// 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)); } } }