ses/src/get-anonymous-intrinsics.js

Hardened JavaScript for Fearless Cooperation

import {
  FERAL_FUNCTION,
  Float32Array,
  Map,
  Set,
  String,
  getOwnPropertyDescriptor,
  getPrototypeOf,
  iterateArray,
  iterateMap,
  iterateSet,
  iterateString,
  matchAllRegExp,
  matchAllSymbol,
  regexpPrototype,
  globalThis,
  assign,
  AsyncGeneratorFunctionInstance,
  ArrayBuffer,
} from './commons.js';
import { InertCompartment } from './compartment.js';

/**
 * Object.getConstructorOf()
 * Helper function to improve readability, similar to Object.getPrototypeOf().
 *
 * @param {object} obj
 */
function getConstructorOf(obj) {
  return getPrototypeOf(obj).constructor;
}

// getAnonymousIntrinsics uses a utility function to construct an arguments
// object, since it cannot have one of its own and also be a const export.
function makeArguments() {
  // eslint-disable-next-line prefer-rest-params
  return arguments;
}

/**
 * getAnonymousIntrinsics()
 * Get the intrinsics not otherwise reachable by named own property
 * traversal from the global object.
 *
 * @returns {object}
 */
export const getAnonymousIntrinsics = () => {
  const InertFunction = FERAL_FUNCTION.prototype.constructor;

  // 9.2.4.1 %ThrowTypeError%

  const argsCalleeDesc = getOwnPropertyDescriptor(makeArguments(), 'callee');
  const ThrowTypeError = argsCalleeDesc && argsCalleeDesc.get;

  // 21.1.5.2 The %StringIteratorPrototype% Object

  // eslint-disable-next-line no-new-wrappers
  const StringIteratorObject = iterateString(new String());
  const StringIteratorPrototype = getPrototypeOf(StringIteratorObject);

  // 21.2.7.1 The %RegExpStringIteratorPrototype% Object
  const RegExpStringIterator =
    regexpPrototype[matchAllSymbol] && matchAllRegExp(/./);
  const RegExpStringIteratorPrototype =
    RegExpStringIterator && getPrototypeOf(RegExpStringIterator);

  // 22.1.5.2 The %ArrayIteratorPrototype% Object

  // eslint-disable-next-line no-array-constructor
  const ArrayIteratorObject = iterateArray([]);
  const ArrayIteratorPrototype = getPrototypeOf(ArrayIteratorObject);

  // 22.2.1 The %TypedArray% Intrinsic Object

  const TypedArray = getPrototypeOf(Float32Array);

  // 23.1.5.2 The %MapIteratorPrototype% Object

  const MapIteratorObject = iterateMap(new Map());
  const MapIteratorPrototype = getPrototypeOf(MapIteratorObject);

  // 23.2.5.2 The %SetIteratorPrototype% Object

  const SetIteratorObject = iterateSet(new Set());
  const SetIteratorPrototype = getPrototypeOf(SetIteratorObject);

  // 25.1.2 The %IteratorPrototype% Object

  const IteratorPrototype = getPrototypeOf(ArrayIteratorPrototype);

  // 25.2.1 The GeneratorFunction Constructor

  // eslint-disable-next-line no-empty-function
  function* GeneratorFunctionInstance() {}
  const GeneratorFunction = getConstructorOf(GeneratorFunctionInstance);

  // 25.2.3 Properties of the GeneratorFunction Prototype Object

  const Generator = GeneratorFunction.prototype;

  // 25.7.1 The AsyncFunction Constructor

  // eslint-disable-next-line no-empty-function
  async function AsyncFunctionInstance() {}
  const AsyncFunction = getConstructorOf(AsyncFunctionInstance);

  const intrinsics = {
    '%InertFunction%': InertFunction,
    '%ArrayIteratorPrototype%': ArrayIteratorPrototype,
    '%InertAsyncFunction%': AsyncFunction,
    '%Generator%': Generator,
    '%InertGeneratorFunction%': GeneratorFunction,
    '%IteratorPrototype%': IteratorPrototype,
    '%MapIteratorPrototype%': MapIteratorPrototype,
    '%RegExpStringIteratorPrototype%': RegExpStringIteratorPrototype,
    '%SetIteratorPrototype%': SetIteratorPrototype,
    '%StringIteratorPrototype%': StringIteratorPrototype,
    '%ThrowTypeError%': ThrowTypeError,
    '%TypedArray%': TypedArray,
    '%InertCompartment%': InertCompartment,
  };

  if (AsyncGeneratorFunctionInstance !== undefined) {
    // 25.3.1 The AsyncGeneratorFunction Constructor

    const AsyncGeneratorFunction = getConstructorOf(
      AsyncGeneratorFunctionInstance,
    );

    // 25.3.2.2 AsyncGeneratorFunction.prototype
    const AsyncGenerator = AsyncGeneratorFunction.prototype;
    // 25.5.1 Properties of the AsyncGenerator Prototype Object
    const AsyncGeneratorPrototype = AsyncGenerator.prototype;
    const AsyncIteratorPrototype = getPrototypeOf(AsyncGeneratorPrototype);

    assign(intrinsics, {
      '%AsyncGenerator%': AsyncGenerator,
      '%InertAsyncGeneratorFunction%': AsyncGeneratorFunction,
      '%AsyncGeneratorPrototype%': AsyncGeneratorPrototype,
      '%AsyncIteratorPrototype%': AsyncIteratorPrototype,
    });
  }

  if (globalThis.Iterator) {
    intrinsics['%IteratorHelperPrototype%'] = getPrototypeOf(
      // eslint-disable-next-line @endo/no-polymorphic-call
      globalThis.Iterator.from([]).take(0),
    );
    intrinsics['%WrapForValidIteratorPrototype%'] = getPrototypeOf(
      // eslint-disable-next-line @endo/no-polymorphic-call
      globalThis.Iterator.from({
        next() {
          return { value: undefined };
        },
      }),
    );
  }

  if (globalThis.AsyncIterator) {
    intrinsics['%AsyncIteratorHelperPrototype%'] = getPrototypeOf(
      // eslint-disable-next-line @endo/no-polymorphic-call
      globalThis.AsyncIterator.from([]).take(0),
    );
    intrinsics['%WrapForValidAsyncIteratorPrototype%'] = getPrototypeOf(
      // eslint-disable-next-line @endo/no-polymorphic-call
      globalThis.AsyncIterator.from({ next() {} }),
    );
  }

  const ab = new ArrayBuffer(0);
  // @ts-expect-error TODO How do I add sliceToImmutable to ArrayBuffer type?
  // eslint-disable-next-line @endo/no-polymorphic-call
  const iab = ab.sliceToImmutable();
  const iabProto = getPrototypeOf(iab);
  if (iabProto !== ArrayBuffer.prototype) {
    // In a native implementation, these will be the same prototype
    intrinsics['%ImmutableArrayBufferPrototype%'] = iabProto;
  }

  return intrinsics;
};