support icu messageformat for translations

build/intl-linter/utils/traverse.ts

@@ -0,0 +1,90 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type {
+  MessageFormatElement,
+  LiteralElement,
+  ArgumentElement,
+  NumberElement,
+  DateElement,
+  TimeElement,
+  SelectElement,
+  PluralElement,
+  PoundElement,
+  TagElement,
+} from '@formatjs/icu-messageformat-parser';
+import { TYPE } from '@formatjs/icu-messageformat-parser';
+
+export type VisitorMethod<T extends MessageFormatElement> = (
+  element: T
+) => void;
+
+export type Visitor = {
+  enterLiteral?: VisitorMethod<LiteralElement>;
+  exitLiteral?: VisitorMethod<LiteralElement>;
+  enterArgument?: VisitorMethod<ArgumentElement>;
+  exitArgument?: VisitorMethod<ArgumentElement>;
+  enterNumber?: VisitorMethod<NumberElement>;
+  exitNumber?: VisitorMethod<NumberElement>;
+  enterDate?: VisitorMethod<DateElement>;
+  exitDate?: VisitorMethod<DateElement>;
+  enterTime?: VisitorMethod<TimeElement>;
+  exitTime?: VisitorMethod<TimeElement>;
+  enterSelect?: VisitorMethod<SelectElement>;
+  exitSelect?: VisitorMethod<SelectElement>;
+  enterPlural?: VisitorMethod<PluralElement>;
+  exitPlural?: VisitorMethod<PluralElement>;
+  enterPound?: VisitorMethod<PoundElement>;
+  exitPound?: VisitorMethod<PoundElement>;
+  enterTag?: VisitorMethod<TagElement>;
+  exitTag?: VisitorMethod<TagElement>;
+};
+
+export function traverse(
+  elements: Array<MessageFormatElement>,
+  visitor: Visitor
+): void {
+  for (const element of elements) {
+    if (element.type === TYPE.literal) {
+      visitor.enterLiteral?.(element);
+      visitor.exitLiteral?.(element);
+    } else if (element.type === TYPE.argument) {
+      visitor.enterArgument?.(element);
+      visitor.exitArgument?.(element);
+    } else if (element.type === TYPE.number) {
+      visitor.enterNumber?.(element);
+      visitor.exitNumber?.(element);
+    } else if (element.type === TYPE.date) {
+      visitor.enterDate?.(element);
+      visitor.exitDate?.(element);
+    } else if (element.type === TYPE.time) {
+      visitor.enterTime?.(element);
+      visitor.exitTime?.(element);
+    } else if (element.type === TYPE.select) {
+      visitor.enterSelect?.(element);
+      for (const node of Object.values(element.options)) {
+        traverse(node.value, visitor);
+      }
+      visitor.exitSelect?.(element);
+    } else if (element.type === TYPE.plural) {
+      visitor.enterPlural?.(element);
+      for (const node of Object.values(element.options)) {
+        traverse(node.value, visitor);
+      }
+      visitor.exitPlural?.(element);
+    } else if (element.type === TYPE.pound) {
+      visitor.enterPound?.(element);
+      visitor.exitPound?.(element);
+    } else if (element.type === TYPE.tag) {
+      visitor.enterTag?.(element);
+      traverse(element.children, visitor);
+      visitor.exitTag?.(element);
+    } else {
+      unreachable(element);
+    }
+  }
+}
+
+function unreachable(x: never): never {
+  throw new Error(`unreachable: ${x}`);
+}