refactor: add optional max length to parse expensimark

README.md

@@ -20,7 +20,7 @@ npm install @expensify/react-native-live-markdown react-native-worklets expensif
 npx expo install @expensify/react-native-live-markdown react-native-worklets expensify-common html-entities@2.5.3
 ```
 
-React Native Live Markdown requires [react-native-worklets](https://github.com/software-mansion/react-native-reanimated/tree/main/packages/react-native-worklets) 0.7.0 or newer as well as [expensify-common](https://github.com/Expensify/expensify-common) 2.0.115 and [html-entities](https://github.com/mdevils/html-entities) 2.5.3 exactly if using the default built-in ExpensiMark parser.
+React Native Live Markdown requires [react-native-worklets](https://github.com/software-mansion/react-native-reanimated/tree/main/packages/react-native-worklets) 0.7.0 or newer as well as [expensify-common](https://github.com/Expensify/expensify-common) 2.0.201 or newer and [html-entities](https://github.com/mdevils/html-entities) 2.5.3 exactly if using the default built-in ExpensiMark parser.
 
 > [!IMPORTANT]
 > Please follow the `react-native-worklets` [Getting Started](https://docs.swmansion.com/react-native-worklets/docs/fundamentals/getting-started/#react-native-community-cli) guide to avoid issues.
@@ -55,6 +55,16 @@ export default function App() {
 }
 ```
 
+The built-in `parseExpensiMark` parser accepts an optional maximum input length. It defaults to 4,000 characters and returns no formatting ranges when the input is longer than the configured limit. To use a different limit, wrap the parser in a worklet function:
+
+```ts
+function parser(input: string) {
+  'worklet';
+
+  return parseExpensiMark(input, 5000);
+}
+```
+
 ## Styling
 
 `MarkdownTextInput` can be styled using `style` prop just like regular `TextInput` component.

package.json

@@ -92,7 +92,7 @@
     "eslint-plugin-promise": "^6.1.1",
     "eslint-plugin-react-native": "^5.0.0",
     "eslint-plugin-tsdoc": "^0.2.17",
-    "expensify-common": "2.0.189",
+    "expensify-common": "2.0.201",
     "jest": "^29.6.3",
     "jest-environment-jsdom": "^29.7.0",
     "nodemon": "^3.1.3",
@@ -109,7 +109,7 @@
     "typescript": "^5.8.3"
   },
   "peerDependencies": {
-    "expensify-common": ">=2.0.189",
+    "expensify-common": ">=2.0.201",
     "react": "*",
     "react-native": "*",
     "react-native-worklets": ">=0.7.0"

src/__tests__/parseExpensiMark.test.ts

@@ -37,6 +37,28 @@ test('no formatting', () => {
   expect('Hello, world!').toBeParsedAs([]);
 });
 
+describe('maximum parsable length', () => {
+  const createBoldMarkdown = (length: number) => `*${'a'.repeat(length - 2)}*`;
+  const getBoldRanges = (length: number): MarkdownRange[] => [
+    {type: 'syntax', start: 0, length: 1},
+    {type: 'bold', start: 1, length: length - 2},
+    {type: 'syntax', start: length - 1, length: 1},
+  ];
+
+  test('keeps the default 4000-character limit', () => {
+    expect(parseExpensiMark(createBoldMarkdown(4000))).toEqual(getBoldRanges(4000));
+    expect(parseExpensiMark(createBoldMarkdown(4001))).toEqual([]);
+  });
+
+  test('uses the caller-provided maximum length', () => {
+    const markdown = createBoldMarkdown(5000);
+
+    expect(parseExpensiMark(markdown)).toEqual([]);
+    expect(parseExpensiMark(markdown, 5000)).toEqual(getBoldRanges(5000));
+    expect(parseExpensiMark(`${markdown}a`, 5000)).toEqual([]);
+  });
+});
+
 describe('parsing error', () => {
   expect(`> [exa\nmple.com](https://example.com)`).toBeParsedAs([
     {type: 'blockquote', start: 0, length: 6},

src/parseExpensiMark.ts

@@ -238,8 +238,15 @@ function parseTreeToTextAndRanges(tree: StackItem): [string, MarkdownRange[]] {
   return [text, ranges];
 }
 
-function parseExpensiMark(markdown: string): MarkdownRange[] {
-  if (markdown.length > MAX_PARSABLE_LENGTH) {
+/**
+ * Parses Markdown text into formatting ranges using ExpensiMark.
+ *
+ * @param markdown - The raw Markdown string to parse.
+ * @param maxLength - Maximum input length to parse; longer input returns `[]` without parsing. Defaults to 4000.
+ * @returns The list of formatting ranges, or `[]` if input exceeds `maxLength` or fails to parse.
+ */
+function parseExpensiMark(markdown: string, maxLength = MAX_PARSABLE_LENGTH): MarkdownRange[] {
+  if (markdown.length > maxLength) {
     return [];
   }
   const html = parseMarkdownToHTML(markdown);