Re: [Boost-users] [spirit] help parsing data file into a struct

Subject: Re: [Boost-users] [spirit] help parsing data file into a struct
From: Kenny Riddile (kfriddile_at_[hidden])
Date: 2009-12-18 09:55:41

OvermindDL1 wrote:
> On Thu, Dec 17, 2009 at 11:44 AM, Kenny Riddile <kfriddile_at_[hidden]> wrote:
>> This is my first time using Spirit and I haven't messed with writing EBNF
>> grammars since college, so I'm sorry if this is a simple question.  Lets say
>> I have a structure that looks like this:
>>
>> struct Foo
>> {
>>    std::string someString;
>>    std::string someOtherString;
>>    std::vector<std::string> stringList;
>> };
>>
>> BOOST_FUSION_ADAPT_STRUCT(
>>    Foo,
>>    (std::string, someString)
>>    (std::string, someOtherString)
>>    (std::vector<std::string>, stringList) )
>>
>> and I have a data file that looks like this:
>>
>> SOMESTRING hello
>> SOMEOTHERSTRING goodbye
>>
>> STRINGLIST
>> {
>>    string1
>>    string2
>>    string3
>> }
>>
>> I have written the following grammar to parse such a file into the struct
>> above:
>>
>> template< typename Iterator >
>> struct FooDefinition : spirit::qi::grammar< Iterator, Foo() >
>> {
>>    FooDefinition()
>>        : FooDefinition::base_type( start )
>>    {
>>        using namespace spirit::qi;
>>
>>        start = someString >> +space >> someOtherString >> +space >>
>> stringList;
>>        someString = lit("SOMESTRING") >> +space >> value;
>>        someOtherString = lit("SOMEOTHERSTRING") >> +space >> value;
>>        stringList = lit("STRINGLIST") >> *space >> lit('{') >> *space >>
>> (value % +space) >> *space >> lit('}');
>>        value = +char_("a-zA-Z_0-9");
>>        space = lit(' ') | lit('\n') | lit('\t');
>>    }
>>
>>    spirit::qi::rule< Iterator, Foo() > start;
>>    spirit::qi::rule< Iterator, std::string() > someString;
>>    spirit::qi::rule< Iterator, std::string() > someOtherString;
>>    spirit::qi::rule< Iterator, std::vector<std::string>() > stringList;
>>    spirit::qi::rule< Iterator, std::string() > value;
>>    spirit::qi::rule< Iterator > space;
>> };
>>
>> However, I would like the order of the three statements in the data file
>> (SOMESTRING, SOMEOTHERSTRING, and STRINGLIST) to be irrelevant.  Right now,
>> they must be in the order shown above for parsing to succeed.  How would I
>> go about accomplishing this with Spirit?
> 
> That is what the permutation operator is for ( ^ ), and it acts like,
> well, a permutation.  :)
> 
> This is also answered faster if asked on the Spirit mailing list.
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> Boost-users mailing list
> Boost-users_at_[hidden]
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Sigh...thanks, that works beautifully.  I figured it was something 
simple I used to know and had forgotten.