gecko-dev/dom/xul/XULBroadcastManager.h

/* -*- 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/. */

#ifndef mozilla_dom_XULBroadcastManager_h
#define mozilla_dom_XULBroadcastManager_h

#include "mozilla/dom/Element.h"
#include "nsAtom.h"

class nsXULElement;

namespace mozilla {
namespace dom {

class XULBroadcastManager final {
 public:
  explicit XULBroadcastManager(Document* aDocument);

  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(XULBroadcastManager)

  /**
   * Checks whether an element uses any of the special broadcaster attributes
   * or is an observes element. This mimics the logic in FindBroadcaster, but
   * is intended to be a lighter weight check and doesn't actually guarantee
   * that the element will need a listener.
   */
  static bool MayNeedListener(const Element& aElement);

  nsresult AddListener(Element* aElement);
  nsresult RemoveListener(Element* aElement);
  void AttributeChanged(Element* aElement, int32_t aNameSpaceID,
                        nsAtom* aAttribute);
  void MaybeBroadcast();
  void DropDocumentReference();  // notification that doc is going away
 protected:
  enum HookupAction { eHookupAdd = 0, eHookupRemove };

  nsresult UpdateListenerHookup(Element* aElement, HookupAction aAction);

  void RemoveListenerFor(Element& aBroadcaster, Element& aListener,
                         const nsAString& aAttr);
  void AddListenerFor(Element& aBroadcaster, Element& aListener,
                      const nsAString& aAttr, ErrorResult& aRv);

  nsresult ExecuteOnBroadcastHandlerFor(Element* aBroadcaster,
                                        Element* aListener, nsAtom* aAttr);
  // The out params of FindBroadcaster only have values that make sense when
  // the method returns NS_FINDBROADCASTER_FOUND.  In all other cases, the
  // values of the out params should not be relied on (though *aListener and
  // *aBroadcaster do need to be released if non-null, of course).
  nsresult FindBroadcaster(Element* aElement, Element** aListener,
                           nsString& aBroadcasterID, nsString& aAttribute,
                           Element** aBroadcaster);

  void SynchronizeBroadcastListener(Element* aBroadcaster, Element* aListener,
                                    const nsAString& aAttr);

  // This reference is nulled by the Document in it's destructor through
  // DropDocumentReference().
  Document* MOZ_NON_OWNING_REF mDocument;

  /**
   * A map from a broadcaster element to a list of listener elements.
   */
  PLDHashTable* mBroadcasterMap;

  class nsDelayedBroadcastUpdate {
   public:
    nsDelayedBroadcastUpdate(Element* aBroadcaster, Element* aListener,
                             const nsAString& aAttr)
        : mBroadcaster(aBroadcaster),
          mListener(aListener),
          mAttr(aAttr),
          mSetAttr(false),
          mNeedsAttrChange(false) {}

    nsDelayedBroadcastUpdate(Element* aBroadcaster, Element* aListener,
                             nsAtom* aAttrName, const nsAString& aAttr,
                             bool aSetAttr, bool aNeedsAttrChange)
        : mBroadcaster(aBroadcaster),
          mListener(aListener),
          mAttr(aAttr),
          mAttrName(aAttrName),
          mSetAttr(aSetAttr),
          mNeedsAttrChange(aNeedsAttrChange) {}

    nsDelayedBroadcastUpdate(const nsDelayedBroadcastUpdate& aOther)
        : mBroadcaster(aOther.mBroadcaster),
          mListener(aOther.mListener),
          mAttr(aOther.mAttr),
          mAttrName(aOther.mAttrName),
          mSetAttr(aOther.mSetAttr),
          mNeedsAttrChange(aOther.mNeedsAttrChange) {}

    nsCOMPtr<Element> mBroadcaster;
    nsCOMPtr<Element> mListener;
    // Note if mAttrName isn't used, this is the name of the attr, otherwise
    // this is the value of the attribute.
    nsString mAttr;
    RefPtr<nsAtom> mAttrName;
    bool mSetAttr;
    bool mNeedsAttrChange;

    class Comparator {
     public:
      static bool Equals(const nsDelayedBroadcastUpdate& a,
                         const nsDelayedBroadcastUpdate& b) {
        return a.mBroadcaster == b.mBroadcaster && a.mListener == b.mListener &&
               a.mAttrName == b.mAttrName;
      }
    };
  };
  nsTArray<nsDelayedBroadcastUpdate> mDelayedBroadcasters;
  nsTArray<nsDelayedBroadcastUpdate> mDelayedAttrChangeBroadcasts;
  bool mHandlingDelayedAttrChange;
  bool mHandlingDelayedBroadcasters;

 private:
  ~XULBroadcastManager();
};

}  // namespace dom
}  // namespace mozilla

#endif  // mozilla_dom_XULBroadcastManager_h