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1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter��15.��Facets aka Categories</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><meta name="keywords" content=" ISO C++ , library " /><link rel="home" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="localization.html" title="Part��VI.�� Localization" /><link rel="prev" href="locales.html" title="Chapter��14.��Locales" /><link rel="next" href="codecvt.html" title="codecvt" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter��15.��Facets aka Categories</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="locales.html">Prev</a>��</td><th width="60%" align="center">Part��VI.�� 4 Localization 5 6</th><td width="20%" align="right">��<a accesskey="n" href="codecvt.html">Next</a></td></tr></table><hr /></div><div class="chapter" title="Chapter��15.��Facets aka Categories"><div class="titlepage"><div><div><h2 class="title"><a id="manual.localization.facet"></a>Chapter��15.��Facets aka Categories</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="facets.html#manual.localization.facet.ctype">ctype</a></span></dt><dd><dl><dt><span class="sect2"><a href="facets.html#facet.ctype.impl">Implementation</a></span></dt><dt><span class="sect2"><a href="facets.html#facet.ctype.future">Future</a></span></dt></dl></dd><dt><span class="sect1"><a href="codecvt.html">codecvt</a></span></dt><dd><dl><dt><span class="sect2"><a href="codecvt.html#facet.codecvt.req">Requirements</a></span></dt><dt><span class="sect2"><a href="codecvt.html#facet.codecvt.design">Design</a></span></dt><dt><span class="sect2"><a href="codecvt.html#facet.codecvt.impl">Implementation</a></span></dt><dt><span class="sect2"><a href="codecvt.html#facet.codecvt.use">Use</a></span></dt><dt><span class="sect2"><a href="codecvt.html#facet.codecvt.future">Future</a></span></dt></dl></dd><dt><span class="sect1"><a href="messages.html">messages</a></span></dt><dd><dl><dt><span class="sect2"><a href="messages.html#facet.messages.req">Requirements</a></span></dt><dt><span class="sect2"><a href="messages.html#facet.messages.design">Design</a></span></dt><dt><span class="sect2"><a href="messages.html#facet.messages.impl">Implementation</a></span></dt><dt><span class="sect2"><a href="messages.html#facet.messages.use">Use</a></span></dt><dt><span class="sect2"><a href="messages.html#facet.messages.future">Future</a></span></dt></dl></dd></dl></div><div class="sect1" title="ctype"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.localization.facet.ctype"></a>ctype</h2></div></div></div><div class="sect2" title="Implementation"><div class="titlepage"><div><div><h3 class="title"><a id="facet.ctype.impl"></a>Implementation</h3></div></div></div><div class="sect3" title="Specializations"><div class="titlepage"><div><div><h4 class="title"><a id="id602134"></a>Specializations</h4></div></div></div><p> 7For the required specialization codecvt<wchar_t, char, mbstate_t> , 8conversions are made between the internal character set (always UCS4 9on GNU/Linux) and whatever the currently selected locale for the 10LC_CTYPE category implements. 11</p><p> 12The two required specializations are implemented as follows: 13</p><p> 14<code class="code"> 15ctype<char> 16</code> 17</p><p> 18This is simple specialization. Implementing this was a piece of cake. 19</p><p> 20<code class="code"> 21ctype<wchar_t> 22</code> 23</p><p> 24This specialization, by specifying all the template parameters, pretty 25much ties the hands of implementors. As such, the implementation is 26straightforward, involving mcsrtombs for the conversions between char 27to wchar_t and wcsrtombs for conversions between wchar_t and char. 28</p><p> 29Neither of these two required specializations deals with Unicode 30characters. 31</p></div></div><div class="sect2" title="Future"><div class="titlepage"><div><div><h3 class="title"><a id="facet.ctype.future"></a>Future</h3></div></div></div><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p> 32 How to deal with the global locale issue? 33 </p></li><li class="listitem"><p> 34 How to deal with different types than char, wchar_t? </p></li><li class="listitem"><p> 35 Overlap between codecvt/ctype: narrow/widen 36 </p></li><li class="listitem"><p> 37 Mask typedef in codecvt_base, argument types in codecvt. what 38 is know about this type? 39 </p></li><li class="listitem"><p> 40 Why mask* argument in codecvt? 41 </p></li><li class="listitem"><p> 42 Can this be made (more) generic? is there a simple way to 43 straighten out the configure-time mess that is a by-product of 44 this class? 45 </p></li><li class="listitem"><p> 46 Get the ctype<wchar_t>::mask stuff under control. Need to 47 make some kind of static table, and not do lookup every time 48 somebody hits the do_is... functions. Too bad we can't just 49 redefine mask for ctype<wchar_t> 50 </p></li><li class="listitem"><p> 51 Rename abstract base class. See if just smash-overriding is a 52 better approach. Clarify, add sanity to naming. 53 </p></li></ul></div></div><div class="bibliography" title="Bibliography"><div class="titlepage"><div><div><h3 class="title"><a id="facet.ctype.biblio"></a>Bibliography</h3></div></div></div><div class="biblioentry" title="The GNU C Library"><a id="id721212"></a><p><span class="title"><i> 54 The GNU C Library 55 </i>. </span><span class="author"><span class="firstname">Roland</span> <span class="surname">McGrath</span>. </span><span class="author"><span class="firstname">Ulrich</span> <span class="surname">Drepper</span>. </span><span class="copyright">Copyright �� 2007 FSF. </span><span class="pagenums">Chapters 6 Character Set Handling and 7 Locales and Internationalization. </span></p></div><div class="biblioentry" title="Correspondence"><a id="id611041"></a><p><span class="title"><i> 56 Correspondence 57 </i>. </span><span class="author"><span class="firstname">Ulrich</span> <span class="surname">Drepper</span>. </span><span class="copyright">Copyright �� 2002 . </span></p></div><div class="biblioentry" title="ISO/IEC 14882:1998 Programming languages - C++"><a id="id612309"></a><p><span class="title"><i> 58 ISO/IEC 14882:1998 Programming languages - C++ 59 </i>. </span><span class="copyright">Copyright �� 1998 ISO. </span></p></div><div class="biblioentry" title="ISO/IEC 9899:1999 Programming languages - C"><a id="id612328"></a><p><span class="title"><i> 60 ISO/IEC 9899:1999 Programming languages - C 61 </i>. </span><span class="copyright">Copyright �� 1999 ISO. </span></p></div><div class="biblioentry" title="The Open Group Base Specifications, Issue 6 (IEEE Std. 1003.1-2004)"><a id="id626861"></a><p><span class="title"><i> 62 The Open Group Base Specifications, Issue 6 (IEEE Std. 1003.1-2004) 63 </i>. </span><span class="copyright">Copyright �� 1999 64 The Open Group/The Institute of Electrical and Electronics Engineers, Inc.. </span><span class="biblioid"> 65 <a class="ulink" href="http://www.unix.org/version3/ieee_std.html" target="_top"> 66 </a> 67 . </span></p></div><div class="biblioentry" title="The C++ Programming Language, Special Edition"><a id="id626888"></a><p><span class="title"><i> 68 The C++ Programming Language, Special Edition 69 </i>. </span><span class="author"><span class="firstname">Bjarne</span> <span class="surname">Stroustrup</span>. </span><span class="copyright">Copyright �� 2000 Addison Wesley, Inc.. </span><span class="pagenums">Appendix D. </span><span class="publisher"><span class="publishername"> 70 Addison Wesley 71 . </span></span></p></div><div class="biblioentry" title="Standard C++ IOStreams and Locales"><a id="id655841"></a><p><span class="title"><i> 72 Standard C++ IOStreams and Locales 73 </i>. </span><span class="subtitle"> 74 Advanced Programmer's Guide and Reference 75 . </span><span class="author"><span class="firstname">Angelika</span> <span class="surname">Langer</span>. </span><span class="author"><span class="firstname">Klaus</span> <span class="surname">Kreft</span>. </span><span class="copyright">Copyright �� 2000 Addison Wesley Longman, Inc.. </span><span class="publisher"><span class="publishername"> 76 Addison Wesley Longman 77 . </span></span></p></div></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="locales.html">Prev</a>��</td><td width="20%" align="center"><a accesskey="u" href="localization.html">Up</a></td><td width="40%" align="right">��<a accesskey="n" href="codecvt.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter��14.��Locales��</td><td width="20%" align="center"><a accesskey="h" href="../spine.html">Home</a></td><td width="40%" align="right" valign="top">��codecvt</td></tr></table></div></body></html> 78