/// <inheritdoc />
public IEnumerable <IList <IDataItem> > Join(IList <IDataProvider> providers, IList <ICollection <DataBinding> > bindingsPerProvider,
bool includeDynamicItems)
{
// Handle degenerate cases.
int providerCount = providers.Count;
if (providerCount <= 1)
{
return(SequentialJoinStrategy.Instance.Join(providers, bindingsPerProvider, includeDynamicItems));
}
// Get all items from all providers.
var itemLists = new List <IDataItem> [providerCount];
int[] counts = new int[providerCount];
for (int i = 0; i < providerCount; i++)
{
var items = new List <IDataItem>(providers[i].GetItems(bindingsPerProvider[i], includeDynamicItems));
int count = items.Count;
if (count == 0)
{
return(EmptyArray <IList <IDataItem> > .Instance); // there must be at least one value from each provider
}
itemLists[i] = items;
counts[i] = count;
}
var generator = new PairwiseGenerator(counts);
return(GenerateCombinations(generator, itemLists));
}
private static IEnumerable <IList <IDataItem> > GenerateCombinations(PairwiseGenerator generator, List <IDataItem>[] itemLists)
{
int providerCount = itemLists.Length;
int[] indices = new int[providerCount];
while (generator.Next(indices))
{
IDataItem[] combination = new IDataItem[providerCount];
for (int i = 0; i < providerCount; i++)
{
combination[i] = itemLists[i][indices[i]];
}
yield return(combination);
}
}
/// <inheritdoc />
public IEnumerable<IList<IDataItem>> Join(IList<IDataProvider> providers, IList<ICollection<DataBinding>> bindingsPerProvider,
bool includeDynamicItems)
{
// Handle degenerate cases.
int providerCount = providers.Count;
if (providerCount <= 1)
return SequentialJoinStrategy.Instance.Join(providers, bindingsPerProvider, includeDynamicItems);
// Get all items from all providers.
var itemLists = new List<IDataItem>[providerCount];
int[] counts = new int[providerCount];
for (int i = 0; i < providerCount; i++)
{
var items = new List<IDataItem>(providers[i].GetItems(bindingsPerProvider[i], includeDynamicItems));
int count = items.Count;
if (count == 0)
return EmptyArray<IList<IDataItem>>.Instance; // there must be at least one value from each provider
itemLists[i] = items;
counts[i] = count;
}
var generator = new PairwiseGenerator(counts);
return GenerateCombinations(generator, itemLists);
}
private static IEnumerable<IList<IDataItem>> GenerateCombinations(PairwiseGenerator generator, List<IDataItem>[] itemLists)
{
int providerCount = itemLists.Length;
int[] indices = new int[providerCount];
while (generator.Next(indices))
{
IDataItem[] combination = new IDataItem[providerCount];
for (int i = 0; i < providerCount; i++)
combination[i] = itemLists[i][indices[i]];
yield return combination;
}
}
