[PATCH] Store paren locations in IfStmt, WhileStmt, SwitchStmt.

[Eli Bendersky]

On Wed, Oct 1, 2014 at 3:12 PM, Alexander Kornienko <alexfh at google.com>
wrote:

> >>! In D5528#5, @doug.gregor wrote:
> > In non-macro cases, one can extract the locations of the parentheses
> using the lexer. Personally, I don't think the benefits of being able to
> extract the locations of the parentheses efficiently or in the macro cases
> outweigh the disadvantages of bloating the AST further.
>
> For the context: this patch resulted from the discussion on D5395.
>
> I understand your concerns about bloating the AST. Some locations can be
> relatively easy found by re-lexing small parts of the input. One problem
> with this approach is that everyone who needs these locations spends time
> looking for a way to get them and then writing their own implementation. Is
> there a document or a comment describing the high-level approach to what is
> considered worthy storing in the AST?
>
> Also, it may be reasonable to add utility methods in the AST classes (or
> free-standing functions in clang/AST headers) for retrieving some less
> frequently used locations of syntactic constructs in non-macro cases (e.g.
> WhileStmt::findRParenLoc() which would find the first non-comment token
> after getCond()->getLocEnd()). What do you think?
>

FWIW, we ran into exactly the same need, and developed a bunch of utility
methods that use the lexer to grab the next token, find matching tokens
after some location, etc. Having these available somewhere in Clang would
be definitely useful.

Eli
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