Build player-action mapping dynamically

Previously there was a constant dictionary mapping player enum × short
action name to full action name. This is very simple but is tedious to
keep updated as more actions are added.

Instead, build the mapping dynamically from a constant array of short
action names, and improve the actions.gd documentation.

As it stands this is a bit longer than writing it out by hand, but
future commits which will add new actions become one-liners.

Author: wjt

scripts/actions.gd

@@ -1,55 +1,54 @@
 extends Node
 ## Registry of action names for each player
 ##
-## This game has actions preconfigured for two players. The [class Player] scene can be configured
+## This game has actions preconfigured for two players. The [Player] scene can be configured
 ## to respond to inputs for player one or two, or for both players.
 ## [br][br]
-## Use [member lookup] to find the full action name for a given player and action.
-
-const _PLAYER_ACTIONS = {
-	Global.Player.ONE:
-	{
-		"jump": &"player_1_jump",
-		"left": &"player_1_left",
-		"right": &"player_1_right",
-	},
-	Global.Player.TWO:
-	{
-		"jump": &"player_2_jump",
-		"left": &"player_2_left",
-		"right": &"player_2_right",
-	},
-	Global.Player.BOTH:
-	{
-		"jump": &"player_both_jump",
-		"left": &"player_both_left",
-		"right": &"player_both_right",
-	},
-}
-
-
-func _ready() -> void:
-	_setup_both_actions()
-
-
-# Sets up the "both" actions, bound to the corresponding events from both players one and two.
-# This is done dynamically so that we don't have to keep them in sync in the project settings.
-func _setup_both_actions() -> void:
-	for action: String in _PLAYER_ACTIONS[Global.Player.BOTH]:
-		var p1: StringName = _PLAYER_ACTIONS[Global.Player.ONE][action]
-		var p2: StringName = _PLAYER_ACTIONS[Global.Player.TWO][action]
-		var both: StringName = _PLAYER_ACTIONS[Global.Player.BOTH][action]
+## Use [method lookup] to find the full action name for a given player and action.
+
+## Short names for actions available to each player. Use [method lookup] to find the full action
+## name for a given player and action.
+const ACTIONS = [
+	&"jump",
+	&"left",
+	&"right",
+]
+
+# Dictionary[Global.Player, Dictionary[StringName, StringName]]
+# e.g. _player_actions[Global.Player.ONE][&"jump"] == &"player_1_jump"
+@onready var _player_actions = _setup_both_actions()
+
+
+# Creates the mapping from Global.Player enum & elements of ACTIONS to full action name, and creates
+# the "both" actions bound to the combination of events for players one and two. This is done
+# dynamically so that we don't have to keep them in sync in the project settings.
+func _setup_both_actions() -> Dictionary[Global.Player, Dictionary]:
+	var player_actions: Dictionary[Global.Player, Dictionary] = {
+		Global.Player.ONE: {}, Global.Player.TWO: {}, Global.Player.BOTH: {}
+	}
+
+	for action: StringName in ACTIONS:
+		var p1: StringName = "player_1_" + action
+		var p2: StringName = "player_2_" + action
+		var both: StringName = "player_both_" + action
+
+		player_actions[Global.Player.ONE][action] = p1
+		player_actions[Global.Player.TWO][action] = p2
+		player_actions[Global.Player.BOTH][action] = both
 
 		var deadzone := maxf(InputMap.action_get_deadzone(p1), InputMap.action_get_deadzone(p2))
 		InputMap.add_action(both, deadzone)
 
 		for event: InputEvent in InputMap.action_get_events(p1) + InputMap.action_get_events(p2):
 			InputMap.action_add_event(both, event)
 
+	return player_actions
 
-## Looks up the full action name for [param player] and [param action].
+
+## Looks up the full action name for [param player] and [param action]. These full names can be
+## passed to methods such as [method Input.is_action_pressed].
 ## [br][br]
 ## For example, [code]Actions.lookup(Global.Player.TWO, "jump")[/code] returns
 ## [code]"player_2_jump"[/code].
 func lookup(player: Global.Player, action: StringName) -> StringName:
-	return _PLAYER_ACTIONS[player][action]
+	return _player_actions[player][action]