Re: [Boost-users] Using boost string algorithm with BOOST_NO_STD_LOCALE

Subject: Re: [Boost-users] Using boost string algorithm with BOOST_NO_STD_LOCALE
From: Václav Zeman (vhaisman_at_[hidden])
Date: 2012-06-27 01:34:40

On 06/26/2012 08:50 PM, Allan Nielsen wrote:
> Hi,
>
> I'm developing for an embedded environment where we do not have a
> complete c++ standard library available, and one of the things missing
> is std::locale.
>
> But even without this feature, I would very much like to use the boost
> string algorithms ( split, tokenize, etc ). The only problem is that
> they depends on std::locale. I have been looking around in the source
> code, trying to see how easy it would be to add the needed ifdef's to
> make it work without std::locale. Most of the code looks straight
> forward to modify, but I'm stuck on this function:
>
>             struct is_classifiedF :
>                 public predicate_facade<is_classifiedF>
>             {
>                 // Boost.ResultOf support
>                 typedef bool result_type;
>
>                 // Constructor from a locale
>                 is_classifiedF(std::ctype_base::mask Type, std::locale
> const & Loc = std::locale()) :
>                     m_Type(Type), m_Locale(Loc) {}
>                 // Operation
>                 template<typename CharT>
>                 bool operator()( CharT Ch ) const
>                 {
>                     return std::use_facet< std::ctype<CharT>
>> (m_Locale).is( m_Type, Ch );
>                 }
>
>             private:
>                 std::ctype_base::mask m_Type;
>                 std::locale m_Locale;
>             };
>
> I know what the code does, I just do not know how it does it. This is
> without a doubt because I know nothing about locale, facet, etc.
>
> What I would like is another version of this struct which did not
> depend on std::locale, but simply assumed that the local used is "C".
> Something like this:
>
>             struct is_classifiedF :
>                 public predicate_facade<is_classifiedF>
>             {
>                 typedef bool result_type;
>
>                 is_classifiedF(std::ctype_base::mask Type) :
>                     m_Type(Type) {}
>
>                 template<typename CharT>
>                 bool operator()( CharT Ch ) const
>                 {
>                     // Write something here
>                 }
>
>             private:
>                 std::ctype_base::mask m_Type;
>             };
>
> But as I do not understand the meaning/encoding of
> std::ctype_base::mask m_Type I found it hard to write the missing
> function body.
>
> So I could use some pointers/hints on how to implement this.
>
See, e.g., the GNU libstdc++ docs: <
http://gcc.gnu.org/onlinedocs/gcc-4.7.1/libstdc++/api/a00617.html>. It
is a mask of given isfoo (e.g., isalnum(), etc.) character type query
function.

-- 
VZ