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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 array_copywithin {
macro ConvertToRelativeIndex(index: Number, length: Number): Number {
return index < 0 ? Max(index + length, 0) : Min(index, length);
}
// https://tc39.github.io/ecma262/#sec-array.prototype.copyWithin
transitioning javascript builtin ArrayPrototypeCopyWithin(
js-implicit context: Context, receiver: Object)(...arguments): Object {
// 1. Let O be ? ToObject(this value).
const object: JSReceiver = ToObject_Inline(context, receiver);
// 2. Let len be ? ToLength(? Get(O, "length")).
const length: Number = GetLengthProperty(object);
// 3. Let relativeTarget be ? ToInteger(target).
const relativeTarget: Number = ToInteger_Inline(context, arguments[0]);
// 4. If relativeTarget < 0, let to be max((len + relativeTarget), 0);
// else let to be min(relativeTarget, len).
let to: Number = ConvertToRelativeIndex(relativeTarget, length);
// 5. Let relativeStart be ? ToInteger(start).
const relativeStart: Number = ToInteger_Inline(context, arguments[1]);
// 6. If relativeStart < 0, let from be max((len + relativeStart), 0);
// else let from be min(relativeStart, len).
let from: Number = ConvertToRelativeIndex(relativeStart, length);
// 7. If end is undefined, let relativeEnd be len;
// else let relativeEnd be ? ToInteger(end).
let relativeEnd: Number = length;
if (arguments[2] != Undefined) {
relativeEnd = ToInteger_Inline(context, arguments[2]);
}
// 8. If relativeEnd < 0, let final be max((len + relativeEnd), 0);
// else let final be min(relativeEnd, len).
const final: Number = ConvertToRelativeIndex(relativeEnd, length);
// 9. Let count be min(final-from, len-to).
let count: Number = Min(final - from, length - to);
// 10. If from<to and to<from+count, then.
let direction: Number = 1;
if (from < to && to < (from + count)) {
// a. Let direction be -1.
direction = -1;
// b. Let from be from + count - 1.
from = from + count - 1;
// c. Let to be to + count - 1.
to = to + count - 1;
}
// 12. Repeat, while count > 0.
while (count > 0) {
// a. Let fromKey be ! ToString(from).
// b. Let toKey be ! ToString(to).
// c. Let fromPresent be ? HasProperty(O, fromKey).
const fromPresent: Boolean = HasProperty(object, from);
// d. If fromPresent is true, then.
if (fromPresent == True) {
// i. Let fromVal be ? Get(O, fromKey).
const fromVal: Object = GetProperty(object, from);
// ii. Perform ? Set(O, toKey, fromVal, true).
SetProperty(object, to, fromVal);
} else {
// i. Perform ? DeletePropertyOrThrow(O, toKey).
DeleteProperty(object, to, kStrict);
}
// f. Let from be from + direction.
from = from + direction;
// g. Let to be to + direction.
to = to + direction;
// h. Let count be count - 1.
--count;
}
// 13. Return O.
return object;
}
}
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