support icu messageformat for translations

build/intl-linter/rules/noNestedChoice.ts

@@ -0,0 +1,35 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { Element } from '../utils/rule';
+import { rule } from '../utils/rule';
+
+export default rule('noNestedChoice', context => {
+  let insideChoice = false;
+
+  function check(element: Element) {
+    if (insideChoice) {
+      context.report(
+        'Nested {select}/{plural} is not supported by Smartling',
+        element.location
+      );
+    }
+  }
+
+  return {
+    enterSelect(element) {
+      check(element);
+      insideChoice = true;
+    },
+    exitSelect() {
+      insideChoice = false;
+    },
+    enterPlural(element) {
+      check(element);
+      insideChoice = true;
+    },
+    exitPlural() {
+      insideChoice = false;
+    },
+  };
+});