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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef EXTENSIONS_RENDERER_BINDINGS_EVENT_EMITTER_H_
#define EXTENSIONS_RENDERER_BINDINGS_EVENT_EMITTER_H_
#include <map>
#include "base/memory/raw_ptr.h"
#include "extensions/common/mojom/event_dispatcher.mojom-forward.h"
#include "extensions/renderer/bindings/js_runner.h"
#include "gin/wrappable.h"
#include "v8/include/v8.h"
namespace gin {
class Arguments;
}
namespace extensions {
class APIEventListeners;
class ExceptionHandler;
// A gin::Wrappable Event object. One is expected to be created per event, per
// context. Note: this object *does not* clear any events, so it must be
// destroyed with the context to avoid leaking.
class EventEmitter final : public gin::Wrappable<EventEmitter> {
public:
EventEmitter(bool supports_filters,
std::unique_ptr<APIEventListeners> listeners,
ExceptionHandler* exception_handler);
EventEmitter(const EventEmitter&) = delete;
EventEmitter& operator=(const EventEmitter&) = delete;
~EventEmitter() override;
static gin::WrapperInfo kWrapperInfo;
// gin::Wrappable:
gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
v8::Isolate* isolate) final;
const char* GetTypeName() final;
// Fires the event to any listeners.
// Warning: This can run arbitrary JS code, so the `context` may be
// invalidated after this!
void Fire(v8::Local<v8::Context> context,
v8::LocalVector<v8::Value>* args,
mojom::EventFilteringInfoPtr filter,
JSRunner::ResultCallback callback);
// Fires the event to any listeners synchronously, and returns the result.
// This should only be used if the caller is certain that JS is already
// running (i.e., is not blocked).
// Warning: This can run arbitrary JS code, so the `context` may be
// invalidated after this!
v8::Local<v8::Value> FireSync(v8::Local<v8::Context> context,
v8::LocalVector<v8::Value>* args,
mojom::EventFilteringInfoPtr filter);
// Removes all listeners and marks this object as invalid so that no more
// are added.
void Invalidate(v8::Local<v8::Context> context);
// TODO(devlin): Consider making this a test-only method and exposing
// HasListeners() instead.
size_t GetNumListeners() const;
// Saves a given filter in an internal filter_id based mapping. This is
// needed in order to allow asynchronous usage of filters.
// Returns this filter's filter_id, which may be kInvalidFilterId if
// `filter` is empty.
int PushFilter(mojom::EventFilteringInfoPtr filter);
// Fetches a given filter by it's filter_id and removes it from the internal
// storage. In case of a kInvalidFilterId, an empty
// mojom::EventFilteringInfoPtr is returned.
mojom::EventFilteringInfoPtr PopFilter(int filter_id);
private:
// Bound methods for the Event JS object.
void AddListener(gin::Arguments* arguments);
void RemoveListener(gin::Arguments* arguments);
bool HasListener(v8::Local<v8::Function> function);
bool HasListeners();
void Dispatch(gin::Arguments* arguments);
// Dispatches an event synchronously to listeners, returning the result.
v8::Local<v8::Value> DispatchSync(v8::Local<v8::Context> context,
v8::LocalVector<v8::Value>* args,
mojom::EventFilteringInfoPtr filter);
// Dispatches an event asynchronously to listeners.
void DispatchAsync(v8::Local<v8::Context> context,
v8::LocalVector<v8::Value>* args,
mojom::EventFilteringInfoPtr filter,
JSRunner::ResultCallback callback);
static void DispatchAsyncHelper(
const v8::FunctionCallbackInfo<v8::Value>& info);
// Whether or not this object is still valid; false upon context release.
// When invalid, no listeners can be added or removed.
bool valid_ = true;
// Whether the event supports filters.
bool supports_filters_ = false;
std::unique_ptr<APIEventListeners> listeners_;
// The associated exception handler; guaranteed to outlive this object.
const raw_ptr<ExceptionHandler, DanglingUntriaged> exception_handler_ =
nullptr;
// The next id to use in the pending_filters_ map.
int next_filter_id_ = 0;
// A constant to indicate an invalid id.
static constexpr int kInvalidFilterId = -1;
// The map of EventFilteringInfos for events that are pending dispatch (since
// JS is suspended).
std::map<int, mojom::EventFilteringInfoPtr> pending_filters_;
};
} // namespace extensions
#endif // EXTENSIONS_RENDERER_BINDINGS_EVENT_EMITTER_H_
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