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JSEventHandler.h (6343B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      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 #ifndef mozilla_JSEventHandler_h_
      8 #define mozilla_JSEventHandler_h_
      9 
     10 #include "mozilla/MemoryReporting.h"
     11 #include "mozilla/dom/EventHandlerBinding.h"
     12 #include "nsAtom.h"
     13 #include "nsCOMPtr.h"
     14 #include "nsCycleCollectionParticipant.h"
     15 #include "nsIDOMEventListener.h"
     16 #include "nsIScriptContext.h"
     17 
     18 namespace mozilla {
     19 namespace dom {
     20 class EventTarget;
     21 }  // namespace dom
     22 
     23 class TypedEventHandler {
     24 public:
     25  enum HandlerType {
     26    eUnset = 0,
     27    eNormal = 0x1,
     28    eOnError = 0x2,
     29    eOnBeforeUnload = 0x3,
     30    eTypeBits = 0x3
     31  };
     32 
     33  TypedEventHandler() : mBits(0) {}
     34 
     35  explicit TypedEventHandler(dom::EventHandlerNonNull* aHandler) : mBits(0) {
     36    Assign(aHandler, eNormal);
     37  }
     38 
     39  explicit TypedEventHandler(dom::OnErrorEventHandlerNonNull* aHandler)
     40      : mBits(0) {
     41    Assign(aHandler, eOnError);
     42  }
     43 
     44  explicit TypedEventHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler)
     45      : mBits(0) {
     46    Assign(aHandler, eOnBeforeUnload);
     47  }
     48 
     49  TypedEventHandler(const TypedEventHandler& aOther) {
     50    if (aOther.HasEventHandler()) {
     51      // Have to make sure we take our own ref
     52      Assign(aOther.Ptr(), aOther.Type());
     53    } else {
     54      mBits = 0;
     55    }
     56  }
     57 
     58  ~TypedEventHandler() { ReleaseHandler(); }
     59 
     60  HandlerType Type() const { return HandlerType(mBits & eTypeBits); }
     61 
     62  bool HasEventHandler() const { return !!Ptr(); }
     63 
     64  void SetHandler(const TypedEventHandler& aHandler) {
     65    if (aHandler.HasEventHandler()) {
     66      ReleaseHandler();
     67      Assign(aHandler.Ptr(), aHandler.Type());
     68    } else {
     69      ForgetHandler();
     70    }
     71  }
     72 
     73  dom::EventHandlerNonNull* NormalEventHandler() const {
     74    MOZ_ASSERT(Type() == eNormal && Ptr());
     75    return reinterpret_cast<dom::EventHandlerNonNull*>(Ptr());
     76  }
     77 
     78  void SetHandler(dom::EventHandlerNonNull* aHandler) {
     79    ReleaseHandler();
     80    Assign(aHandler, eNormal);
     81  }
     82 
     83  dom::OnBeforeUnloadEventHandlerNonNull* OnBeforeUnloadEventHandler() const {
     84    MOZ_ASSERT(Type() == eOnBeforeUnload);
     85    return reinterpret_cast<dom::OnBeforeUnloadEventHandlerNonNull*>(Ptr());
     86  }
     87 
     88  void SetHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler) {
     89    ReleaseHandler();
     90    Assign(aHandler, eOnBeforeUnload);
     91  }
     92 
     93  dom::OnErrorEventHandlerNonNull* OnErrorEventHandler() const {
     94    MOZ_ASSERT(Type() == eOnError);
     95    return reinterpret_cast<dom::OnErrorEventHandlerNonNull*>(Ptr());
     96  }
     97 
     98  void SetHandler(dom::OnErrorEventHandlerNonNull* aHandler) {
     99    ReleaseHandler();
    100    Assign(aHandler, eOnError);
    101  }
    102 
    103  dom::CallbackFunction* Ptr() const {
    104    // Have to cast eTypeBits so we don't have to worry about
    105    // promotion issues after the bitflip.
    106    return reinterpret_cast<dom::CallbackFunction*>(mBits &
    107                                                    ~uintptr_t(eTypeBits));
    108  }
    109 
    110  void ForgetHandler() {
    111    ReleaseHandler();
    112    mBits = 0;
    113  }
    114 
    115  bool operator==(const TypedEventHandler& aOther) const {
    116    return Ptr() && aOther.Ptr() &&
    117           Ptr()->CallbackPreserveColor() ==
    118               aOther.Ptr()->CallbackPreserveColor();
    119  }
    120 
    121 private:
    122  void operator=(const TypedEventHandler&) = delete;
    123 
    124  void ReleaseHandler() {
    125    nsISupports* ptr = Ptr();
    126    NS_IF_RELEASE(ptr);
    127  }
    128 
    129  void Assign(nsISupports* aHandler, HandlerType aType) {
    130    MOZ_ASSERT(aHandler, "Must have handler");
    131    NS_ADDREF(aHandler);
    132    mBits = uintptr_t(aHandler) | uintptr_t(aType);
    133  }
    134 
    135  uintptr_t mBits;
    136 };
    137 
    138 /**
    139 * Implemented by script event listeners. Used to retrieve the script object
    140 * corresponding to the event target and the handler itself.
    141 *
    142 * Note, mTarget is a raw pointer and the owner of the JSEventHandler object
    143 * is expected to call Disconnect()!
    144 */
    145 
    146 #define NS_JSEVENTHANDLER_IID \
    147  {0x4f486881, 0x1956, 0x4079, {0x8c, 0xa0, 0xf3, 0xbd, 0x60, 0x5c, 0xc2, 0x79}}
    148 
    149 class JSEventHandler : public nsIDOMEventListener {
    150 public:
    151  NS_INLINE_DECL_STATIC_IID(NS_JSEVENTHANDLER_IID)
    152 
    153  JSEventHandler(dom::EventTarget* aTarget, nsAtom* aType,
    154                 const TypedEventHandler& aTypedHandler);
    155 
    156  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
    157 
    158  // nsIDOMEventListener interface
    159  NS_DECL_NSIDOMEVENTLISTENER
    160 
    161  void Disconnect() { mTarget = nullptr; }
    162 
    163  const TypedEventHandler& GetTypedEventHandler() const {
    164    return mTypedHandler;
    165  }
    166 
    167  void ForgetHandler() { mTypedHandler.ForgetHandler(); }
    168 
    169  nsAtom* EventName() const { return mEventName; }
    170 
    171  // Set a handler for this event listener.  The handler must already
    172  // be bound to the right target.
    173  void SetHandler(const TypedEventHandler& aTypedHandler) {
    174    mTypedHandler.SetHandler(aTypedHandler);
    175  }
    176  void SetHandler(dom::EventHandlerNonNull* aHandler) {
    177    mTypedHandler.SetHandler(aHandler);
    178  }
    179  void SetHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler) {
    180    mTypedHandler.SetHandler(aHandler);
    181  }
    182  void SetHandler(dom::OnErrorEventHandlerNonNull* aHandler) {
    183    mTypedHandler.SetHandler(aHandler);
    184  }
    185 
    186  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
    187    return 0;
    188 
    189    // Measurement of the following members may be added later if DMD finds it
    190    // is worthwhile:
    191    // - mTarget
    192    //
    193    // The following members are not measured:
    194    // - mTypedHandler: may be shared with others
    195    // - mEventName: shared with others
    196  }
    197 
    198  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) {
    199    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
    200  }
    201 
    202  NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS(JSEventHandler)
    203 
    204  bool IsBlackForCC();
    205 
    206 protected:
    207  virtual ~JSEventHandler();
    208 
    209  dom::EventTarget* mTarget;
    210  RefPtr<nsAtom> mEventName;
    211  TypedEventHandler mTypedHandler;
    212 };
    213 
    214 }  // namespace mozilla
    215 
    216 /**
    217 * Factory function.  aHandler must already be bound to aTarget.
    218 * aContext is allowed to be null if aHandler is already set up.
    219 */
    220 nsresult NS_NewJSEventHandler(mozilla::dom::EventTarget* aTarget, nsAtom* aType,
    221                              const mozilla::TypedEventHandler& aTypedHandler,
    222                              mozilla::JSEventHandler** aReturn);
    223 
    224 #endif  // mozilla_JSEventHandler_h_