Re: Not able to use x3::skip(skipper)[some recursive rule] in its rule definition

Hi Larry,

Thanks. I've tried this get_rhs branch but it doesn't solve this problem.
Still get the same error.

Best regards,
Han

On Tue, Jul 25, 2017 at 1:21 PM, Larry Evans <[email protected]>
wrote:

> On 07/25/2017 03:40 AM, Han Wang wrote:
>
>> I've posted the same question in stackoverflow.
>>
>> https://stackoverflow.com/questions/45282293/spirit-not-able
>> -to-use-x3skipskippersome-recursive-rule-in-its-rule-defin
>>
>> Let's say we want to parse a recursive block like this. When
>> "|skip_comments_tag|" is prefixed to the block, we skip all
>> comments(|/*...*/|) within this block recursively.
>>
>> |{{}{skip_comments_tag{{}/*comments*/{/*comments*/}}}}|
>>
>> It's easy to come up with a recursive parser as in Coliru <
>> http://coliru.stacked-crooked.com/a/31fb17064091fae3>.
>>
>> |namespaceParser{autoconstruleComment =x3::lit("/*")>>*(x3::char_
>> -"*/")>>"*/"|x3::space;x3::rule<structSBlockId>construleBlock;autoconstruleBlock_def
>> =x3::lit('{')>>*(ruleBlock |"skip_comments_tag">>x3::skip
>> (ruleComment)[ruleBlock])>>'}';BOOST_SPIRIT_DEFINE(ruleBlock)}|
>>
>> But it doesn't compile (when the |parse| function is called) because it
>> will generate an infinite context (by |x3::make_context| in
>> |x3::skip_directive|). |x3::no_case| and |x3::with| also have this problem
>> because they all use |x3::make_context| in the implementation.
>>
>> Questions:
>>
>>  1. Is there always a better way to write parsers for this kind of
>>     questions to avoid such compile error and how?
>>  2. Or is the |x3::make_context| implementation considered to be flawed
>>     for this kind of questions?
>>
>> BTW: TU seperation doesn't solve this.
>>
>> Hi Han.
>
> You might try the get_rhs branch of a spirit fork here:
>
> https://github.com/cppljevans/spirit/tree/get_rhs
>
> and then #define BOOST_SPIRIT_GET_RHS_CRTP.  As you can see from here:
>
> https://github.com/cppljevans/spirit/blob/get_rhs/include/bo
> ost/spirit/home/x3/nonterminal/detail/rule.hpp#L140
>
> that will disable the x3::make_context calls.
>
> Please let me know if that works.  If so, I might be
> encouraged enough to go to the trouble of creating a pull request
> despite the need (as pointed out in a private email) that
> I'll need to document the rationale for the pull request.
>
> HTH.
>
> -regards,
> Larry
>
>
>
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