/// <summary>
/// removes the next element(s) if any.
/// </summary>
internal void RemoveNext()
{
if (_next != null)
{
FrameCacheItem next = _next;
_next = null;
next._previous = null;
next._value = null; //releasing the element just in case to avoid any risk of memory leak.
next._uri = null;
next.RemoveNext(); //we remove all the next elements recursively.
}
}
internal FrameCacheItem GoForward()
{
if (CanGoForward)
{
_currentItem = _currentItem._next;
return(_currentItem);
}
else
{
throw new InvalidOperationException("There are no entries in the forward navigation history.");
}
}
//note: I kept it because the algorithm might be useful when we will have figured out what CacheSize means.
///// <summary>
///// Adds the item to the cache, and handles the cases where:
///// - it is the first item,
///// - we add it to the end
///// - we add it somewhere else.
///// </summary>
///// <param name="next"></param>
//internal void Add(object next, Uri uri)
//{
// FrameCacheItem nextFrameCacheItem = new FrameCacheItem(next, uri);
// if (_currentItem != null)
// {
// int amountRemoved = _currentItem.RemoveNext();
// _currentItem._next = nextFrameCacheItem;
// nextFrameCacheItem._previous = _currentItem;
// _currentAmount -= amountRemoved - 1; //-1 because we added back the nextFrameCacheItem.
// if (_currentAmount > _cacheSize)
// {
// if (_cacheSize > 1) //would be stupid but not impossible
// {
// //we remove the first item of the list, and give its position as the first item to its next.
// FrameCacheItem oldFirst = firstItem;
// firstItem = firstItem._next;
// oldFirst._next = null;
// oldFirst._value = null;
// firstItem._previous = null;
// }
// else
// {
// firstItem = nextFrameCacheItem;
// }
// _currentAmount = _cacheSize;
// }
// }
// else //this is the first item in the cache:
// {
// firstItem = nextFrameCacheItem;
// ++_currentAmount;
// }
// _currentItem = nextFrameCacheItem;
//}
#endregion
internal FrameCacheItem GoBack()
{
if (CanGoBack)
{
_currentItem = _currentItem._previous;
return(_currentItem);
}
else
{
throw new InvalidOperationException("There are no entries in the back navigation history.");
}
}
/// <summary>
/// Adds the item to the cache, and handles the cases where:
/// - it is the first item,
/// - we add it to the end
/// - we add it somewhere else.
/// </summary>
/// <param name="next"></param>
/// <param name="uri"></param>
internal void Add(object next, Uri uri)
{
FrameCacheItem nextFrameCacheItem = new FrameCacheItem(next, uri);
if (_currentItem != null)
{
_currentItem.RemoveNext(); //we remove any item that was after the current item.
//we set the new item as the next of the current one:
_currentItem._next = nextFrameCacheItem;
nextFrameCacheItem._previous = _currentItem;
}
else //this is the first item in the cache:
{
firstItem = nextFrameCacheItem;
}
//we set the new item as the current one.
_currentItem = nextFrameCacheItem;
}
internal void Clear()
{
firstItem.RemoveNext();
firstItem = null;
}
