## Class template channel_severity_filter_actor

boost::log::expressions::channel_severity_filter_actor

## Synopsis

    // In header: <boost/log/expressions/predicates/channel_severity_filter.hpp>

    template<typename ChannelT, typename SeverityT,
             typename ChannelFallbackT = fallback_to_none,
             typename SeverityFallbackT = fallback_to_none,
             typename ChannelOrderT = less,
             typename SeverityCompareT = greater_equal,
             typename AllocatorT = std::allocator< void >,
             template< typename > class ActorT = phoenix::actor>
    class channel_severity_filter_actor : public ActorT< channel_severity_filter_terminal< ChannelT, SeverityT, ChannelFallbackT, SeverityFallbackT, ChannelOrderT, SeverityCompareT, AllocatorT > >
    {
    public:
      // types
      typedef channel_severity_filter_terminal< ChannelT, SeverityT, ChannelFallbackT, SeverityFallbackT, ChannelOrderT, SeverityCompareT, AllocatorT > terminal_type;             // Terminal type.
      typedef ActorT< terminal_type >                                                                                                                   base_type;                 // Base actor type.
      typedef terminal_type::channel_value_type                                                                                                         channel_value_type;        // Channel attribute value type.
      typedef terminal_type::channel_fallback_policy                                                                                                    channel_fallback_policy;   // Channel fallback policy.
      typedef terminal_type::severity_value_type                                                                                                        severity_value_type;       // Severity level attribute value type.
      typedef terminal_type::severity_fallback_policy                                                                                                   severity_fallback_policy;  // Severity level fallback policy.

      // member classes/structs/unions

      // An auxiliary pseudo-reference to implement insertion through subscript
      // operator.

      class subscript_result {
      public:
        // construct/copy/destruct
        subscript_result(channel_severity_filter_actor &,
                         channel_value_type const &);
        void operator=(severity_value_type const &);
      };

      // construct/copy/destruct
      explicit channel_severity_filter_actor(base_type const &);
      channel_severity_filter_actor(channel_severity_filter_actor const &);

      // public member functions
      this_type & set_default(bool);
      this_type & add(channel_value_type const &, severity_value_type const &);
      subscript_result operator[](channel_value_type const &);
    };

## Description

### `channel_severity_filter_actor` public construct/copy/destruct

1.     explicit channel_severity_filter_actor(base_type const & act);

   Initializing constructor.

2.     channel_severity_filter_actor(channel_severity_filter_actor const & that);

   Copy constructor.

### `channel_severity_filter_actor` public member functions

1.     this_type & set_default(bool def);

   Sets the default function result.

2.     this_type & add(channel_value_type const & channel,
                       severity_value_type const & severity);

   Adds a new element to the mapping.

3.     subscript_result operator[](channel_value_type const & channel);

   Alternative interface for adding a new element to the mapping.