protected override Provider Visit(CompilableProvider cp)
{
var isPagingProvider = cp.Type.In(ProviderType.Take, ProviderType.Skip, ProviderType.Paging);
if (isPagingProvider && !State.IsSkipTakeChain)
{
var visitedProvider = (CompilableProvider)base.Visit(cp);
var requiresRowNumber = (State.Take != null && !takeSupported) || (State.Skip != null && !skipSupported);
// add rownumber column (if needed)
if (requiresRowNumber)
{
// Arrray to avoid access to modified closure
string[] columnName = { String.Format(Strings.RowNumberX, rowNumberCount++) };
while (visitedProvider.Header.Columns.Any(column => column.Name == columnName[0]))
{
columnName[0] = String.Format(Strings.RowNumberX, rowNumberCount++);
}
visitedProvider = new RowNumberProvider(visitedProvider, columnName[0]);
}
if (State.Take != null && State.Skip != null)
{
visitedProvider = new PagingProvider(visitedProvider, State.Skip, State.Take);
}
else if (State.Take != null)
{
visitedProvider = new TakeProvider(visitedProvider, State.Take);
}
else
{
visitedProvider = new SkipProvider(visitedProvider, State.Skip);
}
// add select removing RowNumber column
if (requiresRowNumber)
{
visitedProvider = new SelectProvider(
visitedProvider,
Enumerable.Range(0, visitedProvider.Header.Length - 1).ToArray());
}
return(visitedProvider);
}
if (!isPagingProvider && State.IsSkipTakeChain)
{
using (State.CreateScope())
return(base.Visit(cp));
}
return(base.Visit(cp));
}
protected override Provider VisitRowNumber(RowNumberProvider provider)
{
var sourceLength = provider.Source.Header.Length;
mappings[provider.Source] = mappings[provider].Where(i => i < sourceLength).ToList();
var newSource = VisitCompilable(provider.Source);
var currentMapping = mappings[provider.Source];
var rowNumberColumn = provider.Header.Columns.Last();
mappings[provider] = Merge(currentMapping, EnumerableUtils.One(rowNumberColumn.Index));
return(newSource == provider.Source
? provider
: new RowNumberProvider(newSource, rowNumberColumn.Name));
}
protected override SqlProvider VisitRowNumber(RowNumberProvider provider)
{
var directionCollection = provider.Header.Order;
if (directionCollection.Count == 0)
{
directionCollection = new DirectionCollection <int>(1);
}
var source = Compile(provider.Source);
var query = ExtractSqlSelect(provider, source);
var rowNumber = SqlDml.RowNumber();
query.Columns.Add(rowNumber, provider.Header.Columns.Last().Name);
var columns = ExtractColumnExpressions(query);
foreach (var order in directionCollection)
{
rowNumber.OrderBy.Add(columns[order.Key], order.Value == Direction.Positive);
}
return(CreateProvider(query, provider, source));
}
/// <summary> /// Compiles <see cref="RowNumberProvider"/>. /// </summary> /// <param name="provider">Row number provider.</param> protected abstract TResult VisitRowNumber(RowNumberProvider provider);
