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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 {
macro TryFastStringCompareSequence(
string: String, searchStr: String, start: uintptr,
searchLength: uintptr): Boolean labels Slow {
const directString = Cast<DirectString>(string) otherwise Slow;
const directSearchStr = Cast<DirectString>(searchStr) otherwise Slow;
let searchIndex: uintptr = 0;
let stringIndex: uintptr = start;
while (searchIndex < searchLength) {
if (StringCharCodeAt(directSearchStr, searchIndex) !=
StringCharCodeAt(directString, stringIndex)) {
return False;
}
searchIndex++;
stringIndex++;
}
return True;
}
// https://tc39.github.io/ecma262/#sec-string.prototype.endswith
transitioning javascript builtin StringPrototypeEndsWith(
js-implicit context: NativeContext,
receiver: JSAny)(...arguments): Boolean {
const searchString: JSAny = arguments[0];
const endPosition: JSAny = arguments[1];
const kBuiltinName: constexpr string = 'String.prototype.endsWith';
// 1. Let O be ? RequireObjectCoercible(this value).
// 2. Let S be ? ToString(O).
const string: String = ToThisString(receiver, kBuiltinName);
// 3. Let isRegExp be ? IsRegExp(searchString).
// 4. If isRegExp is true, throw a TypeError exception.
if (regexp::IsRegExp(searchString)) {
ThrowTypeError(MessageTemplate::kFirstArgumentNotRegExp, kBuiltinName);
}
// 5. Let searchStr be ? ToString(searchString).
const searchStr: String = ToString_Inline(searchString);
// 6. Let len be the length of S.
const len: uintptr = string.length_uintptr;
// 7. If endPosition is undefined, let pos be len,
// else let pos be ? ToInteger(endPosition).
// 8. Let end be min(max(pos, 0), len).
const end: uintptr =
(endPosition != Undefined) ? ClampToIndexRange(endPosition, len) : len;
// 9. Let searchLength be the length of searchStr.
const searchLength: uintptr = searchStr.length_uintptr;
// 10. Let start be end - searchLength.
const start: uintptr = end - searchLength;
// 11. If start is less than 0, return false.
if (Signed(start) < 0) return False;
// 12. If the sequence of code units of S starting at start of length
// searchLength is the same as the full code unit sequence of searchStr,
// return true.
// 13. Otherwise, return false.
try {
// Fast Path: If both strings are direct and relevant indices are Smis.
return TryFastStringCompareSequence(
string, searchStr, start, searchLength) otherwise Slow;
}
label Slow {
// Slow Path: If either of the string is indirect, bail into runtime.
return StringCompareSequence(
context, string, searchStr, Convert<Number>(start));
}
}
}
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