diff options
Diffstat (limited to 'libstdc++-v3/docs/html/22_locale/ctype.html')
| -rw-r--r-- | libstdc++-v3/docs/html/22_locale/ctype.html | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/libstdc++-v3/docs/html/22_locale/ctype.html b/libstdc++-v3/docs/html/22_locale/ctype.html new file mode 100644 index 00000000000..08be102fe26 --- /dev/null +++ b/libstdc++-v3/docs/html/22_locale/ctype.html @@ -0,0 +1,146 @@ +<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 + + |