third_party/WebKit/Source/bindings/core/v8/V8AbstractEventListener.h

/*
 * Copyright (C) 2006, 2007, 2008, 2009 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef V8AbstractEventListener_h
#define V8AbstractEventListener_h

#include "bindings/core/v8/DOMWrapperWorld.h"
#include "bindings/core/v8/ScriptWrappable.h"
#include "bindings/core/v8/TraceWrapperV8Reference.h"
#include "core/CoreExport.h"
#include "core/events/EventListener.h"
#include "platform/heap/SelfKeepAlive.h"
#include "v8/include/v8.h"

namespace blink {

class Event;
class WorkerGlobalScope;

// There are two kinds of event listeners: HTML or non-HMTL. onload,
// onfocus, etc (attributes) are always HTML event handler type; Event
// listeners added by Window.addEventListener or
// EventTargetNode::addEventListener are non-HTML type.
//
// Why does this matter?
// WebKit does not allow duplicated HTML event handlers of the same type,
// but ALLOWs duplicated non-HTML event handlers.
class CORE_EXPORT V8AbstractEventListener : public EventListener,
                                            public TraceWrapperBase {
 public:
  ~V8AbstractEventListener() override;

  static const V8AbstractEventListener* cast(const EventListener* listener) {
    return listener->type() == JSEventListenerType
               ? static_cast<const V8AbstractEventListener*>(listener)
               : 0;
  }

  static V8AbstractEventListener* cast(EventListener* listener) {
    return const_cast<V8AbstractEventListener*>(
        cast(const_cast<const EventListener*>(listener)));
  }

  // Implementation of EventListener interface.

  bool operator==(const EventListener& other) const override {
    return this == &other;
  }

  void handleEvent(ExecutionContext*, Event*) final;
  virtual void handleEvent(ScriptState*, Event*);

  v8::Local<v8::Value> getListenerOrNull(v8::Isolate* isolate,
                                         ExecutionContext* executionContext) {
    v8::Local<v8::Object> listener = getListenerObject(executionContext);
    return listener.IsEmpty() ? v8::Null(isolate).As<v8::Value>()
                              : listener.As<v8::Value>();
  }

  // Returns the listener object, either a function or an object, or the empty
  // handle if the user script is not compilable.  No exception will be thrown
  // even if the user script is not compilable.
  v8::Local<v8::Object> getListenerObject(ExecutionContext* executionContext) {
    return getListenerObjectInternal(executionContext);
  }

  v8::Local<v8::Object> getExistingListenerObject() {
    return m_listener.newLocal(m_isolate);
  }

  // Provides access to the underlying handle for GC. Returned
  // value is a weak handle and so not guaranteed to stay alive.
  v8::Persistent<v8::Object>& existingListenerObjectPersistentHandle() {
    return m_listener.get();
  }

  bool hasExistingListenerObject() { return !m_listener.isEmpty(); }

  void clearListenerObject();

  bool belongsToTheCurrentWorld(ExecutionContext*) const final;
  v8::Isolate* isolate() const { return m_isolate; }
  DOMWrapperWorld& world() const { return *m_world; }

  DECLARE_VIRTUAL_TRACE();
  DECLARE_VIRTUAL_TRACE_WRAPPERS();

 protected:
  V8AbstractEventListener(bool isAttribute, DOMWrapperWorld&, v8::Isolate*);

  virtual v8::Local<v8::Object> getListenerObjectInternal(
      ExecutionContext* executionContext) {
    return getExistingListenerObject();
  }

  void setListenerObject(v8::Local<v8::Object>);

  void invokeEventHandler(ScriptState*, Event*, v8::Local<v8::Value>);

  // Get the receiver object to use for event listener call.
  v8::Local<v8::Object> getReceiverObject(ScriptState*, Event*);

 private:
  // Implementation of EventListener function.
  bool virtualisAttribute() const override { return m_isAttribute; }

  // This could return an empty handle and callers need to check return value.
  // We don't use v8::MaybeLocal because it can fail without exception.
  virtual v8::Local<v8::Value>
  callListenerFunction(ScriptState*, v8::Local<v8::Value> jsevent, Event*) = 0;

  virtual bool shouldPreventDefault(v8::Local<v8::Value> returnValue);

  static void wrapperCleared(
      const v8::WeakCallbackInfo<V8AbstractEventListener>&);

  TraceWrapperV8Reference<v8::Object> m_listener;

  // Indicates if this is an HTML type listener.
  bool m_isAttribute;

  RefPtr<DOMWrapperWorld> m_world;
  v8::Isolate* m_isolate;

  // nullptr unless this listener belongs to a worker.
  Member<WorkerGlobalScope> m_workerGlobalScope;

  SelfKeepAlive<V8AbstractEventListener> m_keepAlive;
};

}  // namespace blink

#endif  // V8AbstractEventListener_h