Auto-workletize React Native Gesture Handler callback functions

[tomekzaw]

Description

This PR adds support for detecting patterns in JavaScript code which are specific to React Native Gesture Handler, like Gesture.Tap().onEnd(...), so that they can be automatically converted into worklets even if they are not marked with 'worklet'; directive.

The general pattern is Gesture.Foo()[*].bar(fun), where:

• Foo is a gesture object, like Tap, Pan, Pinch, etc.
• [*] is any number of chained builder method calls (e.g. numberOfTaps(2) or onStart(...))
• bar is any builder method name, e.g. onEnd
• fun is a function declaration, function expression or arrow function expression

The following callback functions will be auto-workletized:

import { Gesture } from 'react-native-gesture-handler';

const foo = Gesture.Tap()
  .numberOfTaps(2)
  .onBegan(() => {
    // from now on, you may skip the 'worklet'; directive here...
    console.log('onBegan');
  })
  .onStart((_event) => {
    // ...and here...
    console.log('onStart');
  })
  .onEnd((_event, _success) => {
    // ...and here too!
    console.log('onEnd');
  });

Please note that the following callback functions will not be auto-workletized:

somethingNotRelatedToGestures.onEnd(( /* ... */ ) => { /* ... */ });

const tap = Gesture.Tap();
tap.onEnd((_event, success) => { /* ... */ });

const fun = (_event, success) => { /* ... */ };
Gesture.Tap().onEnd(fun);

import { Gesture as RNGHGesture } from 'react-native-gesture-handler';
RNGHGesture.Tap().onEnd((_event, success) => { /* ... */ });

In all the above cases, you still need to specify the 'worklet'; directive explicitly.

Changes

• Added processIfGestureHandlerEventCallbackFunctionNode function in babel.config.js
• Added snapshot tests for functions that should and should not be workletized

Test code and steps to reproduce

yarn jest

Checklist

• Included code example that can be used to test this change
• Updated TS types
• Added TS types tests
• Added unit / integration tests
• Updated documentation
• Ensured that CI passes

[piaskowyk]

🚀