protected override Provider VisitSkip(SkipProvider provider)
{
State.IsSkipTakeChain = true;
var visitedSource = VisitCompilable(provider.Source);
State.AddSkip(provider.Count);
return(visitedSource);
}
protected override Provider VisitSkip(SkipProvider provider)
{
var source = VisitCompilable(provider.Source);
EnsureAbsenceOfApplyProviderRequiringConversion();
if (source != provider.Source)
{
return(new SkipProvider(source, provider.Count));
}
return(provider);
}
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));
}
/// <inheritdoc/>
protected override SqlProvider VisitSkip(SkipProvider provider)
{
if (providerInfo.Supports(ProviderFeatures.NativeSkip))
{
return(VisitPagingNative(provider, null, provider.Count));
}
if (providerInfo.Supports(ProviderFeatures.RowNumber))
{
return(VisitSkipRowNumber(provider));
}
throw new NotSupportedException(string.Format(Strings.ExXIsNotSupported, "Skip"));
}
private SqlProvider VisitSkipRowNumber(SkipProvider provider)
{
var skipParameterBinding = CreateLimitOffsetParameterBinding(provider.Count);
var bindings = new List <QueryParameterBinding> {
skipParameterBinding
};
var compiledSource = Compile(provider.Source);
var source = compiledSource.Request.Statement;
var queryRef = SqlDml.QueryRef(source);
var query = SqlDml.Select(queryRef);
query.Columns.AddRange(queryRef.Columns.Cast <SqlColumn>());
query.Where = queryRef.Columns.Last() > skipParameterBinding.ParameterReference;
return(CreateProvider(query, bindings, provider, compiledSource));
}
/// <summary> /// Compiles <see cref="SkipProvider"/>. /// </summary> /// <param name="provider">Skip provider.</param> protected abstract TResult VisitSkip(SkipProvider provider);
