third_party/WebKit/Source/platform/EventDispatchForbiddenScope.h

// 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.

#ifndef EventDispatchForbiddenScope_h
#define EventDispatchForbiddenScope_h

#include "platform/PlatformExport.h"
#include "wtf/Allocator.h"
#include "wtf/Assertions.h"
#include "wtf/AutoReset.h"

namespace blink {

#if DCHECK_IS_ON()

class EventDispatchForbiddenScope {
  STACK_ALLOCATED();
  WTF_MAKE_NONCOPYABLE(EventDispatchForbiddenScope);

 public:
  EventDispatchForbiddenScope() {
    ASSERT(isMainThread());
    ++s_count;
  }

  ~EventDispatchForbiddenScope() {
    ASSERT(isMainThread());
    ASSERT(s_count);
    --s_count;
  }

  static bool isEventDispatchForbidden() {
    if (!isMainThread())
      return false;
    return s_count;
  }

  class AllowUserAgentEvents {
    STACK_ALLOCATED();

   public:
    AllowUserAgentEvents() : m_change(&s_count, 0) { ASSERT(isMainThread()); }

    ~AllowUserAgentEvents() { ASSERT(!s_count); }

    AutoReset<unsigned> m_change;
  };

 private:
  PLATFORM_EXPORT static unsigned s_count;
};

#else

class EventDispatchForbiddenScope {
  STACK_ALLOCATED();
  WTF_MAKE_NONCOPYABLE(EventDispatchForbiddenScope);

 public:
  EventDispatchForbiddenScope() {}

  class AllowUserAgentEvents {
   public:
    AllowUserAgentEvents() {}
  };
};

#endif  // DCHECK_IS_ON()

}  // namespace blink

#endif  // EventDispatchForbiddenScope_h