blob: a1f0d2eacf5b405887ce9e2c4c6c46f1dee03c0c [file] [log] [blame]
// Copyright (c) 2012 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 CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_USER_DATA_H_
#define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_USER_DATA_H_
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/supports_user_data.h"
#include "content/public/browser/web_contents.h"
#define WEB_CONTENTS_USER_DATA_KEY_DECL() static constexpr int kUserDataKey = 0;
#define WEB_CONTENTS_USER_DATA_KEY_IMPL(Type) const int Type::kUserDataKey;
namespace content {
// A base class for classes attached to, and scoped to, the lifetime of a
// WebContents. For example:
//
// --- in foo_tab_helper.h ---
// class FooTabHelper : public content::WebContentsUserData<FooTabHelper> {
// public:
// ~FooTabHelper() override;
// // ... more public stuff here ...
// private:
// explicit FooTabHelper(content::WebContents* contents);
// friend class content::WebContentsUserData<FooTabHelper>;
// WEB_CONTENTS_USER_DATA_KEY_DECL();
// // ... more private stuff here ...
// };
//
// --- in foo_tab_helper.cc ---
// WEB_CONTENTS_USER_DATA_KEY_IMPL(FooTabHelper)
template <typename T>
class WebContentsUserData : public base::SupportsUserData::Data {
public:
// Creates an object of type T, and attaches it to the specified WebContents.
// If an instance is already attached, does nothing.
static void CreateForWebContents(WebContents* contents) {
DCHECK(contents);
if (!FromWebContents(contents))
contents->SetUserData(UserDataKey(), base::WrapUnique(new T(contents)));
}
// Retrieves the instance of type T that was attached to the specified
// WebContents (via CreateForWebContents above) and returns it. If no instance
// of the type was attached, returns nullptr.
static T* FromWebContents(WebContents* contents) {
DCHECK(contents);
return static_cast<T*>(contents->GetUserData(UserDataKey()));
}
static const T* FromWebContents(const WebContents* contents) {
DCHECK(contents);
return static_cast<const T*>(contents->GetUserData(UserDataKey()));
}
static const void* UserDataKey() { return &T::kUserDataKey; }
};
} // namespace content
#endif // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_USER_DATA_H_