[cfe-commits] [PATCH] ObjC: interface decls pointing to implementation decls

[steve naroff]

On Jul 20, 2009, at 2:18 PM, Argyrios Kyrtzidis wrote:

>
> On Jul 20, 2009, at 5:50 AM, steve naroff wrote:
>
>> Hey Argyrios,
>>
>> I really like the idea of moving this association from Sema- 
>> >ASTContext.
>>
>> From my perspective, adding getImplementation to the  
>> ObjCContainerDecl AST has the following drawbacks:
>>
>> - The ObjCImplDecl is rarely used. For example Cocoa.h contains  
>> ~700 "containers" that don't have implementations (which include  
>> classes, categories, and protocols). Even for non-system classes/ 
>> categories/protocols, the slot would be rarely used as well (since  
>> most ObjC files/modules contain a very small number of  
>> implementations...1 is very common).
>> - The ObjCImplDecl doesn't make sense for protocols (since they  
>> don't have an implementation).
>>
>> Did you consider adding the following API to ASTContext?
>>
>> For example...
>>
>> ObjCImplementationDecl  
>> *ASTContext::getImplementation(ObjCInterfaceDecl *);
>> ObjCCategoryImplDecl  
>> *ASTContext::getImplementation(ObjCCategoryDecl *);
>>
>> ASTContext would use a "Map" to associate the ObjCContainerDecl  
>> with it's ObjCImplDecl.
>
> Hey great idea!
>
> Please see attached patch.
>

Looks great. I really like the following "convenience" functions:

+ObjCImplementationDecl *ObjCInterfaceDecl::getImplementation() const {
+  return getASTContext().getObjCImplementation(
+                                           
const_cast<ObjCInterfaceDecl*>(this));
+}
+
+void ObjCInterfaceDecl::setImplementation(ObjCImplementationDecl  
*ImplD) {
+  getASTContext().setObjCImplementation(this, ImplD);
+}
+

Now that every Decl can get a pointer to it's ASTContext (something  
Chris reminded me of earlier today), I bet there are other interesting  
space optimizations that we can make to decls (*without* complicating  
the API:-). For example, *every* ParmVarDecl currently has a  
DefaultArg slot (that is only available for C++). Cocoa.h has 30,000  
ParmVarDecl's! Might be interesting to consider using an ASTContext  
Map to store these as well.

snaroff

> -Argiris
>
> <objc_impl.patch>
>
>