Adds cache helper function.

data-extraction/src/js/helpers/cache.ts

@@ -0,0 +1,31 @@
+import { DataExtractorApiImpl } from "../api";
+
+const cached = new Map<string, any>();
+
+/**
+ * Evaluates an expression
+ */
+export function cache<T>(
+	expression: string | (() => T),
+	id: string | number | undefined = undefined
+): T {
+	let resultFn: () => any;
+	let key: string;
+	if (typeof expression === "string") {
+		const evalFn = DataExtractorApiImpl.lastEvalFn!;
+		resultFn = () => evalFn(expression);
+		key = JSON.stringify({ expr: expression, id });
+	} else {
+		resultFn = () => expression();
+		key = JSON.stringify({ expr: expression.toString(), id });
+	}
+
+	if (cached.has(key)) {
+		return cached.get(key);
+	}
+
+	const result = resultFn();
+	cached.set(key, result);
+
+	return result;
+}

data-extraction/src/js/helpers/index.ts

@@ -2,3 +2,4 @@ export * from "./createGraph";
 export * from "./createGraphFromPointers";
 export * from "./tryEval";
 export * from "./markedGrid";
+export * from "./cache";