components/js_injection/renderer/js_binding.h

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_JS_INJECTION_RENDERER_JS_BINDING_H_
#define COMPONENTS_JS_INJECTION_RENDERER_JS_BINDING_H_

#include <algorithm>
#include <string>
#include <vector>

#include "base/auto_reset.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "components/js_injection/common/interfaces.mojom.h"
#include "gin/arguments.h"
#include "gin/public/wrappable_pointer_tags.h"
#include "gin/wrappable.h"
#include "mojo/public/cpp/bindings/associated_receiver.h"
#include "third_party/blink/public/common/messaging/string_message_codec.h"
#include "v8/include/v8.h"
#include "v8/include/cppgc/persistent.h"

namespace v8 {
template <typename T>
class Global;
class Function;
}  // namespace v8

namespace content {
class RenderFrame;
}  // namespace content

namespace js_injection {
class JsCommunication;

// A gin::DeprecatedWrappable class used for providing JavaScript API.
// JsCommunication creates an instance of JsBinding for each unique name exposed
// to the page. JsBinding is owned by v8.
class JsBinding final : public gin::Wrappable<JsBinding>,
                        public mojom::BrowserToJsMessaging {
 public:
  static constexpr gin::WrapperInfo kWrapperInfo = {
      {gin::kEmbedderNativeGin}, gin::kJsBinding};

  JsBinding(const JsBinding&) = delete;
  JsBinding& operator=(const JsBinding&) = delete;

  // Make public for cppgc::MakeGarbageCollected.
  JsBinding(content::RenderFrame* render_frame,
                     const std::u16string& js_object_name,
                     base::WeakPtr<JsCommunication> js_communication);
  ~JsBinding() override;

  static cppgc::WeakPersistent<JsBinding> Install(
      content::RenderFrame* render_frame,
      const std::u16string& js_object_name,
      base::WeakPtr<JsCommunication> js_communication,
      v8::Isolate* isolate,
      v8::Local<v8::Context> context);

  // mojom::BrowserToJsMessaging implementation.
  void OnPostMessage(blink::WebMessagePayload message) override;

  void ReleaseV8GlobalObjects();

  void Bind(
      mojo::PendingAssociatedReceiver<mojom::BrowserToJsMessaging> receiver);

 private:
  // gin::WrappableBase implementation.
  gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
      v8::Isolate* isolate) override;
  const gin::WrapperInfo* wrapper_info() const override;

  auto find_listener(v8::Local<v8::Function> listener) {
    // Can't just use `find(listeners_, listener)` because `v8::Global<T>` and
    // `v8::Local<T>` do not have a common reference type and thus do not
    // satisfy `std::equality_comparable_with<>`. We could project using
    // `v8::Global<T>::Get()`, but that's less efficient.
    return std::ranges::find_if(listeners_,
                                [listener](const auto& global_listener) {
                                  return global_listener == listener;
                                });
  }

  // For jsObject.postMessage(message[, ports]) JavaScript API.
  void PostMessage(gin::Arguments* args);
  // For jsObject.addEventListener("message", listener) JavaScript API.
  void AddEventListener(gin::Arguments* args);
  // For jsObject.removeEventListener("message", listener) JavaScript API.
  void RemoveEventListener(gin::Arguments* args);
  // For get jsObject.onmessage.
  v8::Local<v8::Function> GetOnMessage(v8::Isolate* isolate);
  // For set jsObject.onmessage.
  void SetOnMessage(v8::Isolate* isolate, v8::Local<v8::Value> value);

  raw_ptr<content::RenderFrame> render_frame_;
  std::u16string js_object_name_;
  v8::Global<v8::Function> on_message_;
  std::vector<v8::Global<v8::Function>> listeners_;

  base::WeakPtr<JsCommunication> js_communication_;

  mojo::AssociatedReceiver<mojom::BrowserToJsMessaging> receiver_{this};
};

}  // namespace js_injection

#endif  // COMPONENTS_JS_INJECTION_RENDERER_JS_BINDING_H_