| // Copyright 2018 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. |
| |
| #include 'src/builtins/builtins-regexp-gen.h' |
| |
| namespace string { |
| extern macro RegExpBuiltinsAssembler::IsRegExp(implicit context: |
| Context)(Object): bool; |
| |
| // https://tc39.github.io/ecma262/#sec-string.prototype.startswith |
| transitioning javascript builtin StringPrototypeStartsWith( |
| js-implicit context: Context, receiver: Object)(...arguments): Boolean { |
| const searchString: Object = arguments[0]; |
| const position: Object = arguments[1]; |
| const kBuiltinName: constexpr string = 'String.prototype.startsWith'; |
| |
| // 1. Let O be ? RequireObjectCoercible(this value). |
| const object: Object = RequireObjectCoercible(receiver, kBuiltinName); |
| |
| // 2. Let S be ? ToString(O). |
| const string: String = ToString_Inline(context, object); |
| |
| // 3. Let isRegExp be ? IsRegExp(searchString). |
| // 4. If isRegExp is true, throw a TypeError exception. |
| if (IsRegExp(searchString)) { |
| ThrowTypeError(kFirstArgumentNotRegExp, kBuiltinName); |
| } |
| |
| // 5. Let searchStr be ? ToString(searchString). |
| const searchStr: String = ToString_Inline(context, searchString); |
| |
| // 6. Let pos be ? ToInteger(position). |
| const pos: Number = ToInteger_Inline(context, position); |
| |
| // 7. Assert: If position is undefined, then pos is 0. |
| // 8. Let len be the length of S. |
| const len: Number = string.length_smi; |
| |
| // 9. Let start be min(max(pos, 0), len). |
| const start: Number = NumberMin(NumberMax(pos, 0), len); |
| |
| // 10. Let searchLength be the length of searchStr. |
| const searchLength: Smi = searchStr.length_smi; |
| |
| // 11. If searchLength + start is greater than len, return false. |
| if (searchLength + start > len) 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, start); |
| } |
| } |
| } |