third_party/WebKit/Source/core/frame/PlatformEventDispatcher.cpp

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "core/frame/PlatformEventDispatcher.h"

#include "core/frame/PlatformEventController.h"
#include "wtf/AutoReset.h"

namespace blink {

PlatformEventDispatcher::PlatformEventDispatcher()
    : m_isDispatching(false), m_isListening(false) {}

void PlatformEventDispatcher::addController(
    PlatformEventController* controller) {
  ASSERT(controller);
  // TODO: If we can avoid to register a same controller twice, we can change
  // this 'if' to ASSERT.
  if (m_controllers.contains(controller))
    return;

  m_controllers.add(controller);

  if (!m_isListening) {
    startListening();
    m_isListening = true;
  }
}

void PlatformEventDispatcher::removeController(
    PlatformEventController* controller) {
  ASSERT(m_controllers.contains(controller));

  m_controllers.remove(controller);
  if (!m_isDispatching && m_controllers.isEmpty()) {
    stopListening();
    m_isListening = false;
  }
}

void PlatformEventDispatcher::notifyControllers() {
  if (m_controllers.isEmpty())
    return;

  {
    AutoReset<bool> changeIsDispatching(&m_isDispatching, true);
    // HashSet m_controllers can be updated during an iteration, and it stops
    // the iteration.  Thus we store it into a Vector to access all elements.
    HeapVector<Member<PlatformEventController>> snapshotVector;
    copyToVector(m_controllers, snapshotVector);
    for (PlatformEventController* controller : snapshotVector) {
      if (m_controllers.contains(controller))
        controller->didUpdateData();
    }
  }

  if (m_controllers.isEmpty()) {
    stopListening();
    m_isListening = false;
  }
}

DEFINE_TRACE(PlatformEventDispatcher) {
  visitor->trace(m_controllers);
}

}  // namespace blink