Eric Gebhart user space and keymaps (#17487)

Co-authored-by: Drashna Jaelre <drashna@live.com>

users/ericgebhart/extensions/oneshot.h

@@ -0,0 +1,37 @@
+#define ENABLE_ONESHOT
+#ifdef ENABLE_ONESHOT
+#pragma once
+
+typedef enum {
+  ONESHOT_LCTL = 0,
+  ONESHOT_LSFT = 1,
+  ONESHOT_LALT = 2,
+  ONESHOT_LGUI = 3,
+  ONESHOT_RCTL = 4,
+  ONESHOT_RSFT = 5,
+  ONESHOT_RALT = 6,
+  ONESHOT_RGUI = 7,
+  ONESHOT_NONE = 8,
+  ONESHOT_MOD_COUNT = 8,
+} oneshot_mod;
+
+
+// This function should be called inside proces_record_user and does everything needed to get one shot modifiers working.
+// Returns true if the keycode needs further handling, false otherwise.
+int8_t update_oneshot_modifiers(uint16_t keycode, keyrecord_t *record, int8_t keycode_consumed);
+int8_t turnoff_oneshot_modifiers(void);
+
+// TO BE IMPLEMENTED BY THE USER
+// This function should return one of the oneshot_mod enumerations (see keymap.c implementation)
+oneshot_mod get_modifier_for_trigger_key(uint16_t keycode);
+
+// TO BE IMPLEMENTED BY THE USER
+// This function should return true for keycodes that must be ignored in the oneshot modifier behaviour.
+// You probably want to ignore layer keys. Trigger keys don't need to be specified here.
+bool is_oneshot_modifier_ignored_key(uint16_t keycode);
+
+// TO BE IMPLEMENTED BY THE USER
+// This function should return true for keycodes that should reset all oneshot modifiers.
+bool is_oneshot_modifier_cancel_key(uint16_t keycode);
+
+#endif