/// <summary>
/// Creates a deep copy of an object using the supplied dictionary of visited objects as
/// a source of objects already encountered in the copy traversal. The dictionary of visited
/// objects is used for holding objects that have already been copied, to avoid erroneous
/// duplication of parts of the object graph.
/// </summary>
/// <param name="instance">The object to be copied.</param>
/// <param name="visited">The graph of objects visited so far.</param>
/// <returns></returns>
private static object Clone(this object instance, VisitedGraph visited)
{
if (instance == null)
{
return(null);
}
Type instanceType = instance.GetType();
if (typeof(Type).IsAssignableFrom(instanceType))
{
return(instance);
}
if (instanceType.IsPointer || instanceType == typeof(Pointer) || instanceType.IsPrimitive || instanceType == typeof(string))
{
return(instance); // Pointers, primitive types and strings are considered immutable
}
if (instanceType.IsArray)
{
int length = ((Array)instance).Length;
Array copied = (Array)Activator.CreateInstance(instanceType, length);
visited.Add(instance, copied);
for (int i = 0; i < length; ++i)
{
copied.SetValue(((Array)instance).GetValue(i).Clone(visited), i);
}
return(copied);
}
return(Clone(instance, visited, DeduceInstance(instance)));
}
/// <summary>
/// Creates a deep copy of an object using the supplied dictionary of visited objects as
/// a source of objects already encountered in the copy traversal. The dictionary of visited
/// objects is used for holding objects that have already been copied, to avoid erroneous
/// duplication of parts of the object graph.
/// </summary>
/// <param name="instance">The object to be copied.</param>
/// <param name="visited">The graph of objects visited so far.</param>
/// <returns></returns>
private static object Clone(this object instance, VisitedGraph visited)
{
if (instance == null)
{
return(null);
}
Type instanceType = instance.GetType();
if (instanceType.IsValueType || instanceType == typeof(string))
{
return(instance); // Value types and strings are immutable
}
else if (instanceType.IsArray)
{
int length = ((Array)instance).Length;
Array copied = (Array)Activator.CreateInstance(instanceType, length);
visited.Add(instance, copied);
for (int i = 0; i < length; ++i)
{
copied.SetValue(((Array)instance).GetValue(i).Clone(visited), i);
}
return(copied);
}
else
{
return(Clone(instance, visited, DeduceInstance(instance)));
}
}
private static object Clone(this object instance, VisitedGraph visited, object copy)
{
if (visited.ContainsKey(instance))
{
return(visited[instance]);
}
else
{
visited.Add(instance, copy);
}
Type type = instance.GetType();
while (type != null)
{
foreach (FieldInfo field in type.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
{
object value = field.GetValue(instance);
if (visited.ContainsKey(value))
{
field.SetValue(copy, visited[value]);
}
else
{
field.SetValue(copy, value.Clone(visited));
}
}
type = type.BaseType;
}
return(copy);
}
private static object Clone(this object instance, VisitedGraph visited, object copy)
{
visited.Add(instance, copy);
foreach (
FieldInfo field in
instance.GetType().GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
{
object value = field.GetValue(instance);
if (visited.ContainsKey(value))
{
field.SetValue(copy, visited[value]);
}
else
{
field.SetValue(copy, value.Clone(visited));
}
}
return(copy);
}
