dom/streams/CountQueuingStrategy.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/dom/CountQueuingStrategy.h"
   8 #include "mozilla/dom/FunctionBinding.h"
   9 #include "mozilla/dom/QueuingStrategyBinding.h"
  10 #include "nsCOMPtr.h"
  11 #include "nsISupports.h"
  12
  13 namespace mozilla::dom {
  14
  15 NS_IMPL_CYCLE_COLLECTION(BaseQueuingStrategy, mGlobal)
  16 NS_IMPL_CYCLE_COLLECTING_ADDREF(BaseQueuingStrategy)
  17 NS_IMPL_CYCLE_COLLECTING_RELEASE(BaseQueuingStrategy)
  18
  19 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(BaseQueuingStrategy)
  20   NS_INTERFACE_MAP_ENTRY(nsISupports)
  21 NS_INTERFACE_MAP_END
  22
  23 NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_INHERITED(CountQueuingStrategy,
  24                                                 BaseQueuingStrategy)
  25 NS_IMPL_ADDREF_INHERITED(CountQueuingStrategy, BaseQueuingStrategy)
  26 NS_IMPL_RELEASE_INHERITED(CountQueuingStrategy, BaseQueuingStrategy)
  27
  28 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(CountQueuingStrategy)
  29   NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
  30 NS_INTERFACE_MAP_END_INHERITING(BaseQueuingStrategy)
  31
  32 /* static */
  33 already_AddRefed<CountQueuingStrategy> CountQueuingStrategy::Constructor(
  34     const GlobalObject& aGlobal, const QueuingStrategyInit& aInit) {
  35   RefPtr<CountQueuingStrategy> strategy =
  36       new CountQueuingStrategy(aGlobal.GetAsSupports(), aInit.mHighWaterMark);
  37   return strategy.forget();
  38 }
  39
  40 nsIGlobalObject* BaseQueuingStrategy::GetParentObject() const {
  41   return mGlobal;
  42 }
  43
  44 JSObject* CountQueuingStrategy::WrapObject(JSContext* aCx,
  45                                            JS::Handle<JSObject*> aGivenProto) {
  46   return CountQueuingStrategy_Binding::Wrap(aCx, this, aGivenProto);
  47 }
  48
  49 // https://streams.spec.whatwg.org/#count-queuing-strategy-size-function
  50 static bool CountQueuingStrategySize(JSContext* aCx, unsigned aArgc,
  51                                      JS::Value* aVp) {
  52   JS::CallArgs args = CallArgsFromVp(aArgc, aVp);
  53
  54   // Step 1.1. Return 1.
  55   args.rval().setInt32(1);
  56   return true;
  57 }
  58
  59 // https://streams.spec.whatwg.org/#cqs-size
  60 already_AddRefed<Function> CountQueuingStrategy::GetSize(ErrorResult& aRv) {
  61   // Step 1. Return this's relevant global object's count queuing strategy
  62   // size function.
  63   if (RefPtr<Function> fun = mGlobal->GetCountQueuingStrategySizeFunction()) {
  64     return fun.forget();
  65   }
  66
  67   // Note: Instead of eagerly allocating a size function for every global object
  68   // we do it lazily once in this getter.
  69   // After this point the steps refer to:
  70   // https://streams.spec.whatwg.org/#count-queuing-strategy-size-function.
  71
  72   AutoJSAPI jsapi;
  73   if (!jsapi.Init(mGlobal)) {
  74     aRv.ThrowUnknownError("Internal error");
  75     return nullptr;
  76   }
  77   JSContext* cx = jsapi.cx();
  78
  79   // Step 1. Let steps be the following steps:
  80   // Note: See CountQueuingStrategySize instead.
  81
  82   // Step 2. Let F be
  83   // ! CreateBuiltinFunction(steps, 0, "size", « »,
  84   //                         globalObject’s relevant Realm).
  85   JS::Rooted<JSFunction*> sizeFunction(
  86       cx, JS_NewFunction(cx, CountQueuingStrategySize, 0, 0, "size"));
  87   if (!sizeFunction) {
  88     aRv.StealExceptionFromJSContext(cx);
  89     return nullptr;
  90   }
  91
  92   // Step 3. Set globalObject’s count queuing strategy size function to
  93   // a Function that represents a reference to F,
  94   // with callback context equal to globalObject’s relevant settings object.
  95   JS::Rooted<JSObject*> funObj(cx, JS_GetFunctionObject(sizeFunction));
  96   JS::Rooted<JSObject*> global(cx, mGlobal->GetGlobalJSObject());
  97   RefPtr<Function> function = new Function(cx, funObj, global, mGlobal);
  98   mGlobal->SetCountQueuingStrategySizeFunction(function);
  99
 100   return function.forget();
 101 }
 102
 103 }  // namespace mozilla::dom