Allow Command-manager singleton to be deleted.

[simgear.git] / simgear / structure / SGSharedPtr.hxx

diff --git a/simgear/structure/SGSharedPtr.hxx b/simgear/structure/SGSharedPtr.hxx
index 98b72f22c902a37dfd43c07b2f8418a36687ebbe..081d5eb943b1bcb43cf89661228b4477ea94a7ab 100644 (file)
--- a/simgear/structure/SGSharedPtr.hxx
+++ b/simgear/structure/SGSharedPtr.hxx
@@ -1,6 +1,6 @@
 /* -*-c++-*-
  *
- * Copyright (C) 2005-2009 Mathias Froehlich 
+ * Copyright (C) 2005-2012 Mathias Froehlich 
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -48,6 +48,8 @@ class SGWeakPtr;
 template<typename T>
 class SGSharedPtr {
 public:
+  typedef T element_type;
+
   SGSharedPtr(void) : _ptr(0)
   {}
   SGSharedPtr(T* ptr) : _ptr(ptr)
@@ -88,7 +90,7 @@ public:
   { return T::count(_ptr); }
 
   bool valid(void) const
-  { return _ptr != NULL; }
+  { return _ptr != (T*)0; }
 
   void clear()
   { put(); }
@@ -104,7 +106,7 @@ private:
   void get(const T* p) const
   { T::get(p); }
   void put(void)
-  { if (!T::put(_ptr)) { delete _ptr; _ptr = 0; } }
+  { if (!T::put(_ptr)) delete _ptr; _ptr = 0; }
   
   // The reference itself.
   T* _ptr;
@@ -121,4 +123,51 @@ T* get_pointer(SGSharedPtr<T> const & p)
 {
   return p.ptr();
 }
+
+/**
+ * static_cast for SGSharedPtr
+ */
+template<class T, class U>
+SGSharedPtr<T> static_pointer_cast(SGSharedPtr<U> const & r)
+{
+  return SGSharedPtr<T>( static_cast<T*>(r.get()) );
+}
+
+/**
+ * Compare two SGSharedPtr<T> objects for equality.
+ *
+ * @note Only pointer values are compared, not the actual objects they are
+ *       pointing at.
+ */
+template<class T, class U>
+bool operator==(const SGSharedPtr<T>& lhs, const SGSharedPtr<U>& rhs)
+{
+  return lhs.get() == rhs.get();
+}
+
+/**
+ * Compare two SGSharedPtr<T> objects for equality.
+ *
+ * @note Only pointer values are compared, not the actual objects they are
+ *       pointing at.
+ */
+template<class T, class U>
+bool operator!=(const SGSharedPtr<T>& lhs, const SGSharedPtr<U>& rhs)
+{
+  return lhs.get() != rhs.get();
+}
+
+/**
+ * Compare two SGSharedPtr<T> objects for weak ordering.
+ *
+ * @note Only pointer values are compared, not the actual objects they are
+ *       pointing at.
+ * @note This allows using SGSharedPtr as key in associative containers like for
+ *       example std::map and std::set.
+ */
+template<class T, class U>
+bool operator<(const SGSharedPtr<T>& lhs, const SGSharedPtr<U>& rhs)
+{
+  return lhs.get() < rhs.get();
+}
 #endif