4 The purpose of the rules file is to map between configuration values
5 that are easy for a user to specify and understand, and the
6 configuration values xkbcomp uses and understands.
8 xkbcomp uses the xkb_component_names struct, which maps directly to
9 include statements of the appropriate sections, called for short
10 KcCGST (see doc/keymap-format-text-v1.txt; 'G' stands for "geometry",
11 which is not supported). These are not really intuitive or straight-
12 forward for the uninitiated.
14 Instead, the user passes in a xkb_rule_names struct, which consists
15 of the name of a rules file (in Linux this is usually "evdev"), a
16 keyboard model (e.g. "pc105"), a set of layouts (which will end up
17 in different groups, e.g. "us,fr"), variants (used to alter/augment
18 the respective layout, e.g. "intl,dvorak"), and a set of options
19 (used to tweak some general behavior of the keyboard, e.g.
20 "ctrl:nocaps,compose:menu" to make the Caps Lock key act like Ctrl
21 and the Menu key like Compose). We call these RMLVO.
25 The file consists of rule sets, each consisting of rules (one per
26 line), which match the MLVO values on the left hand side, and, if
27 the values match to the values the user passed in, results in the
28 values on the right hand side being added to the resulting KcCGST.
29 Since some values are related and repeated often, it is possible
30 to group them together and refer to them by a group name in the
33 Along with matching values by simple string equality, and for
34 membership in a group defined previously, rules may also contain
35 "wildcard" values - "*" - which always match. These usually appear
40 (It might be helpful to look at a file like rules/evdev along with
41 this grammar. Comments, whitespace, etc. are not shown.)
44 File ::= { "!" (Include | Group | RuleSet) }
46 Include ::= "include" <ident>
48 Group ::= GroupName "=" { GroupElement } "\n"
49 GroupName ::= "$"<ident>
50 GroupElement ::= <ident>
52 RuleSet ::= Mapping { Rule }
54 Mapping ::= { Mlvo } "=" { Kccgst } "\n"
55 Mlvo ::= "model" | "option" | ("layout" | "variant") [ Index ]
56 Index ::= "[" 1..XKB_NUM_GROUPS "]"
57 Kccgst ::= "keycodes" | "symbols" | "types" | "compat" | "geometry"
59 Rule ::= { MlvoValue } "=" { KccgstValue } "\n"
60 MlvoValue ::= "*" | GroupName | <ident>
61 KccgstValue ::= <ident>
66 - Include processes the rules in the file path specified in the ident,
67 in order. %-expansion is performed, as follows:
74 The value of the HOME environment variable.
77 The extra lookup path for system-wide XKB data (usually /etc/xkb/rules).
80 The system-installed rules directory (usually /usr/share/X11/xkb/rules).
83 - The order of values in a Rule must be the same as the Mapping it
84 follows. The mapping line determines the meaning of the values in
85 the rules which follow in the RuleSet.
87 - If a Rule is matched, %-expansion is performed on the KccgstValue,
92 The model, layout or variant, if only one was given (e.g.
93 %l for "us,il" is invalid).
96 Layout or variant for the specified group Index, if more than
97 one was given (e.g. %l[1] for "us" is invalid).
99 %+m, %+l, %+v, %+l[1], %+v[1]
100 As above, but prefixed with '+'. Similarly, '|', '-', '_' may be
103 %(m), %(l), %(l[1]), %(v), %(v[1]):
104 As above, but prefixed by '(' and suffixed by ')'.
107 In case the expansion is invalid, as described above, it is
108 skipped (the rest of the string is still processed); this includes
109 the prefix and suffix (that's why you shouldn't use e.g. "(%v[1])").