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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_slice {
extern macro StringBuiltinsAssembler::SubString(String, intptr, intptr):
String;
// ES6 #sec-string.prototype.slice ( start, end )
// https://tc39.github.io/ecma262/#sec-string.prototype.slice
transitioning javascript builtin StringPrototypeSlice(
js-implicit context: Context, receiver: JSAny)(...arguments): String {
// 1. Let O be ? RequireObjectCoercible(this value).
// 2. Let S be ? ToString(O).
const string: String = ToThisString(receiver, 'String.prototype.slice');
// 3. Let len be the number of elements in S.
const length: intptr = string.length_intptr;
// Convert {start} to a relative index.
const start: intptr = ConvertToRelativeIndex(arguments[0], length);
// 5. If end is undefined, let intEnd be len;
// else Convert {end} to a relative index.
const temp = arguments[1];
const end: intptr =
temp == Undefined ? length : ConvertToRelativeIndex(temp, length);
if (end <= start) {
return kEmptyString;
}
return SubString(string, start, end);
}
}
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