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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.
// TODO(turbofan): This could be replaced with a fast C-call to
// CompareCharsUnsigned.
macro IsSubstringAt<A: type, B: type>(
string: ConstSlice<A>, searchStr: ConstSlice<B>, start: intptr): bool {
const subslice =
Subslice(string, start, searchStr.length) otherwise return false;
let stringIterator = subslice.Iterator();
let searchIterator = searchStr.Iterator();
while (true) {
const searchChar = searchIterator.Next() otherwise return true;
const stringChar = stringIterator.Next() otherwise unreachable;
if (searchChar != stringChar) {
return false;
}
}
VerifiedUnreachable();
}
struct IsSubstringAtFunctor {
start: intptr;
}
// Ideally, this would be a method of IsSubstringAtFunctor, but currently
// methods don't support templates.
macro Call<A: type, B: type>(
self: IsSubstringAtFunctor, string: ConstSlice<A>,
searchStr: ConstSlice<B>): bool {
return IsSubstringAt(string, searchStr, self.start);
}
macro IsSubstringAt(string: String, searchStr: String, start: intptr): bool {
return TwoStringsToSlices<bool>(
string, searchStr, IsSubstringAtFunctor{start: start});
}
// 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 = Signed(end - searchLength);
// 11. If start is less than 0, return false.
if (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.
return Convert<Boolean>(IsSubstringAt(string, searchStr, start));
}
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