TransceiverBase.h

#ifndef TRANSCEIVER_BASE_HPP__
#define TRANSCEIVER_BASE_HPP__
 
#include "Transceiver.h"
 
#include <QLoggingCategory>
#include <QString>
 
#include <stdexcept>
 
//
// Base Transceiver Implementation
//
//  Behaviour common to all Transceiver implementations.
//
// Collaborations
//
//  Implements the Transceiver abstract  interface as template methods
//  and provides  a new abstract interface  with similar functionality
//  (do_XXXXX operations). Provides and  calls abstract interface that
//  gets  called post  the above  operations (do_post_XXXXX)  to allow
//  caching implementation etc.
//
//  A  key factor  is  to  catch all  exceptions  thrown by  sub-class
//  implementations where  the template method  is a Qt slot  which is
//  therefore  likely  to  be  called   by  Qt  which  doesn't  handle
//  exceptions. Any exceptions are converted to Transceiver::failure()
//  signals.
//
//  Sub-classes update the stored state via a protected interface.
//
// Responsibilities:
//
//  Wrap incoming  Transceiver messages catching all  exceptions in Qt
//  slot driven  messages and converting  them to Qt signals.  This is
//  done because exceptions  make concrete Transceiver implementations
//  simpler  to   write,  but  exceptions  cannot   cross  signal/slot
//  boundaries  (especially across  threads).  This  also removes  any
//  requirement for the client code to handle exceptions.
//
//  Maintain the  state of the  concrete Transceiver instance  that is
//  passed back via  the Transceiver::update(TransceiverState) signal,
//  it   is  still   the   responsibility   of  concrete   Transceiver
//  implementations to emit  the state_change signal when  they have a
//  status update.
//
//  Maintain    a   go/no-go    status   for    concrete   Transceiver
//  implementations  ensuring only  a valid  sequence of  messages are
//  passed. A concrete Transceiver instance  must be started before it
//  can receive  messages, any exception thrown  takes the Transceiver
//  offline.
//
//  Implements methods  that concrete Transceiver  implementations use
//  to update the Transceiver state.  These do not signal state change
//  to  clients  as  this  is   the  responsibility  of  the  concrete
//  Transceiver implementation, thus allowing multiple state component
//  updates to be signalled together if required.
//
class TransceiverBase : public Transceiver {
    Q_OBJECT;
 
  protected:
    TransceiverBase(QObject *parent)
        : Transceiver{parent}, last_sequence_number_{0} {}
 
  public:
    //
    // Implement the Transceiver abstract interface.
    //
    void start(unsigned sequence_number) noexcept override final;
    void set(TransceiverState const &,
             unsigned sequence_number) noexcept override final;
    void stop() noexcept override final;
 
    //
    // Query operations
    //
    TransceiverState const &state() const { return actual_; }
 
  protected:
    //
    // Error exception which is thrown to signal unexpected errors.
    //
    struct error : public std::runtime_error {
        explicit error(char const *const msg) : std::runtime_error(msg) {}
        explicit error(QString const &msg)
            : std::runtime_error(msg.toStdString()) {}
    };
 
    // Template methods that sub classes implement to do what they need to do.
    //
    // These methods may throw exceptions to signal errors.
    virtual int
    do_start() = 0; // returns resolution, See Transceiver::resolution
    virtual void do_post_start() {}
 
    virtual void do_stop() = 0;
    virtual void do_post_stop() {}
 
    virtual void do_frequency(Frequency, MODE, bool no_ignore) = 0;
    virtual void do_post_frequency(Frequency, MODE) {}

    inline virtual void hamlib_bug_bandaid(TransceiverState const &) {};
    virtual void do_tx_frequency(Frequency, MODE, bool no_ignore) = 0;
    virtual void do_post_tx_frequency(Frequency, MODE) {}
 
    virtual void do_mode(MODE) = 0;
    virtual void do_post_mode(MODE) {}
 
    virtual void do_ptt(bool = true) = 0;
    virtual void do_post_ptt(bool = true) {}
 
    virtual void do_sync(bool force_signal = false, bool no_poll = false) = 0;
 
    virtual bool do_pre_update() { return true; }
 
    // sub classes report rig state changes with these methods
    void update_rx_frequency(Frequency);
    void update_other_frequency(Frequency = 0);
    void update_split(bool);
    void update_mode(MODE);
    void update_PTT(bool = true);
 
    // Calling this eventually triggers the Transceiver::update(State) signal.
    void update_complete(bool force_signal = false);
 
    // sub class may asynchronously take the rig offline by calling this
    void offline(QString const &reason);
 
  private:
    void startup();
    void shutdown();
    bool maybe_low_resolution(Frequency low_res, Frequency high_res);
 
    // use this convenience class to notify in update methods
    class may_update {
      public:
        explicit may_update(TransceiverBase *self, bool force_signal = false)
            : self_{self}, force_signal_{force_signal} {}
        ~may_update() { self_->update_complete(force_signal_); }
 
      private:
        TransceiverBase *self_;
        bool force_signal_;
    };
 
    TransceiverState requested_;
    TransceiverState actual_;
    TransceiverState last_;
    unsigned last_sequence_number_; // from set state operation
};
 
// some trace macros
Q_DECLARE_LOGGING_CATEGORY(transceiverbase_js8)
#define TRACE_CAT(FAC, MSG)                                                    \
    qCDebug(transceiverbase_js8)                                               \
        << QString{"%1::%2:"}.arg((FAC)).arg(__func__) << MSG
#define TRACE_CAT_POLL(FAC, MSG)                                               \
    qCDebug(transceiverbase_js8)                                               \
        << QString{"%1::%2:"}.arg((FAC)).arg(__func__) << MSG
 
#endif