text: // Copyright (c) 2017-2019, BITRUBCOIN, The Monero Project
  //
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without modification, are
  // permitted provided that the following conditions are met:
  //
  // 1. Redistributions of source code must retain the above copyright notice, this list of
  //    conditions and the following disclaimer.
  //
  // 2. Redistributions in binary form must reproduce the above copyright notice, this list
  //    of conditions and the following disclaimer in the documentation and/or other
  //    materials provided with the distribution.
  //
  // 3. Neither the name of the copyright holder nor the names of its contributors may be
  //    used to endorse or promote products derived from this software without specific
  //    prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
  // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
  // THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
  // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #pragma once
  
  #include <array>
  #include <cstdint>
  #include <iosfwd>
  #include <string>
  
  #include "wipeable_string.h"
  #include "span.h"
  
  namespace epee
  {
    struct to_hex
    {
      //! \return A std::string containing hex of `src`.
      static std::string string(const span<const std::uint8_t> src);
      //! \return A epee::wipeable_string containing hex of `src`.
      static epee::wipeable_string wipeable_string(const span<const std::uint8_t> src);
      template<typename T> static epee::wipeable_string wipeable_string(const T &pod) { return wipeable_string(span<const uint8_t>((const uint8_t*)&pod, sizeof(pod))); }
  
      //! \return An array containing hex of `src`.
      template<std::size_t N>
      static std::array<char, N * 2> array(const std::array<std::uint8_t, N>& src) noexcept
      {
        std::array<char, N * 2> out{{}};
        static_assert(N <= 128, "keep the stack size down");
        buffer_unchecked(out.data(), {src.data(), src.size()});
        return out;
      }
  
      //! Append `src` as hex to `out`.
      static void buffer(std::ostream& out, const span<const std::uint8_t> src);
  
      //! Append `< + src + >` as hex to `out`.
      static void formatted(std::ostream& out, const span<const std::uint8_t> src);
  
    private:
      template<typename T> T static convert(const span<const std::uint8_t> src);
  
      //! Write `src` bytes as hex to `out`. `out` must be twice the length
      static void buffer_unchecked(char* out, const span<const std::uint8_t> src) noexcept;
    };
  }
  