text: //
  // ip/network_v6.hpp
  // ~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  // Copyright (c) 2014 Oliver Kowalke (oliver dot kowalke at gmail dot com)
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  #ifndef ASIO_IP_NETWORK_V6_HPP
  #define ASIO_IP_NETWORK_V6_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include "asio/detail/config.hpp"
  #include <string>
  #include "asio/detail/string_view.hpp"
  #include "asio/error_code.hpp"
  #include "asio/ip/address_v6_range.hpp"
  
  #include "asio/detail/push_options.hpp"
  
  namespace asio {
  namespace ip {
  
  /// Represents an IPv6 network.
  /**
   * The asio::ip::network_v6 class provides the ability to use and
   * manipulate IP version 6 networks.
   *
   * @par Thread Safety
   * @e Distinct @e objects: Safe.@n
   * @e Shared @e objects: Unsafe.
   */
  class network_v6
  {
  public:
    /// Default constructor.
    network_v6() ASIO_NOEXCEPT
      : address_(),
        prefix_length_(0)
    {
    }
  
    /// Construct a network based on the specified address and prefix length.
    ASIO_DECL network_v6(const address_v6& addr,
        unsigned short prefix_len);
  
    /// Copy constructor.
    network_v6(const network_v6& other) ASIO_NOEXCEPT
      : address_(other.address_),
        prefix_length_(other.prefix_length_)
    {
    }
  
  #if defined(ASIO_HAS_MOVE)
    /// Move constructor.
    network_v6(network_v6&& other) ASIO_NOEXCEPT
      : address_(ASIO_MOVE_CAST(address_v6)(other.address_)),
        prefix_length_(other.prefix_length_)
    {
    }
  #endif // defined(ASIO_HAS_MOVE)
  
    /// Assign from another network.
    network_v6& operator=(const network_v6& other) ASIO_NOEXCEPT
    {
      address_ = other.address_;
      prefix_length_ = other.prefix_length_;
      return *this;
    }
  
  #if defined(ASIO_HAS_MOVE)
    /// Move-assign from another network.
    network_v6& operator=(network_v6&& other) ASIO_NOEXCEPT
    {
      address_ = ASIO_MOVE_CAST(address_v6)(other.address_);
      prefix_length_ = other.prefix_length_;
      return *this;
    }
  #endif // defined(ASIO_HAS_MOVE)
  
    /// Obtain the address object specified when the network object was created.
    address_v6 address() const ASIO_NOEXCEPT
    {
      return address_;
    }
  
    /// Obtain the prefix length that was specified when the network object was
    /// created.
    unsigned short prefix_length() const ASIO_NOEXCEPT
    {
      return prefix_length_;
    }
  
    /// Obtain an address object that represents the network address.
    ASIO_DECL address_v6 network() const ASIO_NOEXCEPT;
  
    /// Obtain an address range corresponding to the hosts in the network.
    ASIO_DECL address_v6_range hosts() const ASIO_NOEXCEPT;
  
    /// Obtain the true network address, omitting any host bits.
    network_v6 canonical() const ASIO_NOEXCEPT
    {
      return network_v6(network(), prefix_length());
    }
  
    /// Test if network is a valid host address.
    bool is_host() const ASIO_NOEXCEPT
    {
      return prefix_length_ == 128;
    }
  
    /// Test if a network is a real subnet of another network.
    ASIO_DECL bool is_subnet_of(const network_v6& other) const;
  
    /// Get the network as an address in dotted decimal format.
    ASIO_DECL std::string to_string() const;
  
    /// Get the network as an address in dotted decimal format.
    ASIO_DECL std::string to_string(asio::error_code& ec) const;
  
    /// Compare two networks for equality.
    friend bool operator==(const network_v6& a, const network_v6& b)
    {
      return a.address_ == b.address_ && a.prefix_length_ == b.prefix_length_;
    }
  
    /// Compare two networks for inequality.
    friend bool operator!=(const network_v6& a, const network_v6& b)
    {
      return !(a == b);
    }
  
  private:
    address_v6 address_;
    unsigned short prefix_length_;
  };
  
  /// Create an IPv6 network from an address and prefix length.
  /**
   * @relates address_v6
   */
  inline network_v6 make_network_v6(
      const address_v6& addr, unsigned short prefix_len)
  {
    return network_v6(addr, prefix_len);
  }
  
  /// Create an IPv6 network from a string containing IP address and prefix
  /// length.
  /**
   * @relates network_v6
   */
  ASIO_DECL network_v6 make_network_v6(const char* str);
  
  /// Create an IPv6 network from a string containing IP address and prefix
  /// length.
  /**
   * @relates network_v6
   */
  ASIO_DECL network_v6 make_network_v6(
      const char* str, asio::error_code& ec);
  
  /// Create an IPv6 network from a string containing IP address and prefix
  /// length.
  /**
   * @relates network_v6
   */
  ASIO_DECL network_v6 make_network_v6(const std::string& str);
  
  /// Create an IPv6 network from a string containing IP address and prefix
  /// length.
  /**
   * @relates network_v6
   */
  ASIO_DECL network_v6 make_network_v6(
      const std::string& str, asio::error_code& ec);
  
  #if defined(ASIO_HAS_STRING_VIEW) \
    || defined(GENERATING_DOCUMENTATION)
  
  /// Create an IPv6 network from a string containing IP address and prefix
  /// length.
  /**
   * @relates network_v6
   */
  ASIO_DECL network_v6 make_network_v6(string_view str);
  
  /// Create an IPv6 network from a string containing IP address and prefix
  /// length.
  /**
   * @relates network_v6
   */
  ASIO_DECL network_v6 make_network_v6(
      string_view str, asio::error_code& ec);
  
  #endif // defined(ASIO_HAS_STRING_VIEW)
         //  || defined(GENERATING_DOCUMENTATION)
  
  #if !defined(ASIO_NO_IOSTREAM)
  
  /// Output a network as a string.
  /**
   * Used to output a human-readable string for a specified network.
   *
   * @param os The output stream to which the string will be written.
   *
   * @param net The network to be written.
   *
   * @return The output stream.
   *
   * @relates asio::ip::address_v6
   */
  template <typename Elem, typename Traits>
  std::basic_ostream<Elem, Traits>& operator<<(
      std::basic_ostream<Elem, Traits>& os, const network_v6& net);
  
  #endif // !defined(ASIO_NO_IOSTREAM)
  
  } // namespace ip
  } // namespace asio
  
  #include "asio/detail/pop_options.hpp"
  
  #include "asio/ip/impl/network_v6.hpp"
  #if defined(ASIO_HEADER_ONLY)
  # include "asio/ip/impl/network_v6.ipp"
  #endif // defined(ASIO_HEADER_ONLY)
  
  #endif // ASIO_IP_NETWORK_V6_HPP
  