AC_Sprayer: add singleton

libraries/AC_Sprayer/AC_Sprayer.cpp

@@ -50,6 +50,14 @@ const AP_Param::GroupInfo AC_Sprayer::var_info[] = {
 
 AC_Sprayer::AC_Sprayer()
 {
+    if (_s_instance) {
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+        AP_HAL::panic("Too many sprayers");
+#endif
+        return;
+    }
+    _s_instance = this;
+
     AP_Param::setup_object_defaults(this, var_info);
 
     // check for silly parameter values
@@ -63,6 +71,15 @@ AC_Sprayer::AC_Sprayer()
     // To-Do: ensure that the pump and spinner servo channels are enabled
 }
 
+/*
+ * Get the AP_Sprayer singleton
+ */
+AC_Sprayer *AC_Sprayer::_s_instance = nullptr;
+AC_Sprayer *AC_Sprayer::get_instance()
+{
+    return _s_instance;
+}
+
 void AC_Sprayer::run(const bool true_false)
 {
     // return immediately if no change
@@ -168,3 +185,12 @@ void AC_Sprayer::update()
         stop_spraying();
     }
 }
+
+namespace AP {
+
+AC_Sprayer *sprayer()
+{
+    return AC_Sprayer::get_instance();
+}
+
+};

libraries/AC_Sprayer/AC_Sprayer.h

@@ -38,6 +38,9 @@ public:
     AC_Sprayer(const AC_Sprayer &other) = delete;
     AC_Sprayer &operator=(const AC_Sprayer&) = delete;
 
+    static AC_Sprayer *get_instance();
+    static AC_Sprayer *_s_instance;
+
     /// run - allow or disallow spraying to occur
     void run(bool true_false);
 
@@ -82,3 +85,7 @@ private:
 
     void stop_spraying();
 };
+
+namespace AP {
+    AC_Sprayer *sprayer();
+};