Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 941 insertions, 0 deletions

diff --git a/js/src/builtin/Iterator.js b/js/src/builtin/Iterator.js
new file mode 100644
index 0000000000..0cc6cebf18
--- /dev/null
+++ b/js/src/builtin/Iterator.js
@@ -0,0 +1,941 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+function IteratorIdentity() {
+  return this;
+}
+
+/* ECMA262 7.2.7 */
+function IteratorNext(iteratorRecord, value) {
+  // Steps 1-2.
+  var result =
+    ArgumentsLength() < 2
+      ? callContentFunction(iteratorRecord.nextMethod, iteratorRecord.iterator)
+      : callContentFunction(
+          iteratorRecord.nextMethod,
+          iteratorRecord.iterator,
+          value
+        );
+  // Step 3.
+  if (!IsObject(result)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, result);
+  }
+  // Step 4.
+  return result;
+}
+
+// https://tc39.es/ecma262/#sec-getiterator
+function GetIterator(obj, isAsync, method) {
+  // Step 1. If hint is not present, set hint to sync.
+  // Step 2. If method is not present, then
+  if (!method) {
+    // Step 2.a. If hint is async, then
+    if (isAsync) {
+      // Step 2.a.i. Set method to ? GetMethod(obj, @@asyncIterator).
+      method = GetMethod(obj, GetBuiltinSymbol("asyncIterator"));
+
+      // Step 2.a.ii. If method is undefined, then
+      if (!method) {
+        // Step 2.a.ii.1. Let syncMethod be ? GetMethod(obj, @@iterator).
+        var syncMethod = GetMethod(obj, GetBuiltinSymbol("iterator"));
+
+        // Step 2.a.ii.2. Let syncIteratorRecord be ? GetIterator(obj, sync, syncMethod).
+        var syncIteratorRecord = GetIterator(obj, false, syncMethod);
+
+        // Step 2.a.ii.2. Return CreateAsyncFromSyncIterator(syncIteratorRecord).
+        return CreateAsyncFromSyncIterator(syncIteratorRecord.iterator, syncIteratorRecord.nextMethod);
+      }
+    } else {
+      // Step 2.b. Otherwise, set method to ? GetMethod(obj, @@iterator).
+      method = GetMethod(obj, GetBuiltinSymbol("iterator"));
+    }
+  }
+
+  // Step 3. Let iterator be ? Call(method, obj).
+  var iterator = callContentFunction(method, obj);
+
+  // Step 4. If Type(iterator) is not Object, throw a TypeError exception.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_NOT_ITERABLE, obj === null ? "null" : typeof obj);
+  }
+
+  // Step 5. Let nextMethod be ? GetV(iterator, "next").
+  var nextMethod = iterator.next;
+
+  // Step 6. Let iteratorRecord be the Record { [[Iterator]]: iterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
+  var iteratorRecord = {
+    __proto__: null,
+    iterator,
+    nextMethod,
+    done: false,
+  };
+
+  // Step 7. Return iteratorRecord.
+  return iteratorRecord;
+}
+
+/**
+ * GetIteratorFlattenable ( obj, stringHandling )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-getiteratorflattenable
+ */
+function GetIteratorFlattenable(obj, rejectStrings) {
+  assert(typeof rejectStrings === "boolean", "rejectStrings is a boolean");
+
+  // Step 1.
+  if (!IsObject(obj)) {
+    // Step 1.a.
+    if (rejectStrings || typeof obj !== "string") {
+      ThrowTypeError(JSMSG_OBJECT_REQUIRED, obj === null ? "null" : typeof obj);
+    }
+  }
+
+  // Step 2.
+  var method = obj[GetBuiltinSymbol("iterator")];
+
+  // Steps 3-4.
+  var iterator;
+  if (IsNullOrUndefined(method)) {
+    iterator = obj;
+  } else {
+    iterator = callContentFunction(method, obj);
+  }
+
+  // Step 5.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 6. (Caller must call GetIteratorDirect.)
+  return iterator;
+}
+
+/**
+ * Iterator.from ( O )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iterator.from
+ */
+function IteratorFrom(O) {
+  // Step 1. (Inlined call to GetIteratorDirect.)
+  var iterator = GetIteratorFlattenable(O, /* rejectStrings= */ false);
+  var nextMethod = iterator.next;
+
+  // Step 2.
+  //
+  // Calls |isPrototypeOf| instead of |instanceof| to avoid looking up the
+  // `@@hasInstance` property.
+  var hasInstance = callFunction(
+    std_Object_isPrototypeOf,
+    GetBuiltinPrototype("Iterator"),
+    iterator
+  );
+
+  // Step 3.
+  if (hasInstance) {
+    return iterator;
+  }
+
+  // Step 4.
+  var wrapper = NewWrapForValidIterator();
+
+  // Step 5.
+  UnsafeSetReservedSlot(
+    wrapper,
+    WRAP_FOR_VALID_ITERATOR_ITERATOR_SLOT,
+    iterator
+  );
+  UnsafeSetReservedSlot(
+    wrapper,
+    WRAP_FOR_VALID_ITERATOR_NEXT_METHOD_SLOT,
+    nextMethod
+  );
+
+  // Step 6.
+  return wrapper;
+}
+
+/**
+ * %WrapForValidIteratorPrototype%.next ( )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-wrapforvaliditeratorprototype.next
+ */
+function WrapForValidIteratorNext() {
+  // Steps 1-2.
+  var O = this;
+  if (!IsObject(O) || (O = GuardToWrapForValidIterator(O)) === null) {
+    return callFunction(
+      CallWrapForValidIteratorMethodIfWrapped,
+      this,
+      "WrapForValidIteratorNext"
+    );
+  }
+
+  // Step 3.
+  var iterator = UnsafeGetReservedSlot(O, WRAP_FOR_VALID_ITERATOR_ITERATOR_SLOT);
+  var nextMethod = UnsafeGetReservedSlot(O, WRAP_FOR_VALID_ITERATOR_NEXT_METHOD_SLOT);
+
+  // Step 4.
+  return callContentFunction(nextMethod, iterator);
+}
+
+/**
+ * %WrapForValidIteratorPrototype%.return ( )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-wrapforvaliditeratorprototype.return
+ */
+function WrapForValidIteratorReturn() {
+  // Steps 1-2.
+  var O = this;
+  if (!IsObject(O) || (O = GuardToWrapForValidIterator(O)) === null) {
+    return callFunction(
+      CallWrapForValidIteratorMethodIfWrapped,
+      this,
+      "WrapForValidIteratorReturn"
+    );
+  }
+
+  // Step 3.
+  var iterator = UnsafeGetReservedSlot(O, WRAP_FOR_VALID_ITERATOR_ITERATOR_SLOT);
+
+  // Step 4.
+  assert(IsObject(iterator), "iterator is an object");
+
+  // Step 5.
+  var returnMethod = iterator.return;
+
+  // Step 6.
+  if (IsNullOrUndefined(returnMethod)) {
+    return {
+      value: undefined,
+      done: true,
+    };
+  }
+
+  // Step 7.
+  return callContentFunction(returnMethod, iterator);
+}
+
+/**
+ * %IteratorHelperPrototype%.next ( )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-%iteratorhelperprototype%.next
+ */
+function IteratorHelperNext() {
+  // Step 1.
+  var O = this;
+  if (!IsObject(O) || (O = GuardToIteratorHelper(O)) === null) {
+    return callFunction(
+      CallIteratorHelperMethodIfWrapped,
+      this,
+      "IteratorHelperNext"
+    );
+  }
+  var generator = UnsafeGetReservedSlot(O, ITERATOR_HELPER_GENERATOR_SLOT);
+  return callFunction(GeneratorNext, generator, undefined);
+}
+
+/**
+ * %IteratorHelperPrototype%.return ( )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-%iteratorhelperprototype%.return
+ */
+function IteratorHelperReturn() {
+  // Step 1.
+  var O = this;
+
+  // Step 2.
+  if (!IsObject(O) || (O = GuardToIteratorHelper(O)) === null) {
+    return callFunction(
+      CallIteratorHelperMethodIfWrapped,
+      this,
+      "IteratorHelperReturn"
+    );
+  }
+
+  // Step 3. (Implicit)
+
+  // Steps 4-6.
+  var generator = UnsafeGetReservedSlot(O, ITERATOR_HELPER_GENERATOR_SLOT);
+  return callFunction(GeneratorReturn, generator, undefined);
+}
+
+// Lazy %Iterator.prototype% methods
+//
+// In order to match the semantics of the built-in generator objects used in
+// the proposal, we use a reserved slot on the IteratorHelper objects to store
+// a regular generator that is called from the %IteratorHelper.prototype%
+// methods.
+//
+// Each of the lazy methods is divided into a prelude and a body, with the
+// eager prelude steps being contained in the corresponding IteratorX method
+// and the lazy body steps inside the IteratorXGenerator generator functions.
+//
+// Each prelude method initializes and returns a new IteratorHelper object.
+// As part of this initialization process, the appropriate generator function
+// is called, followed by GeneratorNext being called on returned generator
+// instance in order to move it to its first yield point. This is done so that
+// if the `return` method is called on the IteratorHelper before `next` has been
+// called, we can catch them in the try and use the finally block to close the
+// underlying iterator.
+
+/**
+ * Iterator.prototype.map ( mapper )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.map
+ */
+function IteratorMap(mapper) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3.
+  if (!IsCallable(mapper)) {
+    ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, mapper));
+  }
+
+  // Step 4. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Steps 5-7.
+  var result = NewIteratorHelper();
+  var generator = IteratorMapGenerator(iterator, nextMethod, mapper);
+  UnsafeSetReservedSlot(
+    result,
+    ITERATOR_HELPER_GENERATOR_SLOT,
+    generator
+  );
+
+  // Stop at the initial yield point.
+  callFunction(GeneratorNext, generator);
+
+  // Step 8.
+  return result;
+}
+
+/**
+ * Iterator.prototype.map ( mapper )
+ *
+ * Abstract closure definition.
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.map
+ */
+function* IteratorMapGenerator(iterator, nextMethod, mapper) {
+  var isReturnCompletion = true;
+  try {
+    // Initial yield point to handle closing the iterator before the for-of
+    // loop has been entered for the first time.
+    yield;
+
+    // Not a Return completion when execution continues normally after |yield|.
+    isReturnCompletion = false;
+  } finally {
+    // Call IteratorClose on a Return completion.
+    if (isReturnCompletion) {
+      IteratorClose(iterator);
+    }
+  }
+
+  // Step 5.a.
+  var counter = 0;
+
+  // Step 5.b.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Steps 5.b.i-iii. (Implicit through for-of loop)
+
+    // Step 5.b.iv.
+    var mapped = callContentFunction(mapper, undefined, value, counter);
+
+    // Step 5.b.v. (Implicit through for-of loop)
+
+    // Step 5.b.vi.
+    yield mapped;
+
+    // Step 5.b.vii. (Implicit through for-of loop)
+
+    // Step 5.b.viii.
+    counter += 1;
+  }
+}
+
+/**
+ * Iterator.prototype.filter ( predicate )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.filter
+ */
+function IteratorFilter(predicate) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3.
+  if (!IsCallable(predicate)) {
+    ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, predicate));
+  }
+
+  // Step 4. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Steps 5-7.
+  var result = NewIteratorHelper();
+  var generator = IteratorFilterGenerator(iterator, nextMethod, predicate);
+  UnsafeSetReservedSlot(
+    result,
+    ITERATOR_HELPER_GENERATOR_SLOT,
+    generator
+  );
+
+  // Stop at the initial yield point.
+  callFunction(GeneratorNext, generator);
+
+  // Step 8.
+  return result;
+}
+
+/**
+ * Iterator.prototype.filter ( predicate )
+ *
+ * Abstract closure definition.
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.filter
+ */
+function* IteratorFilterGenerator(iterator, nextMethod, predicate) {
+  var isReturnCompletion = true;
+  try {
+    // Initial yield point to handle closing the iterator before the for-of
+    // loop has been entered for the first time.
+    yield;
+
+    // Not a Return completion when execution continues normally after |yield|.
+    isReturnCompletion = false;
+  } finally {
+    // Call IteratorClose on a Return completion.
+    if (isReturnCompletion) {
+      IteratorClose(iterator);
+    }
+  }
+
+  // Step 5.a.
+  var counter = 0;
+
+  // Step 5.b.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Steps 5.b.i-iii. (Implicit through for-of loop)
+
+    // Step 5.b.iv.
+    var selected = callContentFunction(predicate, undefined, value, counter);
+
+    // Step 5.b.v. (Implicit through for-of loop)
+
+    // Step 5.b.vi.
+    if (selected) {
+      // Step 5.b.vi.1.
+      yield value;
+
+      // Step 5.b.vi.2. (Implicit through for-of loop)
+    }
+
+    // Step 5.b.vii.
+    counter += 1;
+  }
+}
+
+/**
+ * Iterator.prototype.take ( limit )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.take
+ */
+function IteratorTake(limit) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Steps 3-6.
+  var integerLimit = std_Math_trunc(limit);
+  if (!(integerLimit >= 0)) {
+    ThrowRangeError(JSMSG_NEGATIVE_LIMIT);
+  }
+
+  // Step 7. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Steps 8-10.
+  var result = NewIteratorHelper();
+  var generator = IteratorTakeGenerator(iterator, nextMethod, integerLimit);
+  UnsafeSetReservedSlot(
+    result,
+    ITERATOR_HELPER_GENERATOR_SLOT,
+    generator
+  );
+
+  // Stop at the initial yield point.
+  callFunction(GeneratorNext, generator);
+
+  // Step 11.
+  return result;
+}
+
+/**
+ * Iterator.prototype.take ( limit )
+ *
+ * Abstract closure definition.
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.take
+ */
+function* IteratorTakeGenerator(iterator, nextMethod, remaining) {
+  var isReturnCompletion = true;
+  try {
+    // Initial yield point to handle closing the iterator before the for-of
+    // loop has been entered for the first time.
+    yield;
+
+    // Not a Return completion when execution continues normally after |yield|.
+    isReturnCompletion = false;
+  } finally {
+    // Call IteratorClose on a Return completion.
+    if (isReturnCompletion) {
+      IteratorClose(iterator);
+    }
+  }
+
+  // Step 8.a. (Implicit)
+
+  // Step 8.b.i. (Reordered before for-of loop entry)
+  if (remaining === 0) {
+    IteratorClose(iterator);
+    return;
+  }
+
+  // Step 8.b.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Steps 8.b.iii-iv. (Implicit through for-of loop)
+
+    // Step 8.b.v.
+    yield value;
+
+    // Step 8.b.vi. (Implicit through for-of loop)
+
+    // Steps 8.b.i-ii. (Reordered)
+    if (--remaining === 0) {
+      // |break| implicitly calls IteratorClose.
+      break;
+    }
+  }
+}
+
+/**
+ * Iterator.prototype.drop ( limit )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.drop
+ */
+function IteratorDrop(limit) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Steps 3-6.
+  var integerLimit = std_Math_trunc(limit);
+  if (!(integerLimit >= 0)) {
+    ThrowRangeError(JSMSG_NEGATIVE_LIMIT);
+  }
+
+  // Step 7. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Steps 8-10.
+  var result = NewIteratorHelper();
+  var generator = IteratorDropGenerator(iterator, nextMethod, integerLimit);
+  UnsafeSetReservedSlot(
+    result,
+    ITERATOR_HELPER_GENERATOR_SLOT,
+    generator
+  );
+
+  // Stop at the initial yield point.
+  callFunction(GeneratorNext, generator);
+
+  // Step 11.
+  return result;
+}
+
+/**
+ * Iterator.prototype.drop ( limit )
+ *
+ * Abstract closure definition.
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.drop
+ */
+function* IteratorDropGenerator(iterator, nextMethod, remaining) {
+  var isReturnCompletion = true;
+  try {
+    // Initial yield point to handle closing the iterator before the for-of
+    // loop has been entered for the first time.
+    yield;
+
+    // Not a Return completion when execution continues normally after |yield|.
+    isReturnCompletion = false;
+  } finally {
+    // Call IteratorClose on a Return completion.
+    if (isReturnCompletion) {
+      IteratorClose(iterator);
+    }
+  }
+
+  // Step 8.a. (Implicit)
+
+  // Steps 8.b-c.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Step 8.b.i.
+    if (remaining-- <= 0) {
+      // Steps 8.b.ii-iii. (Implicit through for-of loop)
+      // Steps 8.c.i-ii. (Implicit through for-of loop)
+
+      // Step 8.c.iii.
+      yield value;
+
+      // Step 8.c.iv. (Implicit through for-of loop)
+    }
+  }
+}
+
+/**
+ * Iterator.prototype.flatMap ( mapper )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.flatmap
+ */
+function IteratorFlatMap(mapper) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3.
+  if (!IsCallable(mapper)) {
+    ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, mapper));
+  }
+
+  // Step 4. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Steps 5-7.
+  var result = NewIteratorHelper();
+  var generator = IteratorFlatMapGenerator(iterator, nextMethod, mapper);
+  UnsafeSetReservedSlot(
+    result,
+    ITERATOR_HELPER_GENERATOR_SLOT,
+    generator
+  );
+
+  // Stop at the initial yield point.
+  callFunction(GeneratorNext, generator);
+
+  // Step 8.
+  return result;
+}
+
+/**
+ * Iterator.prototype.flatMap ( mapper )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.flatmap
+ */
+function* IteratorFlatMapGenerator(iterator, nextMethod, mapper) {
+  var isReturnCompletion = true;
+  try {
+    // Initial yield point to handle closing the iterator before the for-of
+    // loop has been entered for the first time.
+    yield;
+
+    // Not a Return completion when execution continues normally after |yield|.
+    isReturnCompletion = false;
+  } finally {
+    // Call IteratorClose on a Return completion.
+    if (isReturnCompletion) {
+      IteratorClose(iterator);
+    }
+  }
+
+  // Step 5.a.
+  var counter = 0;
+
+  // Step 5.b.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Steps 5.b.i-iii. (Implicit through for-of loop)
+
+    // Step 5.b.iv.
+    var mapped = callContentFunction(mapper, undefined, value, counter);
+
+    // Step 5.b.v. (Implicit through for-of loop)
+
+    // Steps 5.b.vi.
+    var innerIterator = GetIteratorFlattenable(mapped, /* rejectStrings= */ true);
+    var innerIteratorNextMethod = innerIterator.next;
+
+    // Step 5.b.vii. (Implicit through for-of loop)
+
+    // Steps 5.b.viii-ix.
+    for (var innerValue of allowContentIterWithNext(innerIterator, innerIteratorNextMethod)) {
+      // Steps 5.b.ix.1-3 and 5.b.ix.4.a-b. (Implicit through for-of loop)
+
+      // Step 5.b.ix.4.c.
+      yield innerValue;
+
+      // Step 5.b.ix.4.d. (Implicit through for-of loop)
+    }
+
+    // Step 5.b.x.
+    counter += 1;
+  }
+}
+
+/**
+ * Iterator.prototype.reduce ( reducer [ , initialValue ] )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.reduce
+ */
+function IteratorReduce(reducer /*, initialValue*/) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3.
+  if (!IsCallable(reducer)) {
+    ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, reducer));
+  }
+
+  // Step 4. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Steps 5-6.
+  var accumulator;
+  var counter;
+  if (ArgumentsLength() === 1) {
+    // Steps 5.a-d. (Moved below.)
+    counter = -1;
+  } else {
+    // Step 6.a.
+    accumulator = GetArgument(1);
+
+    // Step 6.b.
+    counter = 0;
+  }
+
+  // Step 7.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    if (counter < 0) {
+      // Step 5. (Reordered steps to compute initial accumulator.)
+
+      // Step 5.c.
+      accumulator = value;
+
+      // Step 5.d.
+      counter = 1;
+    } else {
+      // Steps 7.a-c and 7.e. (Implicit through for-of loop)
+
+      // Steps 7.d and 7.f-g.
+      accumulator = callContentFunction(reducer, undefined, accumulator, value, counter++);
+    }
+  }
+
+  // Step 5.b.
+  if (counter < 0) {
+    ThrowTypeError(JSMSG_EMPTY_ITERATOR_REDUCE);
+  }
+
+  // Step 7.b.
+  return accumulator;
+}
+
+/**
+ * Iterator.prototype.toArray ( )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.toarray
+ */
+function IteratorToArray() {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Steps 4-5.
+  return [...allowContentIterWithNext(iterator, nextMethod)];
+}
+
+/**
+ * Iterator.prototype.forEach ( fn )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.foreach
+ */
+function IteratorForEach(fn) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3.
+  if (!IsCallable(fn)) {
+    ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, fn));
+  }
+
+  // Step 4. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Step 5.
+  var counter = 0;
+
+  // Step 6.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Steps 6.a-c. (Implicit through for-of loop)
+
+    // Steps 6.d and 6.f.
+    callContentFunction(fn, undefined, value, counter++);
+
+    // Step 6.e. (Implicit through for-of loop)
+  }
+}
+
+/**
+ * Iterator.prototype.some ( predicate )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.some
+ */
+function IteratorSome(predicate) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3.
+  if (!IsCallable(predicate)) {
+    ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, predicate));
+  }
+
+  // Step 4. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Step 5.
+  var counter = 0;
+
+  // Step 6.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Steps 6.a-c. (Implicit through for-of loop)
+
+    // Steps 6.d-g.
+    if (callContentFunction(predicate, undefined, value, counter++)) {
+      return true;
+    }
+  }
+
+  // Step 6.b.
+  return false;
+}
+
+/**
+ * Iterator.prototype.every ( predicate )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.every
+ */
+function IteratorEvery(predicate) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3.
+  if (!IsCallable(predicate)) {
+    ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, predicate));
+  }
+
+  // Step 4. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Step 5.
+  var counter = 0;
+
+  // Step 6.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Steps 6.a-c. (Implicit through for-of loop)
+
+    // Steps 6.d-g.
+    if (!callContentFunction(predicate, undefined, value, counter++)) {
+      return false;
+    }
+  }
+
+  // Step 6.b.
+  return true;
+}
+
+/**
+ * Iterator.prototype.find ( predicate )
+ *
+ * https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.find
+ */
+function IteratorFind(predicate) {
+  // Step 1.
+  var iterator = this;
+
+  // Step 2.
+  if (!IsObject(iterator)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, iterator === null ? "null" : typeof iterator);
+  }
+
+  // Step 3.
+  if (!IsCallable(predicate)) {
+    ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, predicate));
+  }
+
+  // Step 4. (Inlined call to GetIteratorDirect.)
+  var nextMethod = iterator.next;
+
+  // Step 5.
+  var counter = 0;
+
+  // Step 6.
+  for (var value of allowContentIterWithNext(iterator, nextMethod)) {
+    // Steps 6.a-c. (Implicit through for-of loop)
+
+    // Steps 6.d-g.
+    if (callContentFunction(predicate, undefined, value, counter++)) {
+      return value;
+    }
+  }
+}