pruneNonEscapingScopes() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/PruneNonEscapingScopes.ts lines 113–136

export function pruneNonEscapingScopes(fn: ReactiveFunction): void {
  /*
   * First build up a map of which instructions are involved in creating which values,
   * and which values are returned.
   */
  const state = new State(fn.env);
  for (const param of fn.params) {
    if (param.kind === 'Identifier') {
      state.declare(param.identifier.declarationId);
    } else {
      state.declare(param.place.identifier.declarationId);
    }
  }
  visitReactiveFunction(fn, new CollectDependenciesVisitor(fn.env, state), []);

  /*
   * Then walk outward from the returned values and find all captured operands.
   * This forms the set of identifiers which should be memoized.
   */
  const memoized = computeMemoizedIdentifiers(state);

  // Prune scopes that do not declare/reassign any escaping values
  visitReactiveFunction(fn, new PruneScopesTransform(), memoized);
}