[PATCH] Rename DynTypedNode to ASTNode

Manuel Klimek klimek at google.com
Wed May 28 00:29:14 PDT 2014 

On Wed, May 28, 2014 at 12:19 AM, Richard Smith <richard at metafoo.co.uk>wrote:

> This type is a union of:
>
>  - Stmt
>  - Decl
>  - Type
>  - TemplateArgument
>  - NestedNameSpecifier
>  - NestedNameSpecifierLoc (!)
>  - QualType (!)
>  - TypeLoc (!)
>  - CXXCtorInitializer
>
> ... and is used for:
>
>  - AST matchers
>  - the parent map (as an implementation detail, where it's really just
> used as an obscure way of writing PointerUnion<Decl*,Stmt*>)
>  - and nothing else
>
> This really seems to be a discriminated union of "the things that AST
> matchers want to match", rather than some fundamental concept like an "AST
> node". So, I'd suggest...
>

>From the AST matchers side "the things that AST matchers want to match" is
by definition "all AST nodes".
(AST matchers also have "attribute matchers" (hasName, etc), but those
always operate on a node).

Since you put (!) behind some of them, let me try to explain why I think
those are AST nodes. I'd roughly describe an AST node as "a part of the AST
that has attributes, or connects other AST nodes". Thus, the "Loc"s are in
there because there is no entity of which a TypeLoc is a mere attribute (a
TypeLoc is more like a type at a location than a location of a type in that
way). Same for QualType, which is more a type with qualifiers than the
qualifiers of a type (here the name matches that concept).


> 1) The parent map stops using it and uses a more appropriate data
> structure (unless we have some reason to think this is the right long-term
> direction for it?)
>

Since generally I think we want to get parents of TypeLocs and the like
(because they for a tree that is not accessible in any other way), I'd
guess that either
a) you have a good different idea on how to make a non-statically-typed
getParents implementation (in which case I agree with you)
b) splitting it out would lead to a lot of duplication


> 2) We move it into ASTMatchers/ as clang::ast_matchers::Node or similar.
>
> Likewise, I think RecursiveASTVisitor should have its own discriminated
> union type, rather than trying to cram its requirements into DynTypedNode.
>

Why? I think DynTypedNode has a pretty good match for everything that tries
to traverse the AST in a non-statically-typed way, as that is kind of what
it was made for.

Cheers,
/Manuel


> On Tue, May 20, 2014 at 11:06 AM, Manuel Klimek <klimek at google.com> wrote:
>
>> +doug & richard, as the keepers of clang
>>
>> I'm not too bought into any name, but somebody needs to make a decision.
>>
>>
>> On Tue, May 20, 2014 at 8:00 PM, Sean Silva <chisophugis at gmail.com>wrote:
>>
>>>
>>>
>>>
>>> On Tue, May 20, 2014 at 11:50 AM, Alp Toker <alp at nuanti.com> wrote:
>>>
>>>>
>>>> On 20/05/2014 20:42, Sean Silva wrote:
>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Tue, May 20, 2014 at 11:37 AM, Alp Toker <alp at nuanti.com <mailto:
>>>>> alp at nuanti.com>> wrote:
>>>>>
>>>>>
>>>>>     On 20/05/2014 20:34, Manuel Klimek wrote:
>>>>>
>>>>>         On Tue, May 20, 2014 at 7:19 PM, Sean Silva
>>>>>         <chisophugis at gmail.com <mailto:chisophugis at gmail.com>
>>>>>         <mailto:chisophugis at gmail.com <mailto:chisophugis at gmail.com>>>
>>>>>
>>>>>         wrote:
>>>>>
>>>>>             Manuel, do you remember why this name was chosen? I seem
>>>>>         to recall
>>>>>             thinking that the name was well-chosen.
>>>>>
>>>>>
>>>>>         It's a DynTypedNode, because the type information is kept /
>>>>>         available dynamically. ASTNode would suggest that there is a
>>>>>         common interface for AST nodes, which there is not.
>>>>>
>>>>>
>>>>>     Well, QualType is a wrapper around Type structures that works
>>>>>     similarly and we don't make the distinction there.
>>>>>
>>>>>
>>>>>         What doesn't work for me is saying "DynTypedNode is an AST
>>>>>         node". This feels wrong. DynTypedNode is more like a "smart
>>>>>         reference".
>>>>>
>>>>>
>>>>>     How about ASTNodeRef? I don't have a strong feeling about ASTNode
>>>>>     / ASTNodeRef or something along those lines, but DynTypedNode
>>>>>     specifically doesn't feel right.
>>>>>
>>>>>     The current name doesn't mean much outside ASTMatchers lingo
>>>>>     whereas the functionality is fairly general and could be useful
>>>>>     elsewhere.
>>>>>
>>>>>
>>>>> There was some speculation about extending use of DynTypedNode outside
>>>>> the ASTMatchers library http://reviews.llvm.org/D33?id=85#inline-386;
>>>>> is there something in particular that you have in mind that you are trying
>>>>> to work towards?
>>>>>
>>>>
>>>> Yes, it became apparent during the RecursiveASTVisitor /
>>>> DataRecursiveASTVisitor that we have two data recursion techniques and this
>>>> showed up as a possible way forward while investigating whether it's
>>>> feasible to unify them. That kind of unification would be far off but the
>>>> associated cleanup makes sense to make this class more discoverable outside
>>>> of ASTMatchers.
>>>>
>>>> DynTypedNode, along with the parent map in ASTContext is fairly useful
>>>> with the caveat that the code reads rather silly with the name
>>>> "DynTypedNode" where what you have and what you want is an AST node
>>>> reference.
>>>>
>>>
>>> Makes sense; I agree that DynTypedNode doesn't work too well in that
>>> context.
>>>
>>> I'm still not a fan of anything that would suggest that there is a
>>> unified AST hierarchy (IMO even ASTNodeRef suggests that there is some sort
>>> of underlying unified "ASTNode" being "Ref"erenced). Maybe ASTVariant?
>>>
>>> -- Sean Silva
>>>
>>>
>>>>
>>>> Alp.
>>>>
>>>>
>>>>
>>>>> -- Sean Silva
>>>>>
>>>>>
>>>>>     Alp.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>         Cheers,
>>>>>         /Manuel
>>>>>
>>>>>
>>>>>             -- Sean Silva
>>>>>
>>>>>
>>>>>             On Sun, May 18, 2014 at 11:18 PM, Alp Toker
>>>>>         <alp at nuanti.com <mailto:alp at nuanti.com>
>>>>>             <mailto:alp at nuanti.com <mailto:alp at nuanti.com>>> wrote:
>>>>>
>>>>>                 This is always referred to as an AST node in
>>>>>         documentation. By
>>>>>                 wrapping Decls, Stmts and QualTypes it provides a
>>>>>         generalised
>>>>>                 way to reference AST nodes. And despite the name,
>>>>>         DynTypedNode
>>>>>                 doesn't have anything to do with dynamic types in the
>>>>> AST.
>>>>>
>>>>>                 The attached patch renames the class and
>>>>> implementation to
>>>>>                 ASTNode.
>>>>>
>>>>>                 (Indeed the namespace "ast_type_traits" is equally
>>>>>         confusing.
>>>>>                 Presumably both are cases where implementation details
>>>>>         have
>>>>>                 leaked into the naming scheme?)
>>>>>
>>>>>                 Alp.
>>>>>
>>>>>                 -- http://www.nuanti.com
>>>>>                 the browser experts
>>>>>
>>>>>
>>>>>                 _______________________________________________
>>>>>                 cfe-commits mailing list
>>>>>         cfe-commits at cs.uiuc.edu <mailto:cfe-commits at cs.uiuc.edu>
>>>>>         <mailto:cfe-commits at cs.uiuc.edu <mailto:cfe-commits at cs.uiuc.
>>>>> edu>>
>>>>>
>>>>>         http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>     --     http://www.nuanti.com
>>>>>     the browser experts
>>>>>
>>>>>
>>>>>
>>>> --
>>>> http://www.nuanti.com
>>>> the browser experts
>>>>
>>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20140528/4954eb48/attachment.html>

More information about the cfe-commits mailing list