///<summary>Binds this selection to a collection of data. This creates a new selection with Enter and Exit selections, which can then be used to create missing elements and/or delete excess elements.</summary>
///<remarks>In a typical case, you would use <see href="Selection{E,T}.Join{T2}" />Join function, which handles Enter and Exit selections for you.</remarks>
///<param name="bindingFunc">A callback function that is called once for each group, and should provide the data collection for this group. It's parameters are parent's data object and the collection of elements.</param>
public Selection <TElementType, TNewDataType, TParentDataType> Bind <TNewDataType>(Func <object, IReadOnlyCollection <TElementType>, IEnumerable <TNewDataType> > bindingFunc)
{
var enters = new EnterSelection <TNewDataType, TParentDataType> .EnterGroup[_groups.Count];
var updates = new Selection <TElementType, TNewDataType, TParentDataType> .GroupWithData[_groups.Count];
var exits = new Selection <TElementType, TNewDataType, TParentDataType> .GroupWithData[_groups.Count];
int counter = 0;
foreach (var groupWithData in _groups)
{
var tuple = Bind(groupWithData, bindingFunc(groupWithData.GroupParent.GetBoundData(), groupWithData.Elements));
enters[counter] = tuple.Item1;
updates[counter] = tuple.Item2;
exits[counter] = tuple.Item3;
counter++;
}
var enterSelection = new EnterSelection <TNewDataType, TParentDataType>(enters);
var exitSelection = new Selection <TElementType, TNewDataType, TParentDataType>(exits);
return(new Selection <TElementType, TNewDataType, TParentDataType>(updates, enterSelection, exitSelection));
}
internal Selection(IReadOnlyCollection <GroupWithData> groups, EnterSelection <TDataType, TParentDataType> enter, Selection <TElementType, TDataType, TParentDataType> exit)
{
_groups = groups;
_enterSelection = enter;
_exitSelection = exit;
}
internal Selection(IReadOnlyCollection <GroupWithData> groups)
{
_groups = groups;
_enterSelection = null;
_exitSelection = null;
}
///<summary>Creates a selection from a read-only collection. The collection is not copied, so Selection expects it not to change during it's existence.</summary>
public Selection(IReadOnlyCollection <TElementType> selected)
{
_groups = new [] { new GroupWithData(null, selected) };
_enterSelection = null;
_exitSelection = null;
}