iterator.tq

// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include 'src/builtins/builtins-iterator-gen.h'

namespace iterator {
// Returned from IteratorBuiltinsAssembler::GetIterator().
@export
struct IteratorRecord {
  // iteratorRecord.[[Iterator]]
  object: JSReceiver;

  // iteratorRecord.[[NextMethod]]
  next: JSAny;
}

extern macro IteratorBuiltinsAssembler::FastIterableToList(
    implicit context: Context)(JSAny): JSArray labels Slow;

extern macro IteratorBuiltinsAssembler::GetIteratorMethod(
    implicit context: Context)(JSAny): JSAny;
extern macro IteratorBuiltinsAssembler::GetIterator(implicit context: Context)(
    JSAny): IteratorRecord;
extern macro IteratorBuiltinsAssembler::GetIterator(implicit context: Context)(
    JSAny, JSAny): IteratorRecord;

extern macro IteratorBuiltinsAssembler::IteratorStep(implicit context: Context)(
    IteratorRecord): JSReceiver
    labels Done;
extern macro IteratorBuiltinsAssembler::IteratorStep(implicit context: Context)(
    IteratorRecord, Map): JSReceiver
    labels Done;

extern macro IteratorBuiltinsAssembler::IteratorValue(
    implicit context: Context)(JSReceiver): JSAny;
extern macro IteratorBuiltinsAssembler::IteratorValue(
    implicit context: Context)(JSReceiver, Map): JSAny;

extern macro IteratorBuiltinsAssembler::IterableToList(
    implicit context: Context)(JSAny, JSAny): JSArray;

extern macro IteratorBuiltinsAssembler::StringListFromIterable(
    implicit context: Context)(JSAny): JSArray;

extern builtin IterableToListWithSymbolLookup(implicit context: Context)(JSAny):
    JSArray;
extern builtin IterableToFixedArrayWithSymbolLookupSlow(
    implicit context: Context)(JSAny): FixedArray;

transitioning builtin GetIteratorWithFeedback(
    context: Context, receiver: JSAny, loadSlot: TaggedIndex,
    callSlot: TaggedIndex, feedback: Undefined|FeedbackVector): JSAny {
  let iteratorMethod: JSAny;
  typeswitch (feedback) {
    case (Undefined): {
      iteratorMethod = GetProperty(receiver, IteratorSymbolConstant());
    }
    case (feedback: FeedbackVector): {
      iteratorMethod = LoadIC(
          context, receiver, IteratorSymbolConstant(), loadSlot, feedback);
    }
  }
  // TODO(v8:10047): Use TaggedIndex here once TurboFan supports it.
  const callSlotSmi: Smi = TaggedIndexToSmi(callSlot);
  return CallIteratorWithFeedback(
      context, receiver, iteratorMethod, callSlotSmi, feedback);
}

transitioning builtin CallIteratorWithFeedback(
    context: Context, receiver: JSAny, iteratorMethod: JSAny, callSlot: Smi,
    feedback: Undefined|FeedbackVector): JSAny {
  const callSlotUnTagged: uintptr = Unsigned(SmiUntag(callSlot));
  ic::CollectCallFeedback(iteratorMethod, context, feedback, callSlotUnTagged);
  const iteratorCallable: Callable = Cast<Callable>(iteratorMethod)
      otherwise ThrowCalledNonCallable(iteratorMethod);
  return Call(context, iteratorCallable, receiver);
}

// https://tc39.es/ecma262/#sec-iteratorclose
@export
transitioning macro IteratorCloseOnException(implicit context: Context)(
    iterator: IteratorRecord) {
  try {
    // 4. Let innerResult be GetMethod(iterator, "return").
    const method = GetProperty(iterator.object, kReturnString);

    // 5. If innerResult.[[Type]] is normal, then
    //   a. Let return be innerResult.[[Value]].
    //   b. If return is undefined, return Completion(completion).
    if (method == Undefined || method == Null) return;

    //   c. Set innerResult to Call(return, iterator).
    // If an exception occurs, the original exception remains bound
    Call(context, method, iterator.object);
  } catch (_e) {
    // Swallow the exception.
  }

  // (If completion.[[Type]] is throw) return Completion(completion).
}
}