feat(common): repentance+ check functions

Author: Zamiell

packages/isaac-typescript-definitions/src/types/main.d.ts

@@ -32,3 +32,11 @@ declare function StartDebug(): void;
  * @deprecated
  */
 declare const REPENTANCE: never;
+
+/**
+ * This can be overwritten by other mods, so it is not safe to use. Use the `isRepentancePlus`
+ * helper function instead.
+ *
+ * @deprecated
+ */
+declare const REPENTANCE_PLUS: never;

packages/isaacscript-common/src/functions/utils.ts

@@ -1,3 +1,4 @@
+import { game } from "../core/cachedClasses";
 import { ReadonlySet } from "../types/ReadonlySet";
 import { getAllPlayers } from "./playerIndex";
 import { isFunction } from "./types";
@@ -155,7 +156,7 @@ export function isMultiplayer(): boolean {
 }
 
 /**
- * Helper function to check if the player is using Afterbirth+ or Repentance.
+ * Helper function to check if the player has the Repentance DLC installed.
  *
  * This function should always be used over the `REPENTANCE` constant, since the latter is not safe.
  *
@@ -181,6 +182,23 @@ export function isRepentance(): boolean {
   return isFunction(getAnimation);
 }
 
+/**
+ * Helper function to check if the player has the Repentance+ DLC installed.
+ *
+ * This function should always be used over the `REPENTANCE_PLUS` constant, since the latter is not
+ * safe.
+ *
+ * Specifically, this function checks for `Room:DamageGridWithSource` method:
+ * https://bindingofisaacrebirth.wiki.gg/wiki/The_Binding_of_Isaac:_Repentance%2B#Modding_Changes
+ */
+export function isRepentancePlus(): boolean {
+  const room = game.GetRoom();
+  const metatable = getmetatable(room) as LuaMap<string, unknown> | undefined;
+  assertDefined(metatable, "Failed to get the metatable of the room class.");
+  const damageGridWithSource = metatable.get("DamageGridWithSource");
+  return isFunction(damageGridWithSource);
+}
+
 /**
  * Helper function to check if the player is using REPENTOGON, an exe-hack which expands the modding
  * API.