kc3-lang/libxkbcommon

2024-03-05T10:28:11

keysyms: Fix inconsistent case-insensitive name lookup `xkb_keysym_from_name` has inconsistent behavior when used with the flag `XKB_KEYSYM_CASE_INSENSITIVE`: ```c xkb_keysym_from_name("a", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_a; xkb_keysym_from_name("A", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_a; xkb_keysym_from_name("dead_a", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_dead_A; xkb_keysym_from_name("dead_A", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_dead_A; xkb_keysym_from_name("dead_o", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_dead_o; xkb_keysym_from_name("dead_O", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_dead_o; xkb_keysym_from_name("KANA_tsu", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_kana_tsu; xkb_keysym_from_name("KANA_TSU", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_kana_tsu; xkb_keysym_from_name("KANA_ya", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_kana_YA; xkb_keysym_from_name("KANA_YA", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_kana_YA; xkb_keysym_from_name("XF86Screensaver", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_XF86ScreenSaver; xkb_keysym_from_name("XF86ScreenSaver", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_XF86ScreenSaver; ``` So currently, if two keysym names differ only by case, then the lower-case *keysym* is returned, not the keysym corresponding to the lower-case keysym *name*. Indeed, `xkb_keysym_from_name` uses `xkb_keysym_is_lower` to test if a keysym is a lower-case keysym. Let’s look at the example for keysyms `a` and `A`: we get the keysym `a` not because its name is lower case, but because `xkb_keysym_is_lower(XKB_KEY_a)` returns true and `xkb_keysym_is_lower(XKB_KEY_A)` returns false. So the results are correct according to the doc: - Katakana is not a bicameral script, so e.g. `kana_ya` is *not* the lower case of `kana_YA`. - As for the `dead_*` keysyms, they are not cased either because they do not correspond to characters. - `XF86ScreenSaver` and `XF86Screensaver` are two different keysyms. But this is also very counter-intuitive: `xkb_keysym_is_lower` is not the right function to use in this case, because one would expect to check only the name, not the corresponding character case: ```c xkb_keysym_from_name("KANA_YA", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_kana_ya; xkb_keysym_from_name("XF86ScreenSaver", XKB_KEYSYM_CASE_INSENSITIVE) == XKB_KEY_XF86Screensaver; ``` Fixed by making the order of the keysyms names consistent in `src/ks_tables.h`: 1. Sort by the casefolded name: e.g. `kana_ya` < `kana_YO`. 2. If same casefolded name, then sort by cased name, i.e for ASCII: upper before lower: e.g `kana_YA` < `kana_ya`. Thus we now have e.g. `kana_YA` < `kana_ya` < `kana_YO` < `kana_yo`. The lookup logic has also been simplified. Added exhaustive test for ambiguous case-insensitive names.