ENH: Added safe downcast support (without RTTI) to cmCommand and its subclasses.

1 files changed, 37 insertions, 0 deletions

diff --git a/Source/cmCommand.h b/Source/cmCommand.h
index aefd757..55841c4 100644
--- a/Source/cmCommand.h
+++ b/Source/cmCommand.h
@@ -122,6 +122,19 @@ public:
   const char* GetError() 
     {return m_Error.c_str();}
 
+  /**
+   * Returns true if this class is the given class, or a subclass of it.
+   */
+  static bool IsTypeOf(const char *type)
+    { return !strcmp("cmCommand", type); }
+  
+  /**
+   * Returns true if this object is an instance of the given class or
+   * a subclass of it.
+   */
+  virtual bool IsA(const char *type)
+    { return cmCommand::IsTypeOf(type); }
+
 protected:
   void SetError(const char* e)
     {
@@ -136,4 +149,28 @@ private:
   std::string m_Error;
 };
 
+// All subclasses of cmCommand should invoke this macro.
+#define cmTypeMacro(thisClass,superclass) \
+static bool IsTypeOf(const char *type) \
+{ \
+  if ( !strcmp(#thisClass,type) ) \
+    { \
+    return true; \
+    } \
+  return superclass::IsTypeOf(type); \
+} \
+virtual bool IsA(const char *type) \
+{ \
+  return thisClass::IsTypeOf(type); \
+} \
+static thisClass* SafeDownCast(cmCommand *c) \
+{ \
+  if ( c && c->IsA(#thisClass) ) \
+    { \
+    return (thisClass *)c; \
+    } \
+  return 0;\
+}
+
+
 #endif