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

Ok, i will separate the set .

Thanks for help~

On Tue, Jul 17, 2018 at 7:47 AM, Henri Menke <[email protected]> wrote:

> 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....
>>
>>
>>
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