<section id="std.localization.facet.ctype" xreflabel="ctype">
<?dbhtml filename="ctype.html"?>

<sectioninfo>
  <keywordset>
    <keyword>
      ISO C++
    </keyword>
    <keyword>
      ctype
    </keyword>
  </keywordset>
</sectioninfo>

<title>ctype</title>

<section id="facet.ctype.impl">
<title>Implementation</title>

  <section>
    <title>Specializations</title>

<para>
For the required specialization codecvt&lt;wchar_t, char, mbstate_t&gt; ,
conversions are made between the internal character set (always UCS4
on GNU/Linux) and whatever the currently selected locale for the
LC_CTYPE category implements.
</para>

<para>
The two required specializations are implemented as follows:
</para>

<para>
<code>
ctype&lt;char&gt;
</code>
</para>
<para>
This is simple specialization. Implementing this was a piece of cake.
</para>

<para>
<code>
ctype&lt;wchar_t&gt;
</code>
</para>
<para>
This specialization, by specifying all the template parameters, pretty
much ties the hands of implementors. As such, the implementation is
straightforward, involving mcsrtombs for the conversions between char
to wchar_t and wcsrtombs for conversions between wchar_t and char.
</para>

<para>
Neither of these two required specializations deals with Unicode
characters.
</para>

  </section>
</section>

<section id="facet.ctype.future">
<title>Future</title>


<itemizedlist>
   <listitem>
   <para>
   How to deal with the global locale issue?
   </para></listitem>

   <listitem>
   <para>
   How to deal with different types than char, wchar_t? </para></listitem>

   <listitem><para>
   Overlap between codecvt/ctype: narrow/widen
   </para></listitem>

   <listitem>
     <para>
       Mask typedef in codecvt_base, argument types in codecvt.  what
       is know about this type?
   </para></listitem>

   <listitem>
   <para>
   Why mask* argument in codecvt?
   </para></listitem>

   <listitem>
     <para>
       Can this be made (more) generic? is there a simple way to
       straighten out the configure-time mess that is a by-product of
       this class?
   </para></listitem>

   <listitem>
     <para>
       Get the ctype&lt;wchar_t&gt;::mask stuff under control. Need to
       make some kind of static table, and not do lookup every time
       somebody hits the do_is... functions. Too bad we can't just
       redefine mask for ctype&lt;wchar_t&gt;
   </para></listitem>

   <listitem>
     <para>
       Rename abstract base class. See if just smash-overriding is a
       better approach. Clarify, add sanity to naming.
     </para>
   </listitem>

</itemizedlist>


</section>


<bibliography id="facet.ctype.biblio">
<title>Bibliography</title>

  <biblioentry>
    <title>
      The GNU C Library
    </title>
    <author>
      <surname>McGrath</surname>
      <firstname>Roland</firstname>
    </author>
    <author>
      <surname>Drepper</surname>
      <firstname>Ulrich</firstname>
    </author>
    <copyright>
      <year>2007</year>
      <holder>FSF</holder>
    </copyright>
    <pagenums>Chapters 6  Character Set Handling and 7 Locales and Internationalization</pagenums>
  </biblioentry>

  <biblioentry>
    <title>
      Correspondence
    </title>
    <author>
      <surname>Drepper</surname>
      <firstname>Ulrich</firstname>
    </author>
    <copyright>
      <year>2002</year>
      <holder></holder>
    </copyright>
  </biblioentry>

  <biblioentry>
    <title>
      ISO/IEC 14882:1998 Programming languages - C++
    </title>
    <copyright>
      <year>1998</year>
      <holder>ISO</holder>
    </copyright>
  </biblioentry>

  <biblioentry>
    <title>
      ISO/IEC 9899:1999 Programming languages - C
    </title>
    <copyright>
      <year>1999</year>
      <holder>ISO</holder>
    </copyright>
  </biblioentry>

  <biblioentry>
    <biblioid class="uri">
      <ulink url="http://www.unix.org/version3/ieee_std.html">
	<citetitle>
	  The Open Group Base Specifications, Issue 6 (IEEE Std. 1003.1-2004)
	</citetitle>
      </ulink>
    </biblioid>
    <copyright>
      <year>1999</year>
      <holder>
      The Open Group/The Institute of Electrical and Electronics Engineers, Inc.</holder>
    </copyright>
  </biblioentry>

  <biblioentry>
    <title>
      The C++ Programming Language, Special Edition
    </title>
    <author>
      <surname>Stroustrup</surname>
      <firstname>Bjarne</firstname>
    </author>
    <copyright>
      <year>2000</year>
      <holder>Addison Wesley, Inc.</holder>
    </copyright>
    <pagenums>Appendix D</pagenums>
    <publisher>
      <publishername>
	Addison Wesley
      </publishername>
    </publisher>
  </biblioentry>

  <biblioentry>
    <title>
      Standard C++ IOStreams and Locales
    </title>
    <subtitle>
      Advanced Programmer's Guide and Reference
    </subtitle>
    <author>
      <surname>Langer</surname>
      <firstname>Angelika</firstname>
    </author>
    <author>
      <surname>Kreft</surname>
      <firstname>Klaus</firstname>
    </author>
    <copyright>
      <year>2000</year>
      <holder>Addison Wesley Longman, Inc.</holder>
    </copyright>
    <publisher>
      <publishername>
	Addison Wesley Longman
      </publishername>
    </publisher>
  </biblioentry>

</bibliography>

</section>
