Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataSet / System / Data / EnumerableRowCollection.cs / 1305376 / EnumerableRowCollection.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //----------------------------------------------------------------------------- using System; using System.Collections.Generic; using System.Collections; using System.Text; using System.Data; using System.Linq; using System.Diagnostics; using System.Linq.Expressions; using System.Collections.ObjectModel; using System.Data.DataSetExtensions; namespace System.Data { ////// Provides an entry point so that Cast operator call can be intercepted within an extension method. /// public abstract class EnumerableRowCollection : IEnumerable { internal abstract Type ElementType { get; } internal abstract DataTable Table { get; } internal EnumerableRowCollection() { } IEnumerator IEnumerable.GetEnumerator() { return null; } } ////// This class provides a wrapper for DataTables to allow for querying via LINQ. /// public class EnumerableRowCollection: EnumerableRowCollection, IEnumerable { private readonly DataTable _table; private readonly IEnumerable _enumerableRows; private readonly List > _listOfPredicates; // Stores list of sort expression in the order provided by user. E.g. order by, thenby, thenby descending.. private readonly SortExpressionBuilder _sortExpression; private readonly Func _selector; #region Properties internal override Type ElementType { get { return typeof(TRow); } } internal IEnumerable EnumerableRows { get { return _enumerableRows; } } internal override DataTable Table { get { return _table; } } #endregion Properties #region Constructors /// /// This constructor is used when Select operator is called with output Type other than input row Type. /// Basically fail on GetLDV(), but other LINQ operators must work. /// internal EnumerableRowCollection(IEnumerableenumerableRows, bool isDataViewable, DataTable table) { Debug.Assert(!isDataViewable || table != null, "isDataViewable bug table is null"); _enumerableRows = enumerableRows; if (isDataViewable) { _table = table; } _listOfPredicates = new List >(); _sortExpression = new SortExpressionBuilder (); } /// /// Basic Constructor /// internal EnumerableRowCollection(DataTable table) { _table = table; _enumerableRows = table.Rows.Cast(); _listOfPredicates = new List >(); _sortExpression = new SortExpressionBuilder (); } /// /// Copy Constructor that sets the input IEnumerable as enumerableRows /// Used to maintain IEnumerable that has linq operators executed in the same order as the user /// internal EnumerableRowCollection(EnumerableRowCollectionsource, IEnumerable enumerableRows, Func selector) { Debug.Assert(null != enumerableRows, "null enumerableRows"); _enumerableRows = enumerableRows; _selector = selector; if (null != source) { if (null == source._selector) { _table = source._table; } _listOfPredicates = new List >(source._listOfPredicates); _sortExpression = source._sortExpression.Clone(); //deep copy the List } else { _listOfPredicates = new List >(); _sortExpression = new SortExpressionBuilder (); } } #endregion Constructors #region PublicInterface IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); } /// /// This method returns an strongly typed iterator /// for the underlying DataRow collection. /// ////// A strongly typed iterator. /// public IEnumeratorGetEnumerator() { return _enumerableRows.GetEnumerator(); } #endregion PublicInterface /// /// Evaluates filter and sort if necessary and returns /// a LinqDataView representing the LINQ query this class has collected. /// ///LinqDataView repesenting the LINQ query internal LinqDataView GetLinqDataView() //Called by AsLinqDataView { if ((null == _table) || !typeof(DataRow).IsAssignableFrom(typeof(TRow))) { throw DataSetUtil.NotSupported(Strings.ToLDVUnsupported); } LinqDataView view = null; #region BuildSinglePredicate FuncfinalPredicate = null; //Conjunction of all .Where(..) predicates if ((null != _selector) && (0 < _listOfPredicates.Count)) { // Hook up all individual predicates into one predicate // This delegate is a conjunction of multiple predicates set by the user // Note: This is a Short-Circuit Conjunction finalPredicate = delegate(DataRow row) { if (!Object.ReferenceEquals(row, _selector((TRow)(object)row))) { throw DataSetUtil.NotSupported(Strings.ToLDVUnsupported); } foreach (Func pred in _listOfPredicates) { if (!pred((TRow)(object)row)) { return false; } } return true; }; } else if (null != _selector) { finalPredicate = delegate(DataRow row) { if (!Object.ReferenceEquals(row, _selector((TRow)(object)row))) { throw DataSetUtil.NotSupported(Strings.ToLDVUnsupported); } return true; }; } else if (0 < _listOfPredicates.Count) { finalPredicate = delegate(DataRow row) { foreach (Func pred in _listOfPredicates) { if (!pred((TRow)(object)row)) { return false; } } return true; }; } #endregion BuildSinglePredicate #region Evaluate Filter/Sort // All of this mess below is because we want to create index only once. // // If we only have filter, we set _view.Predicate - 1 index creation // If we only have sort, we set _view.SortExpression() - 1 index creation // If we have BOTH, we set them through the constructor - 1 index creation // // Filter AND Sort if ((null != finalPredicate) && (0 < _sortExpression.Count)) { // A lot more work here because constructor does not know type K, // so the responsibility to create appropriate delegate comparers // is outside of the constructor. view = new LinqDataView( _table, finalPredicate, //Func() Predicate delegate(DataRow row) //System.Predicate { return finalPredicate(row); }, delegate(DataRow a, DataRow b) //Comparison for DV for Index creation { return _sortExpression.Compare( _sortExpression.Select((TRow)(object)a), _sortExpression.Select((TRow)(object)b) ); }, delegate(object key, DataRow row) //Comparison_K_T for DV's Find() { return _sortExpression.Compare( (List
Link Menu

This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- ColorInterpolationModeValidation.cs
- ReadWriteObjectLock.cs
- WinInetCache.cs
- LoginUtil.cs
- BitConverter.cs
- DbSource.cs
- DbCommandDefinition.cs
- MetadataItem.cs
- WsdlBuildProvider.cs
- TransformedBitmap.cs
- ResXDataNode.cs
- ConfigXmlDocument.cs
- sqlmetadatafactory.cs
- AppendHelper.cs
- TextSpan.cs
- ListMarkerLine.cs
- FontUnitConverter.cs
- Literal.cs
- OracleBoolean.cs
- sqlinternaltransaction.cs
- TransformerConfigurationWizardBase.cs
- XPathNodePointer.cs
- DBParameter.cs
- SqlRewriteScalarSubqueries.cs
- NestPullup.cs
- InputDevice.cs
- StateRuntime.cs
- SqlCacheDependency.cs
- WindowsRichEdit.cs
- MD5Cng.cs
- ByteStreamGeometryContext.cs
- TextComposition.cs
- Transform.cs
- BaseServiceProvider.cs
- RewritingSimplifier.cs
- Expressions.cs
- WsatAdminException.cs
- XamlNamespaceHelper.cs
- Transform.cs
- QueuedDeliveryRequirementsMode.cs
- basenumberconverter.cs
- EncryptedXml.cs
- ValidationHelper.cs
- PasswordTextNavigator.cs
- ProvideValueServiceProvider.cs
- MenuItemBindingCollection.cs
- LineSegment.cs
- WebHttpDispatchOperationSelector.cs
- PerformanceCounters.cs
- XPathException.cs
- StreamMarshaler.cs
- EtwProvider.cs
- XmlUtilWriter.cs
- EditorServiceContext.cs
- DateTimeUtil.cs
- EditorPartCollection.cs
- TextCompositionManager.cs
- DocumentEventArgs.cs
- ExpandCollapseProviderWrapper.cs
- DataView.cs
- IntSumAggregationOperator.cs
- streamingZipPartStream.cs
- ZipFileInfoCollection.cs
- StylusDownEventArgs.cs
- Transform.cs
- ShutDownListener.cs
- CheckBoxFlatAdapter.cs
- MenuItem.cs
- Size.cs
- XmlChildEnumerator.cs
- DynamicHyperLink.cs
- ContractReference.cs
- Registry.cs
- Assert.cs
- ClipboardProcessor.cs
- ApplicationActivator.cs
- basemetadatamappingvisitor.cs
- CategoryEditor.cs
- DataControlImageButton.cs
- MouseBinding.cs
- IOException.cs
- HttpProfileBase.cs
- DesignOnlyAttribute.cs
- AttributeProviderAttribute.cs
- WebPartsSection.cs
- XmlNodeChangedEventArgs.cs
- SwitchLevelAttribute.cs
- SignatureToken.cs
- KeyEventArgs.cs
- PartialTrustHelpers.cs
- DBNull.cs
- OpacityConverter.cs
- KeyNotFoundException.cs
- ConfigurationPermission.cs
- TextureBrush.cs
- TypeHelpers.cs
- ToolStripPanelRenderEventArgs.cs
- Style.cs
- XsdCachingReader.cs
- DropShadowEffect.cs