[cfe-dev] Proposal to simplify ObjC Type AST's

[Chris Hanson]

On May 19, 2009, at 11:22 AM, steve naroff wrote:

> // Seven classes. In this case, ObjCObjectPointerType is abstract.
>
> class ObjCObjectPointerType : public Type { ... };
>
> class ObjCIdType : public ObjCObjectPointerType { ... };
> class ObjCInterfacePointerType : public ObjCObjectPointerType { ... };
> class ObjCClassType : public ObjCObjectPointerType { ... };
>
> class ObjCQualifiedIdType : public ObjCIdType, public  
> llvm::FoldingSetNode { ... };
> class ObjCQualifiedInterfacePointerType : public  
> ObjCInterfacePointerType, public llvm::FoldingSetNode { ... };
> class ObjCQualifiedClassType : public ObjCClassType, public  
> llvm::FoldingSetNode { ... };
>
> I think having a common base class (abstract or not) makes either of  
> these more appealing than what we have now.

How about eight classes?

// Eight classes. In this case, both ObJCObjectPointerType and  
ObjCProtocolQualifierNode are abstract.

class ObjCObjectPointerType : public Type { ... };

class ObjCIdType : public ObjCObjectPointerType { ... };
class ObjCInterfacePointerType : public ObjCObjectPointerType { ... };
class ObjCClassType : public ObjCObjectPointerType { ... };

class ObjCProtocolQualifierNode : public llvm::FoldingSetNode { ... };

class ObjCQualifiedIdtype : public ObjCIdType, public  
ObjCProtocolQualifierNode { ... };
class ObjCQualifiedInterfacePointerType : public  
ObjCInterfacePointerType, public ObjCProtocolQualifierNode { ... };
class ObjCQualifiedClassType : public ObjCClassType, public  
ObjCProtocolQualifierNode { ... };

This composition enables the "protocol-qualified" concept to be  
abstract too.

(I don't know the clang codebase enough to give  
ObJCProtocolQualifierNode a good name.)

   -- Chris

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