kmx git

state: Capitalization transformation in xkb_state_key_get_syms

Previously `xkb_state_key_get_syms()` did not perform capitalization
tranformation, while `xkb_state_key_get_one_sym()` does perform it.

This is unfortunate if we want to promote the use of multiple keysyms
per levels.

The API make it difficult to change now though: we return a pointer to
an immutable array rather than filling a buffer. While we could use an
internal buffer in `xkb_state`, this option would limit the API to
*sequential* calls of `xkb_state_key_get_syms()` or require some buffer
handling (e.g. rotation).

Instead we now store the capitalization directly in `xkb_level`. We
modified `xkb_level` like so (see below for discussion about the size):

```diff
 struct xkb_level {
-    unsigned int num_syms;
+    uint16_t     num_syms;
-    unsigned int num_actions;
+    uint16_t     num_actions;
+    union {
+        /** num_syms == 1: Upper keysym */
+        xkb_keysym_t upper;
+        /** num_syms >  1: Indicate if `syms` contains the upper case
+         *                 keysyms after the lower ones. */
+        bool has_upper;
+    };
     union {
         xkb_keysym_t sym;          /* num_syms == 1 */
         xkb_keysym_t *syms;        /* num_syms > 1  */
     } s;
     union {
         union xkb_action action;   /* num_actions == 1 */
         union xkb_action *actions; /* num_actions >  1 */
     } a;
 };
```

- When `level.num_syms` <= 1, we store the upper keysym in `level.upper`.
- Else if there no cased syms, we set `level.has_upper` to false.
- Else if there are some cased syms, we set `level.has_upper`` to `true`
  and we double the original size of `level.s.syms`, but *without*
  modifying `level.num_syms`. We then append the transformed keysyms
  right after the original ones, so that we can access them by a simple
  pointer operation: `level.s.syms + level.num_syms`.

The memory footprint is *unchanged*, thanks to the reduced fields for
actions and keysyms counts.
kc3-lang/libxkbcommon/changes/api/552.feature.md

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changes/api/552.feature.md
