[cfe-commits] libclang: Patch to get an integer value from a cursor.

[Argyrios Kyrtzidis]

On Sep 23, 2011, at 7:13 AM, Vinay Sajip wrote:

>> ________________________________
>> From: Argyrios Kyrtzidis <kyrtzidis at apple.com>
>> 
>> Merging unrelated functionality in one function does not seem ideal.
>> 
>> 
>> How about:
>> -actually expose the attributes that you are interested in
>> -adding clang_getConstantValue(CXCursor) where CXCursor can be a decl with an init value (like CXCursor_EnumConstantDecl) or a constant-folded expression.
>> -adding clang_getBitfieldWidth(CXCursor) where CXCursor is a FieldDecl (separate function otherwise there may be some difficulty distinguishing between a bitfield width and an in-class initializer)
> 
> I agree in principle, but I wasn't sure how a widened API (i.e. one with more entry points) would be received. I have at least three values that I need to get out of the AST:
> 
> 1. Enumeration constants.
> 2. Bit field widths.
> 3. Declaration attributes such as calling conventions or inlining directives.
> 
> So, I would think an API such as the following would be appropriate for the first two:
> 
> 
> long long clang_getConstantValue(CXCursor);
> int clang_getBitFieldWidth(CXCursor); // int seems reasonable for a bit field width, do you prefer Bitfield over BitField?

"Bitfield" seems to be the convention in AST, though it's not consistent everywhere.

> 
> For declaration attributes, these are stored as separate unexposed attribute nodes at the moment. So we could add an API
> 
> int clang_getAttributeValue(CXCursor);
> 
> which returns -1 for non-attribute nodes and the appropriate attribute kind for attribute nodes. However, as these values are currently unexposed in the libclang API, they are prone to change and there isn't a mapping between internal values and external values (for example IIRC the AlwaysInline attribute has changed from 8 to 9 since I started working with clang, which is fairly recently). This suggests that a clang_getAttributeKind API is required to map from internal values to an unchanging external set of values such as e.g. CXAttribute_AlwaysInline. I've tried to keep API additions to a minimum as at the moment I'm finding that a lot of time is spent in conflict resolution when rebasing/merging with origin/master. I'm not sure why this is - I'm not as familiar with Git as I am with Mercurial but I'm following what I understand to be best practice.

When I said "expose the attributes" I meant adding the attributes that you are interested in CXCursorKind, see:

  CXCursor_UnexposedAttr                 = 400,

  CXCursor_IBActionAttr                  = 401,
  CXCursor_IBOutletAttr                  = 402,
  CXCursor_IBOutletCollectionAttr        = 403,
  CXCursor_CXXFinalAttr                  = 404,
  CXCursor_CXXOverrideAttr               = 405,
  CXCursor_LastAttr                      = CXCursor_CXXOverrideAttr,

We can add new ones here.


> 
> Your comments on the API suggestions above would be appreciated.
> Regards,
> 
> Vinay Sajip
> 
> 
> _______________________________________________
> cfe-commits mailing list
> cfe-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits