base_n::decode_algorithm::read

template <meta::output_iterator<element_type> O>
std::pair<O, mgs::ssize_t> read(O dst, mgs::ssize_t n);

Fills dst with at most n bytes of decoded output, returning a pair containing the new value of dst and the number of bytes written.

---

Template parameters

Name	Description
O	Output iterator where decoded bytes will be written. Must model meta::output_iterator<element_type>.

Parameters

• dst - output iterator

• n - maximum number of bytes to write

Return value

A pair containing the new position of dst, and the number of bytes written.

Example

#include <iostream>
#include <string>

#include <mgs/base_n/decode_algorithm.hpp>
#include <mgs/codecs/iterator_sentinel_source.hpp>

using namespace mgs;
using namespace mgs::base_n;

namespace {

struct base2_encoding_traits {
  // using C++17 inline variables for simplicity
  inline static char const alphabet[] = {'0', '1'};
  inline static auto const padding_policy = base_n::padding_policy::none;

  static int index_of(char c) {
    if (c == '0') return 0;
    if (c == '1') return 1;
    return -1;
  }
};

}  // namespace

int main() {
  using input_source_t =
      codecs::iterator_sentinel_source<std::string::iterator>;
  using base2_decode = decode_algorithm<base2_encoding_traits, input_source_t>;

  std::string hello(
      "01001000"
      "01100101"
      "01101100"
      "01101100"
      "01101111"
      "00101100"
      "00100000"
      "01010111"
      "01101111"
      "01110010"
      "01101100"
      "01100100"
      "00100001");
  auto input_source = codecs::make_iterator_sentinel_source(hello);

  base2_decode algo(input_source);
  std::string buffer(1024, 0);

  auto it = &buffer[0];
  auto size_to_read = buffer.size();
  auto total_read = 0;
  for (auto res = algo.read(it, size_to_read); res.second != 0;
       res = algo.read(it, size_to_read)) {
    it = res.first;
    size_to_read -= res.second;
    total_read += res.second;
  }
  buffer.resize(total_read);
  std::cout << buffer << std::endl;
}