Re: How to escape the hyphen char in set by char parser?

As you noted a range can be written as

   'a' | 'b' | 'c' | 'd' | '-' | '+' | 'x'

Since '-' has a special meaning (and '+' might as well), you could just 
write it as a superposition of

   match any of the set "abcdx"
   OR
   match '-'
   OR
   match '+'

which is in Boost.Spirit syntax

    char_("abcdx") | char_('-') | char_('+');

Below is a full example (using X3 rather than Qi, because of compilation 
time).

#include <iostream>
#include <string>

#include <boost/spirit/home/x3.hpp>

int main() {
     using namespace boost::spirit::x3;

     auto rule = char_("abcdx") | char_('-') | char_('+');

     std::string input{"-"};
     auto first = input.begin();
     auto last = input.end();

     bool r = parse(first, last, rule);

     if (!r || first != last) {
         std::cerr << "Parsing failed at: " << std::string{first,last} 
<< '\n';
     }
}

On 17/07/18 04:37, Yi Leong wrote:
> As following:
> qi::char_("abcd-+x")
> what i need just matches the char 'a' | 'b' | 'c' | 'd' | ‘-’ | ‘+’ | ‘x’,
> and the char parser takes hyphen '-' as the range matching from 'd' to 
> '+'....
> and how to escape the hyphen char?
> I read this doc :
> https://www.boost.org/doc/libs/1_46_0/libs/spirit/doc/html/spirit/qi/reference/char/char.html
> and got nothing....
> 
> 
> 
> ------------------------------------------------------------------------------
> Check out the vibrant tech community on one of the world's most
> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> 
> 
> 
> _______________________________________________
> Spirit-general mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/spirit-general
> 

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Spirit-general mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/spirit-general