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+<HTML>
+<HEAD>
+ <H1>
+ Notes on the ctype implementation.
+ </H1>
+</HEAD>
+<I>
+prepared by Benjamin Kosnik (bkoz@redhat.com) on August 30, 2000
+</I>
+
+<P>
+<H2>
+1. Abstract
+</H2>
+<P>
+Woe is me.
+</P>
+
+<P>
+<H2>
+2. What the standard says
+</H2>
+
+
+<P>
+<H2>
+3. Problems with "C" ctype : global locales, termination.
+</H2>
+
+<P>
+For the required specialization codecvt<wchar_t, char, mbstate_t> ,
+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.
+
+<P>
+<H2>
+4. Design
+</H2>
+The two required specializations are implemented as follows:
+
+<P>
+<TT>
+ctype<char>
+</TT>
+<P>
+This is simple specialization. Implementing this was a piece of cake.
+
+<P>
+<TT>
+ctype<wchar_t>
+</TT>
+<P>
+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.
+
+<P>
+Neither of these two required specializations deals with Unicode
+characters. As such, libstdc++-v3 implements
+
+
+
+<P>
+<H2>
+5. Examples
+</H2>
+
+<pre>
+ typedef ctype<char> cctype;
+</pre>
+
+More information can be found in the following testcases:
+<UL>
+<LI> testsuite/22_locale/ctype_char_members.cc
+<LI> testsuite/22_locale/ctype_wchar_t_members.cc
+</UL>
+
+<P>
+<H2>
+6. Unresolved Issues
+</H2>
+
+<UL>
+ <LI> how to deal with the global locale issue?
+
+ <LI> how to deal with different types than char, wchar_t?
+
+ <LI> codecvt/ctype overlap: narrow/widen
+
+ <LI> mask typedef in codecvt_base, argument types in codecvt.
+ what is know about this type?
+
+ <LI> why mask* argument in codecvt?
+
+ <LI> 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?
+
+ <LI> get the ctype<wchar_t>::mask stuff under control. Need to
+ make some kind of static table, and not do lookup evertime
+ somebody hits the do_is... functions. Too bad we can't just
+ redefine mask for ctype<wchar_t>
+
+ <LI> rename abstract base class. See if just smash-overriding
+ is a better approach. Clarify, add sanity to naming.
+
+</UL>
+
+
+<P>
+<H2>
+7. Acknowledgments
+</H2>
+Ulrich Drepper for patient answering of late-night questions, skeletal
+examples, and C language expertise.
+
+<P>
+<H2>
+8. Bibliography / Referenced Documents
+</H2>
+
+Drepper, Ulrich, GNU libc (glibc) 2.2 manual. In particular, Chapters "6. Character Set Handling" and "7 Locales and Internationalization"
+
+<P>
+Drepper, Ulrich, Numerous, late-night email correspondence
+
+<P>
+ISO/IEC 14882:1998 Programming languages - C++
+
+<P>
+ISO/IEC 9899:1999 Programming languages - C
+
+<P>
+Langer, Angelika and Klaus Kreft, Standard C++ IOStreams and Locales, Advanced Programmer's Guide and Reference, Addison Wesley Longman, Inc. 2000
+
+<P>
+Stroustrup, Bjarne, Appendix D, The C++ Programming Language, Special Edition, Addison Wesley, Inc. 2000
+
+<P>
+System Interface Definitions, Issue 6 (IEEE Std. 1003.1-200x)
+The Open Group/The Institute of Electrical and Electronics Engineers, Inc.
+http://www.opennc.org/austin/docreg.html
+
+
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