/// <summary>
/// Removes the stored item.
/// </summary>
/// <returns>True if the item was removed, false otherwise</returns>
public bool Remove(T item, UnorderedListMetadata metadata)
{
// the metadata says the item is not in the collection
if (metadata.Index == -1)
{
return(false);
}
int index = metadata.Index;
metadata.Index = -1;
metadata.StoredIn = null;
// nothing to remove if we are empty
if (Length == 0)
{
return(false);
}
StoredItem replacer = Pop();
// If the item to remove was the item at the end of the list or there are no items left
// then the popped item was equal to the item itself, so just return
if (index == Length || Length == 0)
{
return(true);
}
// Replace the removed item with the popped item.
replacer.Metadata.Index = index;
replacer.Metadata.StoredIn = this;
Items[index] = replacer;
return(true);
}
/// <summary>
/// Checks to see if the given item is contained in the UnorderedList. This is O(1).
/// </summary>
/// <param name="item">The item to check</param>
/// <param name="metadata">The item's metadata</param>
/// <returns>True if the item is contained, false otherwise</returns>
public bool Contains(T item, UnorderedListMetadata metadata)
{
if (metadata.Index < 0)
{
return(false);
}
if (metadata.Index >= Length)
{
return(false);
}
return(EqualityComparer <T> .Default.Equals(Items[metadata.Index].Item, item));
}
/// <summary>
/// Adds an item to the list. The location of the item in the list is unspecified.
/// </summary>
public void Add(T item, UnorderedListMetadata metadata)
{
// Make sure the item is not in another list
if (metadata.Index != -1)
{
throw new Exception(String.Format("Item {0} is already stored in another UnorderedList, or has been added twice to the same one", item));
}
// Grow the array if necessary
if (Length == Items.Length)
{
Array.Resize(ref Items, Items.Length * 2);
}
// Add the item
metadata.Index = Length;
metadata.StoredIn = this;
Items[Length++] = new StoredItem()
{
Item = item,
Metadata = metadata
};
}