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Re: [cdt-dev] How to extend the C99 / GCC LR Parser

Hi Markus and Mike,

I understood that I could make a request to extend the internal parser to support this type of variable definitions.
Of course I don't have a very good overview, but my feeling is that the LR parser is a bit more flexible. Is it correct that I could implement the extension for this variable definition without waiting for a fix of the CDT core when I use the LR parser?

Mike, could you give me just the basic steps how you would implement the extension using the LR parser to just accept the @ <address> after a variable definition? Which functions/ modules do I need to modify?


Thanks in advance


Sebastian




-----Ursprüngliche Nachricht-----
Von: "Schorn, Markus" <Markus.Schorn@xxxxxxxxxxxxx>
Gesendet: Jul 11, 2011 11:01:54 AM
An: "CDT General developers list." <cdt-dev@xxxxxxxxxxx>
Betreff: Re: [cdt-dev] How to extend the C99 / GCC LR Parser

>Hi Sebastian,
>You need an additional parser extension, you can ask for it via bugzilla. Please add a specification of the extension, ideally you can point to a document in the Web.
>We have added support for similar custom extensions in the past, see ICParserExtensionConfiguration.
>Markus.
>
>-----Original Message-----
>From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Sebastian Wagner
>Sent: Monday, July 11, 2011 10:43
>To: CDT General developers list.
>Subject: Re: [cdt-dev] How to extend the C99 / GCC LR Parser
>Importance: Low
>
>Hi Markus,
>
>first thanks for your proposal. Your are right,  I also have the feeling that in my case this would be much easier, even if I also would like to understand the parsers a bit better.
>
>In implementation I simply added macros to replace the new keywords by an empty space. This worked so far and was not perfect but acceptable. My problem is the following extension to the variable definitions, which is used for register defintions in the microcontroller and sometimes for variables :
>
>volatile short int PORT_A @ 0x0100;
>
>While it is simple to replace fixed keywords I didn't know how to manage the @ and the memory address after the definition. Do you have any idea how I could solve this?
>
>
>best regards
>
>Sebastian
>
>
>-----Ursprüngliche Nachricht-----
>Von: "Schorn, Markus" <Markus.Schorn@xxxxxxxxxxxxx>
>Gesendet: Jul 8, 2011 8:22:15 AM
>An: "CDT General developers list." <cdt-dev@xxxxxxxxxxx>
>Betreff: Re: [cdt-dev] How to extend the C99 / GCC LR Parser
>
>>Hi Sebastian,
>>While extending the parser is a valid option, it will be much easier, if you manage to configure the existing parser.
>>Clearly, it is not possible to handle every language extension in that way, but it may work in your case.
>>For instance, depending on what __data16 does, I would try to map it to either 'short' or to the empty token.
>>
>>To configure the existing parser you need to subclass GCCLanguage and provide a customized IScannerExtensionConfiguration and/or ICParserExtensionConfiguration.
>>
>>Markus.
>>
>>-----Original Message-----
>>From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx]
>>On Behalf Of Sebastian Wagner
>>Sent: Thursday, July 07, 2011 17:11
>>To: cdt-dev@xxxxxxxxxxx
>>Subject: [cdt-dev] How to extend the C99 / GCC LR Parser
>>Importance: Low
>>
>>Hello all,
>>
>>I am working on a parser for a C based language which contains some small extensions, e.g. special type qualifiers. Therefore I would like to extend the C99 or GCC LR Parser.
>>
>>I read a lot of content in the web and CDT source code. I managed to generate the Parser from the grammar file and I'm able to compile the generated files. I also understood that today the lexer is not generated using the LPG, but is a part of the preprocessor.
>>
>>Now, nevertheless I didn't get the complete overview where I need to do changes if for instance I want to add a new type qualifier "__data16". Do I have to do modifications on the preprocessor and do I do that? I think keywords can be added using the ScannerExtensionConfiguration, but I don't know how to do this correctly. Do I also need to do adaptations to the AST?
>>
>>It would be great if one of you could give me a short overview in which modules I need to do modifications, so that I understand the behavior better.
>>
>>Thanks in advance!!
>>
>>
>>Sebastian Wagner
>>
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