AP_Vehicle: add singleton

libraries/AP_Vehicle/AP_Vehicle.cpp

@@ -0,0 +1,18 @@
+#include <AP_Vehicle/AP_Vehicle.h>
+
+AP_Vehicle *AP_Vehicle::_singleton = nullptr;
+
+AP_Vehicle *AP_Vehicle::get_singleton()
+{
+    return _singleton;
+}
+
+namespace AP {
+
+AP_Vehicle *vehicle()
+{
+    return AP_Vehicle::get_singleton();
+}
+
+};
+

libraries/AP_Vehicle/AP_Vehicle.h

@@ -36,7 +36,18 @@ class AP_Vehicle : public AP_HAL::HAL::Callbacks {
 
 public:
 
-    AP_Vehicle() {}
+    AP_Vehicle() {
+        if (_singleton) {
+            AP_HAL::panic("Too many Vehicles");
+        }
+        _singleton = this;
+    }
+
+    /* Do not allow copies */
+    AP_Vehicle(const AP_Vehicle &other) = delete;
+    AP_Vehicle &operator=(const AP_Vehicle&) = delete;
+
+    static AP_Vehicle *get_singleton();
 
     /*
       common parameters for fixed wing aircraft
@@ -121,6 +132,14 @@ protected:
     // false disables external leds)
     AP_Notify notify;
 
+private:
+
+    static AP_Vehicle *_singleton;
+
+};
+
+namespace AP {
+    AP_Vehicle *vehicle();
 };
 
 extern const AP_HAL::HAL& hal;