[cfe-dev] implementing clone for ASTNodes

[Aleksei Sidorin via cfe-dev]

Hello Gaetano,

ASTImporter not just "imports" AST nodes. It also searches if they 
already exist in the destination AST. It is required to get a consistent 
AST.

I was thinking about "clone" approach some time ago, but the question 
how to handle complex dependencies is still open here.



18.01.2017 19:55, Gaetano Checinski via cfe-dev пишет:
> I was wondering if anybody spend some efforts in implementing a clone 
> Method for all ASTNodes?
>
> It seems to me, that the current approach implemented in the 
> ASTImporter is error-prone and hard to maintain.
>
> Currently it looks to me that Decls / Stmt's are being probed for 
> their type and then downcasted, eg.:
>
>     /* ASTNodeImporter::VisitExplicitCastExpr */
>     /* ASTImporter.cpp:6060 */
>     switch (E->getStmtClass()) {
>       case Stmt::CStyleCastExprClass: {
>          CStyleCastExpr *CCE = cast<CStyleCastExpr>(E);
>          return CStyleCastExpr::Create(Importer.getToContext(), T,
>     E->getValueKind(), E->getCastKind(),
>             SubExpr, &BasePath, TInfo,
>     Importer.Import(CCE->getLParenLoc()),
>     Importer.Import(CCE->getRParenLoc()));
>     }
>     /* more cases*/
>
>
>
> As the AST contains circular references and many nodes require an 
> ASTContext
> for construction, i'm wondering how feasible it would be to implement 
> the following interface for each Decl?
>
>      virtual Decl* clone(
>        ASTContext* newContext,
>        DenseMap<Decl*, Decl*> ImportedDeclsCache = {}
>      );
>
>
>
>
>
>
>
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-- 
Best regards,
Aleksei Sidorin,
SRR, Samsung Electronics

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