extended-wild-cards

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Author : Pierre Le Marre
Date : 2025-03-26 10:35:22
Hash : 6fc6e64b
Message : rules: Added extended wild cards <none>, <some> and <any> Added the following wild cards to the rules file syntax, in addition to the current `*` legacy wild card: - `<none>`: Match *empty* value. - `<some>`: Match *non-empty* value. - `<any>`: Match *any* (optionally empty) value. Its behavior does not depend on the context, contrary to the legacy wild card `*`. This will enable writing much simpler rules, see [!764] for an example of tricky rules in the `xkeyboard-config` project, that would benefit from the new wild cards. [!764]: https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/merge_requests/764 The verbose wild cards are preferred to single characters: - More intuitive: self-explanatory. - Does not steal syntax from other token. - Extensible syntax, should we need it. A previous proposal used the characters (`!`, `+`, `?`) for their similarity with the corresponding syntax of regular expressions (negative assertion & quantifiers), in line with `*`. But `!` is not that intuitive after all and conflict with its role as section header. Furthermore, `+` is also used as a merge mode. Finally, nothing beats whole short words for readability.

test/data/rules/extended-wild-cards

! model = keycodes
  *     = evdev

! model = compat
  *     = complete

! model = types
  *     = complete

! model = symbols
  *     = pc

! layout[any] variant[any] = symbols
  l1          <none>       = +l10:%i             // compatibity mapping: l1, no variant
  l1          v1           = +l20:%i             // compatibity mapping: l1, specific variant
  l1          <some>       = +l30%(v[%i]):%i     // compatibity mapping: l1, some variant
  l2          *            = +l40%(v[%i]):%i     // compatibity mapping: l2, some variant (legacy)
  l3          <any>        = +l50%(v[%i]):%i     // compatibity mapping: l3, any variant (catch-all)
  *           v2           = +%l[%i](v20):%i     // compatibity mapping: specific variant
  *           <any>        = +%l[%i]%(v[%i]):%i  // catch-all

! option = symbols
  opt1   = +opt1

kc3-lang/libxkbcommon/test/data/rules/extended-wild-cards

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kc3-lang/libxkbcommon /test/data/rules/extended-wild-cards