forked from mirrors/gecko-dev
57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_dom_StreamUtils_h
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#define mozilla_dom_StreamUtils_h
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#include "mozilla/ErrorResult.h"
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#include "mozilla/dom/Promise.h"
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class nsIGlobalObject;
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namespace mozilla::dom {
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struct QueuingStrategy;
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double ExtractHighWaterMark(const QueuingStrategy& aStrategy,
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double aDefaultHWM, ErrorResult& aRv);
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// Promisification algorithm, shared among:
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// Step 2 and 3 of https://streams.spec.whatwg.org/#readablestream-set-up
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// Step 2 and 3 of
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// https://streams.spec.whatwg.org/#readablestream-set-up-with-byte-reading-support
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// Step 2 and 3 of https://streams.spec.whatwg.org/#writablestream-set-up
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// Step 5 and 6 of https://streams.spec.whatwg.org/#transformstream-set-up
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template <typename T>
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MOZ_CAN_RUN_SCRIPT static already_AddRefed<Promise> PromisifyAlgorithm(
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nsIGlobalObject* aGlobal, T aFunc, mozilla::ErrorResult& aRv) {
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// Step 1. Let result be the result of running (algorithm). If this throws an
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// exception e, return a promise rejected with e.
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RefPtr<Promise> result;
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if constexpr (!std::is_same<decltype(aFunc(aRv)), void>::value) {
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result = aFunc(aRv);
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} else {
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aFunc(aRv);
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}
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if (aRv.IsUncatchableException()) {
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return nullptr;
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}
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if (aRv.Failed()) {
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return Promise::CreateRejectedWithErrorResult(aGlobal, aRv);
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}
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// Step 2. If result is a Promise, then return result.
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if (result) {
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return result.forget();
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}
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// Step 3. Return a promise resolved with undefined.
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return Promise::CreateResolvedWithUndefined(aGlobal, aRv);
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}
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} // namespace mozilla::dom
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#endif // mozilla_dom_StreamUtils_h
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