object-fromentries.tq 2.79 KB
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// 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.

namespace object {

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transitioning macro ObjectFromEntriesFastCase(implicit context: Context)(
    iterable: JSAny): JSObject labels IfSlow {
  typeswitch (iterable) {
    case (array: FastJSArrayWithNoCustomIteration): {
      const elements: FixedArray =
          Cast<FixedArray>(array.elements) otherwise IfSlow;
      const length: Smi = array.length;
      const result: JSObject = NewJSObject();
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      for (let k: Smi = 0; k < length; ++k) {
        const value: JSAny = array::LoadElementOrUndefined(elements, k);
        const pair: KeyValuePair =
            collections::LoadKeyValuePairNoSideEffects(value)
            otherwise IfSlow;
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        // CreateDataProperty only handles Names and Numbers. Bail out if
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        // the key is not one of those types. Note that JSReceivers should
        // always bail to the slow path, as calling Symbol.toPrimitive,
        // toString, or valueOf could invalidate assumptions about the
        // iterable.
        typeswitch (pair.key) {
          case (Name): {
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            CreateDataProperty(result, pair.key, pair.value);
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          }
          case (Number): {
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            CreateDataProperty(result, pair.key, pair.value);
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          }
          case (oddball: Oddball): {
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            CreateDataProperty(result, oddball.to_string, pair.value);
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          }
          case (JSAny): {
            goto IfSlow;
          }
        }
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      }
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      return result;
    }
    case (JSAny): {
      goto IfSlow;
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    }
  }
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}
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transitioning javascript builtin
ObjectFromEntries(
    js-implicit context: NativeContext, receiver: JSAny)(...arguments): JSAny {
  const iterable: JSAny = arguments[0];
  try {
    if (IsNullOrUndefined(iterable)) goto Throw;
    return ObjectFromEntriesFastCase(iterable) otherwise IfSlow;
  } label IfSlow {
    const result: JSObject = NewJSObject();
    const fastIteratorResultMap: Map = GetIteratorResultMap();
    let i: iterator::IteratorRecord = iterator::GetIterator(iterable);
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    try {
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      dcheck(!IsNullOrUndefined(i.object));
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      while (true) {
        const step: JSReceiver =
            iterator::IteratorStep(i, fastIteratorResultMap)
            otherwise return result;
        const iteratorValue: JSAny =
            iterator::IteratorValue(step, fastIteratorResultMap);
        const pair: KeyValuePair = collections::LoadKeyValuePair(iteratorValue);
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        CreateDataProperty(result, pair.key, pair.value);
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      }
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      return result;
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    } catch (e, message) deferred {
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      iterator::IteratorCloseOnException(i);
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      ReThrowWithMessage(context, e, message);
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    }
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  } label Throw deferred {
    ThrowTypeError(MessageTemplate::kNotIterable);
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  }
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}
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}  // namespace object