Re: Qi Symbols mapping to AST enum

On Wed, Nov 28, 2018 at 7:37 PM Henri Menke <[email protected]> wrote:
>
>
>
> On 29/11/18 12:35 PM, Michael Powell wrote:
> > Hello,
> >
> > I've got a qi::symbols capturing some built-in types. At the moment, I
> > gather, they are mapped to std::string. However, I would rather map
> > them to an AST level enum.
> >
> > For instance,
> >
> > struct builtin_type_t : qi::symbols<char, std::string> {
> >     builtin_type_t() {
> >         this->add("double", "double")
> >             ("float", "float")
> >             // ...
> >             ;
> >     }
> > } builtin_type;
> >
> > Instead,
> >
> > namespace ast {
> >     enum type_t { type_double, type_float /* , ... */ };
> > }
> >
> > struct builtin_type_t : qi::symbols<char, ast::type_t> {
> >     builtin_type_t() {
> >         this->add("double", ast::type_double)
> >             ("float", ast::type_float)
> >             // ...
> >             ;
> >     }
> > } builtin_type;
>
> Yes, this is entirely possible.  Below is a minimal example.  Just an
> aside, you shouldn't name types with `_t` in the end because those are
> names reserved for POSIX, see
> https://www.gnu.org/software/libc/manual/html_node/Reserved-Names.html

Well, at the moment I am not concerned with either posix or C, but
this is good to know, thanks for raising my awareness.

The feedback is appreciated, thanks.

> #include <boost/spirit/include/qi.hpp>
> #include <iostream>
>
> namespace qi = boost::spirit::qi;
>
> namespace ast {
> enum type_t { type_double, type_float /* , ... */ };
> }
>
> struct builtin_type_t : qi::symbols<char, ast::type_t> {
>     builtin_type_t() {
>         this->add
>             ("double", ast::type_double)
>             ("float", ast::type_float)
>             // ...
>             ;
>     }
> } builtin_type;
>
> int main() {
>     std::string input = "float";
>     std::string::iterator iter = input.begin();
>     std::string::iterator end = input.end();
>
>     ast::type_t result;
>     bool r = parse(iter, end, builtin_type, result);
>     if (!r || iter != end) {
>         std::cerr << "Parsing failed at: " << std::string(iter, end)
>                   << "\n";
>         return 1;
>     }
>
>     switch (result) {
>     case ast::type_double:
>         std::cout << "double\n";
>         break;
>     case ast::type_float:
>         std::cout << "float\n";
>         break;
>     default:
>         std::cerr << "Error: Unknown type!\n";
>     }
> }
>
> >
> > I assume this is possible? Am I missing something about that?
> >
> > Thanks!
> >
> > Michael Powell
> >
> >
> > _______________________________________________
> > Spirit-general mailing list
> > [email protected]
> > https://lists.sourceforge.net/lists/listinfo/spirit-general
> >
>
>
>
> _______________________________________________
> Spirit-general mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/spirit-general