feat(backend): DatabaseLearningObjectProvider geïmplementeerd.

backend/src/util/async.ts

@@ -0,0 +1,23 @@
+/**
+ * Replace all occurrences of regex in str with the result of asyncFn called with the matching snippet and each of
+ * the parts matched by a group in the regex as arguments.
+ *
+ * @param str The string where to replace the occurrences
+ * @param regex
+ * @param replacementFn
+ */
+export async function replaceAsync(str: string, regex: RegExp, replacementFn: (match: string, ...args: string[]) => Promise<string>) {
+    const promises: Promise<string>[] = [];
+
+    // First run through matches: add all Promises resulting from the replacement function
+    str.replace(regex, (full, ...args) => {
+        promises.push(replacementFn(full, ...args));
+        return full;
+    });
+
+    // Wait for the replacements to get loaded. Reverse them so when popping them, we work in a FIFO manner.
+    const replacements: string[] = (await Promise.all(promises));
+
+    // Second run through matches: Replace them by their previously computed replacements.
+    return str.replace(regex, () => replacements.pop()!!);
+}