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// 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.
#include <stddef.h>
#include <memory>
#include <utility>
#include <vector>
#include "base/check_op.h"
#include "base/macros.h"
#include "base/observer_list.h"
#include "ui/base/models/list_model_observer.h"
namespace ui {
// A list model that manages a list of ItemType pointers. Items added to the
// model are owned by the model. An item can be taken out of the model by
// RemoveAt.
template <class ItemType>
class ListModel {
using ItemList = std::vector<std::unique_ptr<ItemType>>;
ListModel() {}
~ListModel() {}
// Adds |item| at the |index| into |items_|. Returns a raw pointer.
ItemType* AddAt(size_t index, std::unique_ptr<ItemType> item) {
DCHECK_LE(index, item_count());
ItemType* item_ptr = item.get();
items_.insert(items_.begin() + index, std::move(item));
NotifyItemsAdded(index, 1);
return item_ptr;
// Convenience function to append an item to the model.
ItemType* Add(std::unique_ptr<ItemType> item) {
return AddAt(item_count(), std::move(item));
// Removes the item at |index| from |items_| without deleting it.
// Returns a scoped pointer containing the removed item.
std::unique_ptr<ItemType> RemoveAt(size_t index) {
DCHECK_LT(index, item_count());
std::unique_ptr<ItemType> item = std::move(items_[index]);
items_.erase(items_.begin() + index);
NotifyItemsRemoved(index, 1);
return item;
// Removes all items from the model without deleting them.
// Returns a vector containing the removed items.
ItemList RemoveAll() {
ItemList result;
NotifyItemsRemoved(0, result.size());
return result;
// Removes the item at |index| from |items_| and deletes it.
void DeleteAt(size_t index) {
std::unique_ptr<ItemType> item = RemoveAt(index);
// |item| will be deleted on destruction.
// Removes and deletes all items from the model.
void DeleteAll() {
ItemList to_be_deleted;
NotifyItemsRemoved(0, to_be_deleted.size());
// Moves the item at |index| to |target_index|. |target_index| is in terms
// of the model *after* the item at |index| is removed.
void Move(size_t index, size_t target_index) {
DCHECK_LT(index, item_count());
DCHECK_LT(target_index, item_count());
if (index == target_index)
std::unique_ptr<ItemType> item = std::move(items_[index]);
items_.erase(items_.begin() + index);
items_.insert(items_.begin() + target_index, std::move(item));
NotifyItemMoved(index, target_index);
void AddObserver(ListModelObserver* observer) {
void RemoveObserver(ListModelObserver* observer) {
void NotifyItemsAdded(size_t start, size_t count) {
for (ListModelObserver& observer : observers_)
observer.ListItemsAdded(start, count);
void NotifyItemsRemoved(size_t start, size_t count) {
for (ListModelObserver& observer : observers_)
observer.ListItemsRemoved(start, count);
void NotifyItemMoved(size_t index, size_t target_index) {
for (ListModelObserver& observer : observers_)
observer.ListItemMoved(index, target_index);
void NotifyItemsChanged(size_t start, size_t count) {
for (ListModelObserver& observer : observers_)
observer.ListItemsChanged(start, count);
size_t item_count() const { return items_.size(); }
const ItemType* GetItemAt(size_t index) const {
DCHECK_LT(index, item_count());
return items_[index].get();
ItemType* GetItemAt(size_t index) {
return const_cast<ItemType*>(
const_cast<const ListModel<ItemType>*>(this)->GetItemAt(index));
// Iteration interface.
typename ItemList::iterator begin() { return items_.begin(); }
typename ItemList::const_iterator begin() const { return items_.begin(); }
typename ItemList::iterator end() { return items_.end(); }
typename ItemList::const_iterator end() const { return items_.end(); }
ItemList items_;
base::ObserverList<ListModelObserver>::Unchecked observers_;
} // namespace ui