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// Copyright 2019 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 string {
const kBuiltinName: constexpr string = 'String.prototype.repeat';
builtin StringRepeat(implicit context: Context)(
string: String, count: Smi): String {
dcheck(count >= 0);
dcheck(string != kEmptyString);
let result: String = kEmptyString;
let powerOfTwoRepeats: String = string;
let n: intptr = Convert<intptr>(count);
while (true) {
if ((n & 1) == 1) result = result + powerOfTwoRepeats;
n = n >> 1;
if (n == 0) break;
powerOfTwoRepeats = powerOfTwoRepeats + powerOfTwoRepeats;
}
return result;
}
// https://tc39.github.io/ecma262/#sec-string.prototype.repeat
transitioning javascript builtin StringPrototypeRepeat(
js-implicit context: NativeContext, receiver: JSAny)(count: JSAny): String {
// 1. Let O be ? RequireObjectCoercible(this value).
// 2. Let S be ? ToString(O).
const s: String = ToThisString(receiver, kBuiltinName);
try {
// 3. Let n be ? ToInteger(count).
typeswitch (ToInteger_Inline(count)) {
case (n: Smi): {
// 4. If n < 0, throw a RangeError exception.
if (n < 0) goto InvalidCount;
// 6. If n is 0, return the empty String.
if (n == 0 || s.length_uint32 == 0) goto EmptyString;
if (n > kStringMaxLength) goto InvalidStringLength;
// 7. Return the String value that is made from n copies of S appended
// together.
return StringRepeat(s, n);
}
case (heapNum: HeapNumber): deferred {
dcheck(IsNumberNormalized(heapNum));
const n = LoadHeapNumberValue(heapNum);
// 4. If n < 0, throw a RangeError exception.
// 5. If n is +∞, throw a RangeError exception.
if (n == V8_INFINITY || n < 0) goto InvalidCount;
// 6. If n is 0, return the empty String.
if (s.length_uint32 == 0) goto EmptyString;
goto InvalidStringLength;
}
}
} label EmptyString {
return kEmptyString;
} label InvalidCount deferred {
ThrowRangeError(MessageTemplate::kInvalidCountValue, count);
} label InvalidStringLength deferred {
ThrowInvalidStringLength(context);
}
}
}
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