Function At

deps/v8/test/mjsunit/typedarray-resizablearraybuffer.js:1455–1510

(atHelper, oobThrows)

})();

function At(atHelper, oobThrows) {
  for (let ctor of ctors) {
    const rab = CreateResizableArrayBuffer(4 * ctor.BYTES_PER_ELEMENT,
                                           8 * ctor.BYTES_PER_ELEMENT);
    const fixedLength = new ctor(rab, 0, 4);
    const fixedLengthWithOffset = new ctor(rab, 2 * ctor.BYTES_PER_ELEMENT, 2);
    const lengthTracking = new ctor(rab, 0);
    const lengthTrackingWithOffset = new ctor(rab, 2 * ctor.BYTES_PER_ELEMENT);

    // Write some data into the array.
    let ta_write = new ctor(rab);
    for (let i = 0; i < 4; ++i) {
      WriteToTypedArray(ta_write, i, i);
    }

    assertEquals(3, atHelper(fixedLength, -1));
    assertEquals(3, atHelper(lengthTracking, -1));
    assertEquals(3, atHelper(fixedLengthWithOffset, -1));
    assertEquals(3, atHelper(lengthTrackingWithOffset, -1));

    // Shrink so that fixed length TAs go out of bounds.
    rab.resize(3 * ctor.BYTES_PER_ELEMENT);

    if (oobThrows) {
      assertThrows(() => { atHelper(fixedLength, -1); });
      assertThrows(() => { atHelper(fixedLengthWithOffset, -1); });
    } else {
      assertEquals(undefined, atHelper(fixedLength, -1));
      assertEquals(undefined, atHelper(fixedLengthWithOffset, -1));
    }

    assertEquals(2, atHelper(lengthTracking, -1));
    assertEquals(2, atHelper(lengthTrackingWithOffset, -1));

    // Shrink so that the TAs with offset go out of bounds.
    rab.resize(1 * ctor.BYTES_PER_ELEMENT);

    if (oobThrows) {
      assertThrows(() => { atHelper(fixedLength, -1); });
      assertThrows(() => { atHelper(fixedLengthWithOffset, -1); });
      assertThrows(() => { atHelper(lengthTrackingWithOffset, -1); });
    } else {
      assertEquals(undefined, atHelper(fixedLength, -1));
      assertEquals(undefined, atHelper(fixedLengthWithOffset, -1));
      assertEquals(undefined, atHelper(lengthTrackingWithOffset, -1));
    }
    assertEquals(0, atHelper(lengthTracking, -1));

    // Grow so that all TAs are back in-bounds. New memory is zeroed.
    rab.resize(6 * ctor.BYTES_PER_ELEMENT);
    assertEquals(0, atHelper(fixedLength, -1));
    assertEquals(0, atHelper(lengthTracking, -1));
    assertEquals(0, atHelper(fixedLengthWithOffset, -1));
    assertEquals(0, atHelper(lengthTrackingWithOffset, -1));
  }
}
At(TypedArrayAtHelper, true);
At(ArrayAtHelper, false);