perf(automod): also merge regexes in match_links, match_words

backend/src/utils/mergeRegexes.ts

@@ -0,0 +1,17 @@
+import { categorize } from "./categorize";
+
+const hasBackreference = /(?:^|[^\\]|[\\]{2})\\\d+/;
+
+export function mergeRegexes(sourceRegexes: RegExp[], flags: string): RegExp[] {
+  const categories = categorize(sourceRegexes, {
+    hasBackreferences: (regex) => hasBackreference.exec(regex.source) !== null,
+    safeToMerge: () => true,
+  });
+  const regexes: RegExp[] = [];
+  if (categories.safeToMerge.length) {
+    const merged = categories.safeToMerge.map((r) => `(?:${r.source})`).join("|");
+    regexes.push(new RegExp(merged, flags));
+  }
+  regexes.push(...categories.hasBackreferences);
+  return regexes;
+}

backend/src/utils/mergeWordsIntoRegex.ts

@@ -0,0 +1,6 @@
+import escapeStringRegexp from "escape-string-regexp";
+
+export function mergeWordsIntoRegex(words: string[], flags?: string) {
+  const source = words.map((word) => `(?:${escapeStringRegexp(word)})`).join("|");
+  return new RegExp(source, flags);
+}