Method send_with_content_provider

external/httplib.h:7774–7851

}

inline std::unique_ptr<Response> ClientImpl::send_with_content_provider(
    Request &req, const char *body, size_t content_length,
    ContentProvider content_provider,
    ContentProviderWithoutLength content_provider_without_length,
    const std::string &content_type, Error &error) {
  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

#ifdef CPPHTTPLIB_ZLIB_SUPPORT
  if (compress_) { req.set_header("Content-Encoding", "gzip"); }
#endif

#ifdef CPPHTTPLIB_ZLIB_SUPPORT
  if (compress_ && !content_provider_without_length) {
    // TODO: Brotli support
    detail::gzip_compressor compressor;

    if (content_provider) {
      auto ok = true;
      size_t offset = 0;
      DataSink data_sink;

      data_sink.write = [&](const char *data, size_t data_len) -> bool {
        if (ok) {
          auto last = offset + data_len == content_length;

          auto ret = compressor.compress(
              data, data_len, last,
              [&](const char *compressed_data, size_t compressed_data_len) {
                req.body.append(compressed_data, compressed_data_len);
                return true;
              });

          if (ret) {
            offset += data_len;
          } else {
            ok = false;
          }
        }
        return ok;
      };

      while (ok && offset < content_length) {
        if (!content_provider(offset, content_length - offset, data_sink)) {
          error = Error::Canceled;
          return nullptr;
        }
      }
    } else {
      if (!compressor.compress(body, content_length, true,
                               [&](const char *data, size_t data_len) {
                                 req.body.append(data, data_len);
                                 return true;
                               })) {
        error = Error::Compression;
        return nullptr;
      }
    }
  } else