cpython/Modules/cjkcodecs
Eric Snow 81c72044a1
bpo-46541: Replace core use of _Py_IDENTIFIER() with statically initialized global objects. (gh-30928)
We're no longer using _Py_IDENTIFIER() (or _Py_static_string()) in any core CPython code.  It is still used in a number of non-builtin stdlib modules.

The replacement is: PyUnicodeObject (not pointer) fields under _PyRuntimeState, statically initialized as part of _PyRuntime.  A new _Py_GET_GLOBAL_IDENTIFIER() macro facilitates lookup of the fields (along with _Py_GET_GLOBAL_STRING() for non-identifier strings).

https://bugs.python.org/issue46541#msg411799 explains the rationale for this change.

The core of the change is in:

* (new) Include/internal/pycore_global_strings.h - the declarations for the global strings, along with the macros
* Include/internal/pycore_runtime_init.h - added the static initializers for the global strings
* Include/internal/pycore_global_objects.h - where the struct in pycore_global_strings.h is hooked into _PyRuntimeState
* Tools/scripts/generate_global_objects.py - added generation of the global string declarations and static initializers

I've also added a --check flag to generate_global_objects.py (along with make check-global-objects) to check for unused global strings.  That check is added to the PR CI config.

The remainder of this change updates the core code to use _Py_GET_GLOBAL_IDENTIFIER() instead of _Py_IDENTIFIER() and the related _Py*Id functions (likewise for _Py_GET_GLOBAL_STRING() instead of _Py_static_string()).  This includes adding a few functions where there wasn't already an alternative to _Py*Id(), replacing the _Py_Identifier * parameter with PyObject *.

The following are not changed (yet):

* stop using _Py_IDENTIFIER() in the stdlib modules
* (maybe) get rid of _Py_IDENTIFIER(), etc. entirely -- this may not be doable as at least one package on PyPI using this (private) API
* (maybe) intern the strings during runtime init

https://bugs.python.org/issue46541
2022-02-08 13:39:07 -07:00
..
clinic bpo-37999: No longer use __int__ in implicit integer conversions. (GH-15636) 2020-05-26 18:43:38 +03:00
README bpo-40328: Add tool for generating cjk mapping headers (GH-19602) 2020-04-30 02:34:24 +09:00
_codecs_cn.c bpo-33578: Add getstate/setstate for CJK codec (GH-6984) 2018-11-01 03:48:49 -07:00
_codecs_hk.c Issue #23181: More "codepoint" -> "code point". 2015-01-18 11:28:37 +02:00
_codecs_iso2022.c bpo-31275: Small refactoring to silence a fall-through warning. (#3206) 2017-08-25 18:31:22 +02:00
_codecs_jp.c bpo-35194: Fix a wrong constant in cp932 codec (GH-10420) 2018-11-08 23:12:06 -08:00
_codecs_kr.c Issue #23181: More "codepoint" -> "code point". 2015-01-18 11:28:37 +02:00
_codecs_tw.c CJK codecs: less magical macros, semicolon is now explicit 2013-10-29 00:59:44 +01:00
alg_jisx0201.h CJK codecs: less magic macros, require explicit semicolon 2013-10-29 00:19:27 +01:00
cjkcodecs.h bpo-42866: Fix refleak in CJK getcodec() (GH-24165) 2021-01-08 15:01:38 +01:00
emu_jisx0213_2000.h CJK codecs: less magical macros, semicolon is now explicit 2013-10-29 00:59:44 +01:00
mappings_cn.h bpo-40328: Add tool for generating cjk mapping headers (GH-19602) 2020-04-30 02:34:24 +09:00
mappings_hk.h Merged revisions 60481,60485,60489-60492,60494-60496,60498-60499,60501-60503,60505-60506,60508-60509,60523-60524,60532,60543,60545,60547-60548,60552,60554,60556-60559,60561-60562,60569,60571-60572,60574,60576-60583,60585-60586,60589,60591,60594-60595,60597-60598,60600-60601,60606-60612,60615,60617-60678 via svnmerge from 2008-02-09 02:18:51 +00:00
mappings_jisx0213_pair.h bpo-40328: Add tool for generating cjk mapping headers (GH-19602) 2020-04-30 02:34:24 +09:00
mappings_jp.h bpo-40328: Add tool for generating cjk mapping headers (GH-19602) 2020-04-30 02:34:24 +09:00
mappings_kr.h bpo-40328: Add tool for generating cjk mapping headers (GH-19602) 2020-04-30 02:34:24 +09:00
mappings_tw.h - Modernize code to use Py_ssize_t more intensively. 2006-03-04 16:08:19 +00:00
multibytecodec.c bpo-46541: Replace core use of _Py_IDENTIFIER() with statically initialized global objects. (gh-30928) 2022-02-08 13:39:07 -07:00
multibytecodec.h bpo-1635741: Convert _multibytecodec to multi-phase init (GH-24095) 2021-01-04 22:33:45 +01:00

README

To generate or modify mapping headers
-------------------------------------
Mapping headers are generated from Tools/unicode/genmap_*.py



Notes on implementation characteristics of each codecs
-----------------------------------------------------

1) Big5 codec

  The big5 codec maps the following characters as cp950 does rather
  than conforming Unicode.org's that maps to 0xFFFD.

    BIG5        Unicode     Description

    0xA15A      0x2574      SPACING UNDERSCORE
    0xA1C3      0xFFE3      SPACING HEAVY OVERSCORE
    0xA1C5      0x02CD      SPACING HEAVY UNDERSCORE
    0xA1FE      0xFF0F      LT DIAG UP RIGHT TO LOW LEFT
    0xA240      0xFF3C      LT DIAG UP LEFT TO LOW RIGHT
    0xA2CC      0x5341      HANGZHOU NUMERAL TEN
    0xA2CE      0x5345      HANGZHOU NUMERAL THIRTY

  Because unicode 0x5341, 0x5345, 0xFF0F, 0xFF3C is mapped to another
  big5 codes already, a roundtrip compatibility is not guaranteed for
  them.


2) cp932 codec

  To conform to Windows's real mapping, cp932 codec maps the following
  codepoints in addition of the official cp932 mapping.

    CP932     Unicode     Description

    0x80      0x80        UNDEFINED
    0xA0      0xF8F0      UNDEFINED
    0xFD      0xF8F1      UNDEFINED
    0xFE      0xF8F2      UNDEFINED
    0xFF      0xF8F3      UNDEFINED


3) euc-jisx0213 codec

  The euc-jisx0213 codec maps JIS X 0213 Plane 1 code 0x2140 into
  unicode U+FF3C instead of U+005C as on unicode.org's mapping.
  Because euc-jisx0213 has REVERSE SOLIDUS on 0x5c already and A140
  is shown as a full width character, mapping to U+FF3C can make
  more sense.

  The euc-jisx0213 codec is enabled to decode JIS X 0212 codes on
  codeset 2. Because JIS X 0212 and JIS X 0213 Plane 2 don't have
  overlapped by each other, it doesn't bother standard conformations
  (and JIS X 0213 Plane 2 is intended to use so.) On encoding
  sessions, the codec will try to encode kanji characters in this
  order:

    JIS X 0213 Plane 1 -> JIS X 0213 Plane 2 -> JIS X 0212


4) euc-jp codec

  The euc-jp codec is a compatibility instance on these points:
   - U+FF3C FULLWIDTH REVERSE SOLIDUS is mapped to EUC-JP A1C0 (vice versa)
   - U+00A5 YEN SIGN is mapped to EUC-JP 0x5c. (one way)
   - U+203E OVERLINE is mapped to EUC-JP 0x7e. (one way)


5) shift-jis codec

  The shift-jis codec is mapping 0x20-0x7e area to U+20-U+7E directly
  instead of using JIS X 0201 for compatibility. The differences are:
   - U+005C REVERSE SOLIDUS is mapped to SHIFT-JIS 0x5c.
   - U+007E TILDE is mapped to SHIFT-JIS 0x7e.
   - U+FF3C FULL-WIDTH REVERSE SOLIDUS is mapped to SHIFT-JIS 815f.