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Re: [cdt-dev] Extending GCC parser
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On 7 Apr 2009, at 17:05, Mike Kucera wrote:
Hi Alex,
I'm curious to know why you have chosen to extend the DOM parser
instead of the LR parser. The LR parser is new but it was designed
specifically to be easily extended to add support for new C-based
languages like ObjectiveC. If you have run into problems or concerns
with the LR parser I would like to know what they are.
Plus with the LR parser all the API you need to create the parser is
public (although all the API is "provisional" meaning we can change
it anytime if needed).
Hi Mike,
I'm still finding (stumbling?) my way through CDT at the moment, and
I'm still confused by the array of parsers (for different variants of
C, like C99 and GNUC and .... not to mention the whole DOM vs LR
issue :-)
I spent a bit of time at EclipseCon talking with Markus Schorn about
the Objective C support, and how the whole CDT was put together. In
the course of a quick run-through of how it fits together, we stepped
through the DOM parser and thought that e.g. the parseDeclaration and
expression() would be good injection points for the Objective-C
syntax. As it happens, I've got a bit of code that detects Objective-C
calls in a C expression now, although it constructs a placeholder
ASTNode rather than anything specific at the moment.
I'm not sure how to get started with the LRParser or how to extend it.
The RuleAction code looks like it's being automatically generated from
something, but I don't know where the rule number or rules are being
defined. I also don't have a grammar for objective c files :-) In
fact, I don't think there is a standard grammar - it's mostly defined
by its implementation.
So, if you have any pointers on how to get started with the LR parser
then I could take a look; but the reason I've not run into problems is
I can't find the starting line :-)
Alex
