Added ExceptionPolicy enum.

git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@1082 7ec92016-0320-0410-acc4-a06ded1c099a

include/loki/ScopeGuard.h

@@ -17,6 +17,7 @@
 
 // $Id$
 
+#include <exception>  // needed for calls to uncaught_exception.
 
 #include <loki/RefToValue.h>
 
@@ -42,6 +43,30 @@ namespace Loki
 
     class ScopeGuardImplBase
     {
+
+    public:
+
+        enum ExceptionPolicy
+        {
+            AlwaysExecute     = 0,
+            CallIfNoException = 1,
+            CallIfException   = 2
+        };
+
+        ScopeGuardImplBase() throw() : dismissed_(false), exceptionPolicy_( AlwaysExecute )
+        {}
+
+        void Dismiss() const throw()
+        {
+            dismissed_ = true;
+        }
+
+        void SetExceptionPolicy( ExceptionPolicy policy ) const throw()
+        {
+            exceptionPolicy_ = policy;
+        }
+
+    private:
         /// Copy-assignment operator is not implemented and private.
         ScopeGuardImplBase& operator =(const ScopeGuardImplBase&);
 
@@ -53,6 +78,7 @@ namespace Loki
         /// Copy-constructor takes over responsibility from other ScopeGuard.
         ScopeGuardImplBase(const ScopeGuardImplBase& other) throw()
             : dismissed_(other.dismissed_)
+             , exceptionPolicy_( other.exceptionPolicy_ )
         {
             other.Dismiss();
         }
@@ -60,7 +86,21 @@ namespace Loki
         template <typename J>
         static void SafeExecute(J& j) throw()
         {
+            if ( AlwaysExecute != j.exceptionPolicy_ )
+            {
+                const bool anyThrown = ::std::uncaught_exception();
+                if ( anyThrown )
+                {
+                    if ( CallIfNoException == j.exceptionPolicy_ )
+                        j.Dismiss();
+                }
+                else if ( CallIfException == j.exceptionPolicy_ )
+                {
+                        j.Dismiss();
+                }
+            }
             if (!j.dismissed_)
+            {
                 try
                 {
                     j.Execute();
@@ -68,17 +108,10 @@ namespace Loki
                 catch(...)
                 {}
             }
+        }
 
         mutable bool dismissed_;
-
+        mutable ExceptionPolicy exceptionPolicy_;
-    public:
-        ScopeGuardImplBase() throw() : dismissed_(false) 
-        {}
-
-        void Dismiss() const throw() 
-        {
-            dismissed_ = true;
-        }
     };
 
     ////////////////////////////////////////////////////////////////