Feature/as refactor review (#821)

* Replace dynamicCast with as where does not change behavior (ie not Type derived).
Use free function where scoping is clear.

* Replace uses of dynamicCast with as when there is no difference in behavior.

* Remove the IsXXXX methods from Type.

* Don't have separate smart pointer to store canonicalType on Type.

* Simplify Slang.FilteredMemberRefList.Adjust, such does the cast directly.

* Use free as where appropriate.

* Use free function version of casts where appropriate.

* Fix text in casting.md

* Fix typos in decl-refs.md

* Remove the uses of free function as on RefDecl.
Add 'canAs' to RefDecl as a way to test if a cast is possible.
Moved 'as' into RefDeclBase.

* Use 'is' to test for as cast on smart pointers.
Fix small scope issue.

* * Cache stringType and enumTypeType on the Session
* Make DeclRefType::Create return a RefPtr
* Make casting of result use the *method* .as  (cos using free function would mean objects being wrongly destroyed)
* Make results from createInstance ref'd to avoid possible leaks.

* Fix typo in template parameter for is on RefPtr.

1 files changed, 3 insertions, 0 deletions

diff --git a/source/core/smart-pointer.h b/source/core/smart-pointer.h
index d026388c0..e19ed6a4d 100644
--- a/source/core/smart-pointer.h
+++ b/source/core/smart-pointer.h
@@ -194,6 +194,9 @@ namespace Slang
             return RefPtr<U>(Slang::as<U>(pointer));
         }
 
+        template <typename U>
+        bool is() const { return Slang::as<U>(pointer) != nullptr; }
+
         ~RefPtr()
         {
             releaseReference((Slang::RefObject*) pointer);