[cfe-dev] Why Printer Classes are private?

[Roman Popov via cfe-dev]

Unfortunately in addition to Visitors, DeclPrinter also has some hidden
helper printXXX methods:  printTemplateParameters, printTemplateArguments,
etc....
So even if we add PrintHelper to override some visitors, it won't have an
access to those very useful helpers.

This seems to me as a fundamental limitation of curiously recurring
template pattern : unlike real dynamic dispatch, it allows only a single
level of inheritance.

Does anyone have any ideas how to allow customization of a DeclPrinter?

2017-10-19 9:46 GMT-07:00 Alex L <arphaman at gmail.com>:

>
>
> On 18 October 2017 at 17:07, Roman Popov <ripopov at gmail.com> wrote:
>
>> Hi Alex,
>> I can probably look into it if I have time and will feel myself confident
>> enough. I've started learning Clang just recently (and my background is HW
>> design, not programming).
>>
>> Meanwhile I've found a workaround to do what I've needed originally:
>> Instead of printing nodes in a special way, I create Replacements for
>> them, then use a temporary Rewriter to apply replacements and get back text
>> I wanted to print.
>>
>
>> Probably it was supposed to be always done like that?
>>
>
> I think that it's definitely a viable option.
>
>
>>
>> The only problem is the case when I don't have parts of AST in original
>> source code. For example when I deal with template instantiations. In that
>> case I will have to emit implicit template specializations in overlay
>> filesystem, reparse TU again, and then create replacements for nodes of
>> interest.
>>
>
>> So If I had a capability to customize AST pretty-printer, I won't need to
>> re-parse source code multiple times.
>>
>
> Personally I would be interested in adding such a customization to the
> DeclPrinter for some of my work as well. I'm not currently working on, but
> I might get to it in a couple of weeks. However if you think that you would
> benefit from such a customization now, I would recommend you to look into
> providing patches for such customization. If you are interested in learning
> more about contributing to Clang feel free to take a look at the
> documentation that we have:
> http://llvm.org/docs/GettingStarted.html
>
>
>
>>
>>
>>
>> 2017-10-18 16:30 GMT-07:00 Alex L <arphaman at gmail.com>:
>>
>>> Hi Roman,
>>>
>>> On 18 October 2017 at 14:35, Roman Popov via cfe-dev <
>>> cfe-dev at lists.llvm.org> wrote:
>>>
>>>> In StmtPrinter there is a PrintHelper that can be used to override
>>>> printing of some nodes. I guess PrintHelper was introduced for someone
>>>> like me that wanted to override some StmtPrinter visitors.
>>>> But DeclPrinter does not supports PrintHelper for some reason.
>>>>
>>>
>>> It's possible that nobody else needed a customized DeclPrinter
>>> before, so it wasn't necessary to add a helper for it.
>>> I think that it would make sense to add a helper class for DeclPrinter
>>> if there's a good enough justification for it. Would you be interested in
>>> working on a patch for such a helper class?
>>>
>>> Alex
>>>
>>>
>>>
>>>>
>>>>
>>>> 2017-10-18 12:53 GMT-07:00 Roman Popov <ripopov at gmail.com>:
>>>>
>>>>> Hello,
>>>>> I want to redefine some visitors in DeclPrinter and StmtPrinter, but
>>>>> they are not exported over Clang API. Why is that?
>>>>>
>>>>> Currently I have to copy-paste them into my tool. But this
>>>>> unfortunately leads to some duplication.
>>>>>
>>>>> -Roman
>>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> cfe-dev mailing list
>>>> cfe-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>
>>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20171020/ce07e5db/attachment.html>