From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 02:47:55 +0200 Subject: Adding upstream version 124.0.1. Signed-off-by: Daniel Baumann --- js/public/ForOfIterator.h | 118 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 js/public/ForOfIterator.h (limited to 'js/public/ForOfIterator.h') diff --git a/js/public/ForOfIterator.h b/js/public/ForOfIterator.h new file mode 100644 index 0000000000..db0a099e5e --- /dev/null +++ b/js/public/ForOfIterator.h @@ -0,0 +1,118 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/* + * A convenience class that makes it easy to perform the operations of a for-of + * loop. + */ + +#ifndef js_ForOfIterator_h +#define js_ForOfIterator_h + +#include "mozilla/Attributes.h" // MOZ_STACK_CLASS + +#include // UINT32_MAX, uint32_t + +#include "jstypes.h" // JS_PUBLIC_API + +#include "js/RootingAPI.h" // JS::{Handle,Rooted} +#include "js/Value.h" // JS::Value, JS::{,Mutable}Handle + +struct JS_PUBLIC_API JSContext; +class JS_PUBLIC_API JSObject; + +namespace JS { + +/** + * A convenience class for imitating a JS for-of loop. Typical usage: + * + * JS::ForOfIterator it(cx); + * if (!it.init(iterable)) { + * return false; + * } + * JS::Rooted val(cx); + * while (true) { + * bool done; + * if (!it.next(&val, &done)) { + * return false; + * } + * if (done) { + * break; + * } + * if (!DoStuff(cx, val)) { + * return false; + * } + * } + */ +class MOZ_STACK_CLASS JS_PUBLIC_API ForOfIterator { + protected: + JSContext* cx_; + + // Use the ForOfPIC on the global object (see vm/GlobalObject.h) to try to + // optimize iteration across arrays. + // + // Case 1: Regular Iteration + // iterator - pointer to the iterator object. + // nextMethod - value of |iterator|.next. + // index - fixed to NOT_ARRAY (== UINT32_MAX) + // + // Case 2: Optimized Array Iteration + // iterator - pointer to the array object. + // nextMethod - the undefined value. + // index - current position in array. + // + // The cases are distinguished by whether |index == NOT_ARRAY|. + Rooted iterator; + Rooted nextMethod; + + static constexpr uint32_t NOT_ARRAY = UINT32_MAX; + + uint32_t index = NOT_ARRAY; + + ForOfIterator(const ForOfIterator&) = delete; + ForOfIterator& operator=(const ForOfIterator&) = delete; + + public: + explicit ForOfIterator(JSContext* cx) + : cx_(cx), iterator(cx), nextMethod(cx) {} + + enum NonIterableBehavior { ThrowOnNonIterable, AllowNonIterable }; + + /** + * Initialize the iterator. If AllowNonIterable is passed then if getting + * the @@iterator property from iterable returns undefined init() will just + * return true instead of throwing. Callers must then check + * valueIsIterable() before continuing with the iteration. + */ + [[nodiscard]] bool init( + Handle iterable, + NonIterableBehavior nonIterableBehavior = ThrowOnNonIterable); + + /** + * Get the next value from the iterator. If false *done is true + * after this call, do not examine val. + */ + [[nodiscard]] bool next(MutableHandle val, bool* done); + + /** + * Close the iterator. + * For the case that completion type is throw. + */ + void closeThrow(); + + /** + * If initialized with throwOnNonCallable = false, check whether + * the value is iterable. + */ + bool valueIsIterable() const { return iterator; } + + private: + inline bool nextFromOptimizedArray(MutableHandle val, bool* done); +}; + +} // namespace JS + +#endif // js_ForOfIterator_h -- cgit v1.2.3