logger_fwd.h

// Description: Logger class
// Detail: An abstract base class for reporting logging information
// Documentation: loggers.txt

#ifndef PASTELSYS_LOGGER_FWD_H
#define PASTELSYS_LOGGER_FWD_H

#include <string>
#include <unordered_set>

namespace Pastel
{

    class Log;

    class Logger
    {
    public:
        // Using default constructor.
        // Using default copy constructor.
        // Using default assignment.
        // Using default destructor.

        virtual ~Logger();

        void swap(Logger& that);

        //! Write a string.
        virtual Logger& operator<<(
            const std::string& value) = 0;

        //! Frees any resources.
        /*!
       This is called, for example, before aborting
       program execution via an assertion. With this
       function the logger has the chance to close 
       a file or flush the contents of a stream.
       */
        virtual void finalize() = 0;

    private:
        friend class Log;

        //! Add a log to the set of observer logs.
        void addLog(Log* log);

        //! Remove a log from the set of observer logs.
        void removeLog(Log* log);

        using LogSet = std::unordered_set<Log*>;
        using Log_Iterator = LogSet::iterator;
        using Log_ConstIterator = LogSet::const_iterator;

        //! The set of observer logs.
        LogSet logSet_;
    };

}

#endif