internal bool AddElement(GraphElement element)
{
Ensure.Argument.NotNull(element, nameof(element));
var owner = element.Owner;
if (owner != null)
{
if (owner == this)
{
return(false);
}
throw new InvalidOperationException(
"Attempt to add element which belongs to another graph to current graph.");
}
bool added = _elements.Add(element);
Debug.Assert(added);
element._OnAddedToGraph(this);
OnElementAdded(element);
ElementAdded?.Invoke(this, element);
return(true);
}
internal bool RemoveElement(GraphElement element)
{
Ensure.Argument.NotNull(element, nameof(element));
if (element.Owner != this)
{
return(false);
}
ElementRemoving?.Invoke(this, element);
OnElementRemoving(element);
element._OnRemovingFromGraph(this);
bool removed = _elements.Remove(element);
Debug.Assert(removed);
return(true);
}
/// <summary>
/// Event method for derived classes automatically invoked before any element is removing from current graph.
/// Note that the method is invoked after the public event <see cref="ElementRemoving" />.
/// </summary>
/// <param name="element">The element about to remove.</param>
protected virtual void OnElementRemoving(GraphElement element)
{
}
/// <summary>
/// Event method for derived classes automatically invoked after any element is added to current graph. Note
/// that the method is invoked before the public event <see cref="ElementAdded" />.
/// </summary>
/// <param name="element">The newly added element.</param>
protected virtual void OnElementAdded(GraphElement element)
{
}
/// <summary>
/// Get a value indicates whether the specified <see cref="GraphElement" /> is part of current graph.
/// </summary>
/// <param name="element">The element instance to test.</param>
/// <returns>
/// <see langword="true" /> if the specified <see cref="GraphElement" /> is part of current graph; otherwise,
/// <see langword="false" />.
/// </returns>
public bool Contains(GraphElement element)
{
return(_elements.Contains(element));
}