/// <summary>
/// Populate the fields of this object by copying them from equivalent fields on
/// another object. The fields to be copied must share names and types in order to
/// be successfully transferred.
/// The CopyAttribute will be used to determine the correct behaviour when copying fields
/// accross - first on the field itself and then, if not set, on the type of the field.
/// If neither of these is specified the default is to do a 'shallow' or reference-copy on all objects
/// except for collection type, where the default is to not copy any fields *unless* they are
/// specifically annotated.
/// </summary>
/// <param name="source">The object to copy fields from.</param>
/// <param name="objectMap">A map of original objects to their copies. Used when duplicating multiple
/// objects at once to create links between them of the same relative relationships.</param>
public static void CopyFieldsFrom(this object target, object source, ref Dictionary <object, object> objectMap)
{
Type targetType = target.GetType();
Type sourceType = source.GetType();
BindingFlags flags = BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy;
ICollection <FieldInfo> fields = targetType.GetAllFields(flags);
foreach (FieldInfo targetField in fields)
{
FieldInfo sourceField = sourceType.GetBaseField(targetField.Name, flags);
if (sourceField != null && targetField.FieldType.IsAssignableFrom(sourceField.FieldType))
{
// Have found a matching property - check for copy behaviour attributes:
// Currently this is done on the source field. Might it also be safer to check the target
// field as well, for at least certain values?
CopyAttribute copyAtt = sourceField.GetAttribute <CopyAttribute>();
// If copy attribute is not set on the field, we will try it on the type:
if (copyAtt == null)
{
copyAtt = sourceField.FieldType.GetCustomAttribute <CopyAttribute>();
}
CopyBehaviour behaviour = CopyBehaviour.COPY;
CopyBehaviour itemsBehaviour = CopyBehaviour.COPY;
if (sourceType.IsCollection())
{
behaviour = CopyBehaviour.DO_NOT_COPY; //By default, do not copy fields from collection types
}
if (copyAtt != null)
{
behaviour = copyAtt.Behaviour;
if (copyAtt is CollectionCopyAttribute)
{
itemsBehaviour = ((CollectionCopyAttribute)copyAtt).ItemsBehaviour;
}
}
if (behaviour != CopyBehaviour.DO_NOT_COPY)
{
object value = sourceField.GetValue(source);
value = ValueToAssign(value, ref behaviour, itemsBehaviour, ref objectMap);
if (behaviour != CopyBehaviour.DO_NOT_COPY)
{
targetField.SetValue(target, value);
}
}
}
}
}
/// <summary>
/// Produce a duplicated copy of this object.
/// Family references will be copied, save for those which
/// are intended to be unique to this object, which will themselves
/// be duplicated.
/// </summary>
/// <param name="objectMap">The map of original objects to duplicated objects.</param>
/// <returns>A duplicated copy of this object</returns>
public static T Duplicate <T>(this T obj, ref Dictionary <object, object> objectMap, CopyBehaviour itemsBehaviour = CopyBehaviour.COPY)
where T : IDuplicatable
{
T clone;
if (obj.GetType().HasParameterlessConstructor())
{
clone = (T)Activator.CreateInstance(obj.GetType(), true); //Create a blank instance of the relevant type
}
else
{
#if !JS
// As a (potentially dangerous) fallback:
clone = (T)FormatterServices.GetUninitializedObject(obj.GetType());
//Special cludge for Uniques to avoid having all-0 GUIDs:
if (clone is IUniqueWithModifiableGUID)
{
((IUniqueWithModifiableGUID)clone).SetGUID(Guid.NewGuid());
}
#else
throw new NotSupportedException("Class to be duplicated does not provide a parameterless constructor!");
#endif
}
if (objectMap == null)
{
objectMap = new Dictionary <object, object>();
}
objectMap[obj] = clone; //Store the original-clone relationship in the map
clone.CopyFieldsFrom(obj, ref objectMap);
if (obj.GetType().IsCollection() && itemsBehaviour != CopyBehaviour.DO_NOT_COPY)
{
ICollection source = (ICollection)obj;
ICollection target = (ICollection)clone;
foreach (object item in source)
{
CopyBehaviour behaviour = itemsBehaviour;
CopyBehaviour subItemsBehaviour = itemsBehaviour;
if (item != null && item is IDuplicatable)
{
CopyAttribute cAtt = item.GetType().GetCustomAttribute <CopyAttribute>();
if (cAtt != null)
{
behaviour = cAtt.Behaviour;
if (cAtt is CollectionCopyAttribute)
{
subItemsBehaviour = ((CollectionCopyAttribute)cAtt).ItemsBehaviour;
}
}
}
object value = ValueToAssign(item, ref behaviour, subItemsBehaviour, ref objectMap);
if (target is IList)
{
((IList)target).Add(value);
}
// TODO: Other types of collections?
}
}
return(clone);
}
