Re: [Boost-users] [Spirit] simplified struct.cpp coredumps

Subject: Re: [Boost-users] [Spirit] simplified struct.cpp coredumps
From: philip tucker (phhht_at_[hidden])
Date: 2010-04-04 00:33:46

Thanks, I'll check that out as soon as I grok it and get back to you.

On 3 Apr 2010, at 7:42 PM, OvermindDL1 wrote:

> On Sat, Apr 3, 2010 at 9:40 PM, philip tucker <phhht_at_[hidden]>  
> wrote:
>
>> Hello,
>>
>> I have a Spirit program that fails with a segmentation fault and I  
>> can't see
>> why.  I hope you can help.
>>
>> I'm starting from a simplified version of struct.cpp, known to  
>> work.  I want
>> to abstract the identifier grammar into its own struct and use  
>> that instead
>> of the inline grammar for an identifier.  The problem code is  
>> attached.
>>
>> What have I done wrong?
>>
>> Thanks as always for your patient, expert, and helpful comments.
>>
>> P.S.
>>
>> I'm running boost_1_42_0 with
>>
>> gcc -v:
>> Using built-in specs.
>> Target: i686-apple-darwin9
>> Configured with: /var/tmp/gcc_42/gcc_42-5574~1/src/configure
>> --disable-checking --enable-werror --prefix=/usr --mandir=/usr/ 
>> share/man
>> --enable-languages=c,objc,c++,obj-c++
>> --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/ 
>> usr/lib
>> --build=i686-apple-darwin9 --with-gxx-include-dir=/usr/include/c++/ 
>> 4.0.0
>> --host=i686-apple-darwin9 --target=i686-apple-darwin9
>> Thread model: posix
>> gcc version 4.2.1 (Apple Inc. build 5574)
>>
>> on
>>
>> Model Name: iMac
>> Model Identifier:   iMac9,1
>> Processor Name: Intel Core 2 Duo
>> Processor Speed:    2.66 GHz
>> Number Of Processors:   1
>> Total Number Of Cores:  2
>> L2 Cache:   6 MB
>> Memory: 2 GB
>> Bus Speed:  1.07 GHz
>> Boot ROM Version:   IM91.008D.B08
>> SMC Version (system):   1.44f0
>>
>> P.S.S
>>
>> If you want the coredump, let me know.
>>
>
> I cannot run it right now, not at home, but first of all, you can
> change the id grammar to this (will run and compile faster):
>
>     template <typename Iterator>
>     struct id_grammar : qi::grammar<Iterator, std::string()>
>     {
>         id_grammar() : id_grammar::base_type(start)
>     {
>             using qi::int_;
>             using qi::raw;
>             using ascii::alpha;
>             using ascii::alnum;
>             start %= raw[('_' | alpha) >> *(alnum | '_' | '-')];
>     }
>         qi::rule<Iterator, std::string()> start;
>     };
>
> The thing that is probably causing your failure is that you id grammar
> instance is being destroyed when your main grammar constructor exits
> on this line:
>         client::id_grammar<Iterator> id;
>
> You need to change your whole main grammar to:
>
>     template <typename Iterator>
>     struct employee_grammar : qi::grammar<Iterator,employee 
> (),ascii::space_type>
>     {
>         employee_grammar() : employee_grammar::base_type(start)
>         {
>             using qi::int_;
>             using qi::double_;
>             using qi::lexeme;
>             using ascii::alpha;
>             using ascii::alnum;
>
>             start %=
>                     int_
>
>>>  id
>>>  id
>>>  double_
>>>
>                 ;
>         }
>
>         /*******************************************************/
>         qi::rule<Iterator, std::string(), ascii::space_type> id;
>         /*******************************************************/
>         qi::rule<Iterator, employee(), ascii::space_type> start;
>         client::id_grammar<Iterator> id;
>     };
>
> Does that work?
>
> Remember, if you are creating a grammar/rule, it needs to stick around
> for the whole parse, just like you stuff your rule into start (a class
> data member), you need your grammar a class data member too that you
> use in your rule.  (There are ways to work around that with smart
> pointers and other nasty things, but it is completely unnecessary and
> slower, ignore them, do it the above way.)
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