Makes the input system use an assoc list instead of a rolling buffer (#13466)

code/modules/keybindings/bindings_carbon.dm

@@ -1,10 +1,9 @@
 /mob/living/carbon/key_down(_key, client/user)
-	user.keys_held[_key] = world.time
 	if(!user.keys_held["Shift"])
 		switch(_key)
 			if("R", "Southwest") // Southwest is End
 				toggle_throw_mode()
-				return	
+				return
 			if("1")
 				a_intent_change("help")
 				return

code/modules/keybindings/bindings_client.dm

@@ -35,14 +35,13 @@
 		message_admins("Client [ckey] just attempted to send an invalid keypress. Keymessage was over [MAX_KEYPRESS_COMMANDLENGTH] characters, autokicking due to likely abuse.")
 		qdel(src)
 		return
-	//offset by 1 because the buffer address is 0 indexed because the math was simpler
-	keys_held[current_key_address + 1] = _key
+
+	if(length(keys_held) > HELD_KEY_BUFFER_LENGTH)
+		return
+
 	//the time a key was pressed isn't actually used anywhere (as of 2019-9-10) but this allows easier access usage/checking
-
 	keys_held[_key] = world.time
 
-	current_key_address = ((current_key_address + 1) % HELD_KEY_BUFFER_LENGTH)
-
 	var/movement = SSinput.movement_keys[_key]
 	if (prefs.toggles & PREFTOGGLE_AZERTY) movement = SSinput.alt_movement_keys[_key]
 	if(!(next_move_dir_sub & movement) && !keys_held["Ctrl"])
@@ -79,11 +78,8 @@
 /client/verb/keyUp(_key as text)
 	set instant = TRUE
 	set hidden = TRUE
-	//Can't just do a remove because it would alter the length of the rolling buffer, instead search for the key then null it out if it exists
-	for(var/i in 1 to HELD_KEY_BUFFER_LENGTH)
-		if(keys_held[i] == _key)
-			keys_held[i] = null
-			break
+
+	keys_held -= _key
 	var/movement = SSinput.movement_keys[_key]
 	if (prefs.toggles & PREFTOGGLE_AZERTY) movement = SSinput.alt_movement_keys[_key]
 	if(!(next_move_dir_add & movement))

code/modules/keybindings/setup.dm

@@ -1,8 +1,6 @@
 /client
-	/// A rolling buffer of any keys held currently
+	/// An assoc list of any keys held currently
 	var/list/keys_held = list()
-	///used to keep track of the current rolling buffer position
-	var/current_key_address = 0
 	/// These next two vars are to apply movement for keypresses and releases made while move delayed.
 	/// Because discarding that input makes the game less responsive.
 	/// On next move, add this dir to the move that would otherwise be done
@@ -36,10 +34,8 @@
 /client/proc/set_macros()
 	set waitfor = FALSE
 
-	//Reset and populate the rolling buffer
+	//Reset the assoc list
 	keys_held.Cut()
-	for(var/i in 1 to HELD_KEY_BUFFER_LENGTH)
-		keys_held += null
 
 	erase_all_macros()