ctypeISO C++ctypeImplementationSpecializations
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.
The two required specializations are implemented as follows:
ctype<char>
This is simple specialization. Implementing this was a piece of cake.
ctype<wchar_t>
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.
Neither of these two required specializations deals with Unicode
characters.
Future
How to deal with the global locale issue?
How to deal with types other than char, wchar_t?
Overlap between codecvt/ctype: narrow/widen
mask typedef in codecvt_base,
argument types in codecvt. what is know about this type?
Why mask* argument in codecvt?
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?
Get the ctype<wchar_t>::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<wchar_t>
Rename abstract base class. See if just smash-overriding is a
better approach. Clarify, add sanity to naming.
Bibliography
The GNU C Library
McGrathRolandDrepperUlrich2007FSFChapters 6 Character Set Handling and 7 Locales and Internationalization
Correspondence
DrepperUlrich2002
ISO/IEC 14882:1998 Programming languages - C++
1998ISO
ISO/IEC 9899:1999 Programming languages - C
1999ISO
The Open Group Base Specifications, Issue 6 (IEEE Std. 1003.1-2004)
1999
The Open Group/The Institute of Electrical and Electronics Engineers, Inc.
The C++ Programming Language, Special Edition
StroustrupBjarne2000Addison Wesley, Inc.Appendix D
Addison Wesley
Standard C++ IOStreams and Locales
Advanced Programmer's Guide and Reference
LangerAngelikaKreftKlaus2000Addison Wesley Longman, Inc.
Addison Wesley Longman