Re: [Boost-users] [Spirit] Creating a vector of structs

Subject: Re: [Boost-users] [Spirit] Creating a vector of structs
From: Lindley M French (lfrench1_at_[hidden])
Date: 2009-09-01 21:31:01

> On Tue, Sep 1, 2009 at 4:38 PM, Lindley M French<lfrench1_at_[hidden]> 
> wrote:> I'm playing around with Spirit for a particular parsing 
> task. I could do this manually, but I figured this was a good 
> chance to learn what Spirit had to offer.
> >
> > The trouble is this. While Spirit offers ready-made semantic 
> actions for parsing primitives, it doesn't seem to offer anything 
> terribly useful for compound statements. As far as I can tell, you 
> can define your own semantic actions but they simply take in the 
> matched string as an argument----there's no way to get at the 
> values parsed on that level.
> >
> > For example, let's say I have a type
> > struct Person
> > {
> > ? string name;
> > ? double height;
> > ? int age;
> > ? Person(string n, double h, int a)
> > ? : name(n), height(h), age(a)
> > };
> >
> > And I have a document containing
> >
> > 5.5 15 Henry
> > 4.6 32 Jane
> > 6.1 21 Bob
> >
> > I could parse this using
> >
> > rule<> personrule = strict_real_p >> int_p >> ~eol_p;
> > parse(str, *(personrule[WhatGoesHere] >> eol_p) >> end_p);
> >
> > But how can I build a vector<Person> out of this? I can write my 
> own functor to do the push_back, but I need to get at the parsed 
> values of name, age, and height for each personrule somehow.
> >
> > I suppose I *could* just run another parse() on the input the 
> semantic action for that specific person....but that really seems 
> like it shouldn't be necessary.
> 
> You are using Spirit.Classic, you should use Spirit.QI (Boost trunk,
> docs are at: 
> http://svn.boost.org/svn/boost/trunk/libs/spirit/doc/html/index.html), then you can do it easy, like so:
> 
> BOOST_FUSION_ADAPT_STRUCT(Person
>                         (double,height)
>                         (int,age)
>                         (string,name)
>                         )
> 
> rule<YourIteratorType> personrule;
> personrule %= double_ >> int_ >> raw[lexeme[*(char_-eol)]];
> std::vector<Person> theVec;
> parse(str.begin(),str.end(), *personrule, theVec);
> 
> This is also better to ask on the spirit mailing list.  :)

Unfortunately for the moment I'm stuck with Boost 1.35, which I don't believe has Spirit 2. I'll try asking on the Spirit list.