ios/chrome/browser/web_state_list/web_state_list_observer.h

// Copyright 2017 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 IOS_CHROME_BROWSER_WEB_STATE_LIST_WEB_STATE_LIST_OBSERVER_H_
#define IOS_CHROME_BROWSER_WEB_STATE_LIST_WEB_STATE_LIST_OBSERVER_H_

#include "base/macros.h"

class WebStateList;

namespace web {
class WebState;
}

// Interface for listening to events occurring to WebStateLists.
class WebStateListObserver {
 public:
  // Constants used when notifying about changes to active WebState.
  enum ChangeReason {
    // Used to indicate that none of the reasons below are responsible for
    // the active WebState change.
    CHANGE_REASON_NONE = 0,

    // Used to indicate the active WebState changed because it was replaced.
    CHANGE_REASON_REPLACED = 1 << 0,

    // Used to indicate the active WebState changed due to a user action.
    CHANGE_REASON_USER_ACTION = 1 << 1,
  };

  WebStateListObserver();
  virtual ~WebStateListObserver();

  // Invoked after a new WebState has been added to the WebStateList at the
  // specified index. |activating| will be true if the WebState will become
  // the new active WebState after the insertion.
  virtual void WebStateInsertedAt(WebStateList* web_state_list,
                                  web::WebState* web_state,
                                  int index,
                                  bool activating);

  // Invoked after the WebState at the specified index is moved to another
  // index.
  virtual void WebStateMoved(WebStateList* web_state_list,
                             web::WebState* web_state,
                             int from_index,
                             int to_index);

  // Invoked after the WebState at the specified index is replaced by another
  // WebState.
  virtual void WebStateReplacedAt(WebStateList* web_state_list,
                                  web::WebState* old_web_state,
                                  web::WebState* new_web_state,
                                  int index);

  // Invoked before the specified WebState is detached from the WebStateList.
  // The WebState is still valid and still in the WebStateList.
  virtual void WillDetachWebStateAt(WebStateList* web_state_list,
                                    web::WebState* web_state,
                                    int index);

  // Invoked after the WebState at the specified index has been detached. The
  // WebState is still valid but is no longer in the WebStateList.
  virtual void WebStateDetachedAt(WebStateList* web_state_list,
                                  web::WebState* web_state,
                                  int index);

  // Invoked before the specified WebState is destroyed via the WebStateList.
  // The WebState is still valid but is no longer in the WebStateList. If the
  // WebState is closed due to user action, |user_action| will be true.
  virtual void WillCloseWebStateAt(WebStateList* web_state_list,
                                   web::WebState* web_state,
                                   int index,
                                   bool user_action);

  // Invoked after |new_web_state| was activated at the specified index. Both
  // WebState are either valid or null (if there was no selection or there is
  // no selection). If |reason| has CHANGE_REASON_USER_ACTION set then the
  // change is due to an user action. If |reason| has CHANGE_REASON_REPLACED
  // set then the change is caused because the WebState was replaced.
  virtual void WebStateActivatedAt(WebStateList* web_state_list,
                                   web::WebState* old_web_state,
                                   web::WebState* new_web_state,
                                   int active_index,
                                   int reason);

 private:
  DISALLOW_COPY_AND_ASSIGN(WebStateListObserver);
};

#endif  // IOS_CHROME_BROWSER_WEB_STATE_LIST_WEB_STATE_LIST_OBSERVER_H_