/// <summary>
/// The merge policy is expecting <c>asset2</c> to be the new base of <c>asset1</c>, and <c>base</c> the current base of <c>asset1</c>.
/// In case of conflicts:
/// <ul>
/// <li>If there is a type conflict, leave as-is</li>
/// <li>If there is a <see cref="Diff3ChangeType.Conflict"/>:
/// <ul>
/// <li>If it is on a member, and both <c>asset1</c> and <c>asset2</c> are not null and changes were done
/// in <c>asset2</c> but not in <c>asset1</c>, select <c>asset2</c> else select <c>asset1</c></li>
/// <li>If it is on a list item, we can't resolve it and leave the conflict as-is</li>
/// <li>If it is on a array item, we select <c>asset2</c></li>
/// </ul>
/// </li>
/// </ul>
/// </summary>
/// <param name="diff3Node">The diff3 node.</param>
/// <returns>.</returns>
public static Diff3ChangeType MergePolicyAsset2AsNewBaseOfAsset1(Diff3Node diff3Node)
{
var hasConflicts = diff3Node.ChangeType > Diff3ChangeType.Conflict;
if (hasConflicts)
{
return diff3Node.ChangeType;
}
switch (diff3Node.ChangeType)
{
case Diff3ChangeType.Conflict:
case Diff3ChangeType.MergeFromAsset2:
var dataNode = diff3Node.Asset2Node ?? diff3Node.Asset1Node ?? diff3Node.BaseNode;
if (dataNode is DataVisitMember)
{
if (diff3Node.Asset1Node != null && diff3Node.Asset2Node != null && diff3Node.ChangeType == Diff3ChangeType.MergeFromAsset2)
{
return Diff3ChangeType.MergeFromAsset2;
}
return Diff3ChangeType.MergeFromAsset1;
}
if (dataNode is DataVisitListItem)
{
// If we have a conflict in a list, we can't really resolve it here, so we are breaking out of the loop
if (diff3Node.ChangeType == Diff3ChangeType.Conflict)
{
return Diff3ChangeType.Conflict;
}
return Diff3ChangeType.MergeFromAsset2;
}
if (dataNode is DataVisitDictionaryItem)
{
return Diff3ChangeType.MergeFromAsset2;
}
if (dataNode is DataVisitArrayItem)
{
if (diff3Node.Asset1Node != null && ((DataVisitArrayItem)diff3Node.Asset1Node).Index == ((DataVisitArrayItem)dataNode).Index)
{
return Diff3ChangeType.MergeFromAsset2;
}
}
break;
}
return diff3Node.ChangeType;
}
private static void MergeContainer(Diff3Node diff3Node, out object dataInstanceOut)
{
dataInstanceOut = null;
// We don't have a valid parent (probably removed), so skip this node
if (diff3Node.Parent != null && diff3Node.Parent.Asset1Node.Instance == null)
return;
if (diff3Node.Asset1Node == null)
{
diff3Node.Asset1Node = (diff3Node.Asset2Node ?? diff3Node.BaseNode).CreateWithEmptyInstance();
if (diff3Node.Parent != null)
diff3Node.Asset1Node.Parent = diff3Node.Parent.Asset1Node;
}
object dataInstance = diff3Node.Asset1Node.Instance;
// If a node has children, since DiffCollection/DiffDictionary takes null as empty arrays,
// we should now create this array for it to be properly merged
if (dataInstance == null)
dataInstanceOut = dataInstance = Activator.CreateInstance(diff3Node.InstanceType);
// If it's a collection, clear it and reconstruct it from DiffCollection result (stored in Diff3Node.Items)
// TODO: Various optimizations to avoid removing and reinserting items that were already here before (would need to diff Asset1 and Diff3Node...)
var collectionDescriptor = diff3Node.Asset1Node.InstanceDescriptor as CollectionDescriptor;
if (collectionDescriptor != null && diff3Node.Type == Diff3NodeType.Collection)
{
collectionDescriptor.Clear(dataInstance);
if (diff3Node.Items != null)
{
foreach (var item in diff3Node.Items)
{
object itemInstance;
switch (item.ChangeType)
{
case Diff3ChangeType.Children:
case Diff3ChangeType.Conflict:
case Diff3ChangeType.ConflictType:
// Use any valid object, it will be replaced later
itemInstance = SafeNodeInstance(item.Asset1Node) ?? SafeNodeInstance(item.Asset2Node) ?? SafeNodeInstance(item.BaseNode);
break;
case Diff3ChangeType.None:
case Diff3ChangeType.MergeFromAsset1:
case Diff3ChangeType.MergeFromAsset1And2:
itemInstance = item.Asset1Node.Instance;
break;
case Diff3ChangeType.MergeFromAsset2:
itemInstance = item.Asset2Node.Instance;
break;
default:
throw new InvalidOperationException();
}
collectionDescriptor.Add(dataInstance, itemInstance);
}
}
}
}