Re: [Boost-users] Boost Spirit Karma - convert character to hex representation

Subject: Re: [Boost-users] Boost Spirit Karma - convert character to hex representation
From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2015-04-20 07:57:13

> Padding looks like what the doctor ordered. However I'm concerned with
> upper/lower directives. What is needed in hex is a simple mapping for 6
> letters from a..z to A..Z and vice versa. Upper/lower, I guess, will
> employ std::locale to work properly which in turn uses std::facet which
> (at least in Windows) has lazy initialization and protected by
> CriticalSection. This is a performance killer, I've just spent two weeks
> getting rid of these from my code. Now tell me that I'm wrong and these
> directives do not use std::locale and I will be happy for the rest of my
> life :)

The implementation of upper/lower depends on the used character set. By default those simply map to std::isupper()/std::islower() (see https://github.com/boostorg/spirit/blob/master/include/boost/spirit/home/support/char_encoding/ascii.hpp#L281).

Looks like you can be happy 'till the end of your life!

> Otherwise I would like to know if there is another possibility to control
> hex letter case

There is always the possibility for you to write your own generator (which is not too difficult). See here for some explanation: http://boost-spirit.com/home/articles/karma-examples/creating-your-own-generator-component-for-spirit-karma/.

HTH
Regards Hartmut
---------------
http://boost-spirit.com
http://stellar.cct.lsu.edu

> 
> -----Original Message-----
> From: Boost-users [mailto:boost-users-bounces_at_[hidden]] On Behalf
> Of Hartmut Kaiser
> Sent: Sunday, April 19, 2015 4:23 PM
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] Boost Spirit Karma - convert character to hex
> representation
> 
> 
> > There is karma::hex formatter and I need somehow to add zero padding
> > to get “0a” instead of just “a”. in addition it would be lovely to
> > have some king of control over hex letter case. It sounds like a
> > policies for real or Boolean formatters but I didn’t find one for hex.
> > Is it possible to achieve the above without policy?
> 
> Padding can be achieved by using the right_align[] directive:
> http://www.boost.org/doc/libs/1_58_0/libs/spirit/doc/html/spirit/karma/ref
> erence/directive/alignment.html.
> 
> You can control the hex-letter case using the upper[] and lower[]
> directives:
> http://www.boost.org/doc/libs/1_58_0/libs/spirit/doc/html/spirit/karma/ref
> erence/directive/upperlower.html.
> 
> HTH
> Regards Hartmut
> ---------------
> http://boost-spirit.com
> http://stellar.cct.lsu.edu
> 
> 
> 
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