) + (sextet_b << 2 * 6) + (sextet_c << 1 * 6) + (sextet_d << 0 * 6);

					res += static_cast<char>((triple >> 2 * 8) & 0xFFU);
					res += static_cast<char>((triple >> 1 * 8) & 0xFFU);
					res += static_cast<char>((triple >> 0 * 8) & 0xFFU);
				}

				if (pad.count == 0) return res;

				uint32_t triple = (get_sextet(fast_size) << 3 * 6) + (get_sextet(fast_size + 1) << 2 * 6);

				switch (pad.count) {
				case 1:
					triple |= (get_sextet(fast_size + 2) << 1 * 6);
					res += static_cast<char>((triple >> 2 * 8) & 0xFFU);
					res += static_cast<char>((triple >> 1 * 8) & 0xFFU);
					break;
				case 2: res += static_cast<char>((triple >> 2 * 8) & 0xFFU); break;
				default: break;
				}

				return res;
			}

			inline std::string decode(const std::string& base, const std::array<int8_t, 256>& rdata,
									  const std::string& fill) {