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
- TriggerAction.cs
- XmlSchemaImporter.cs
- WinEventTracker.cs
- GlyphRunDrawing.cs
- TextSelection.cs
- EntityWrapper.cs
- HatchBrush.cs
- HtmlProps.cs
- DiffuseMaterial.cs
- MessageQueueInstaller.cs
- PaintEvent.cs
- PowerStatus.cs
- ReadonlyMessageFilter.cs
- ErrorLog.cs
- EntityDataReader.cs
- HtmlLabelAdapter.cs
- TextEndOfParagraph.cs
- SapiInterop.cs
- BaseDataList.cs
- SchemaElementLookUpTable.cs
- DrawingGroupDrawingContext.cs
- MouseGestureConverter.cs
- StringConcat.cs
- ObjectViewEntityCollectionData.cs
- TextBounds.cs
- DataServiceQueryProvider.cs
- XmlAttributes.cs
- XmlTextReader.cs
- NumericUpDownAccelerationCollection.cs
- EDesignUtil.cs
- BuildResult.cs
- FixedSOMElement.cs
- SessionStateModule.cs
- AnnotationResource.cs
- SourceFileInfo.cs
- PolicyStatement.cs
- ObjectDisposedException.cs
- PolygonHotSpot.cs
- EventBindingService.cs
- Compiler.cs
- glyphs.cs
- figurelength.cs
- FormatVersion.cs
- DesignerWithHeader.cs
- ImageMetadata.cs
- _ReceiveMessageOverlappedAsyncResult.cs
- CodeCommentStatement.cs
- BinaryFormatterWriter.cs
- HandledEventArgs.cs
- FixedSOMPageConstructor.cs
- SMSvcHost.cs
- WSFederationHttpBindingCollectionElement.cs
- DbConnectionStringCommon.cs
- SetUserPreferenceRequest.cs
- SizeAnimationUsingKeyFrames.cs
- ContainerUIElement3D.cs
- WmlCalendarAdapter.cs
- WebPartDisplayModeEventArgs.cs
- RequestStatusBarUpdateEventArgs.cs
- IdentityModelStringsVersion1.cs
- AssemblySettingAttributes.cs
- FileDetails.cs
- GeometryDrawing.cs
- PageAsyncTaskManager.cs
- XmlImplementation.cs
- QueueAccessMode.cs
- RawStylusSystemGestureInputReport.cs
- AutomationElementCollection.cs
- PanelDesigner.cs
- While.cs
- DockAndAnchorLayout.cs
- PictureBox.cs
- AppSettings.cs
- SmtpReplyReader.cs
- System.Data_BID.cs
- querybuilder.cs
- StringDictionary.cs
- ClientType.cs
- TextPatternIdentifiers.cs
- LocalizableResourceBuilder.cs
- FormViewPagerRow.cs
- FrameworkContentElementAutomationPeer.cs
- WhitespaceRule.cs
- Lease.cs
- ModelVisual3D.cs
- ValidatedControlConverter.cs
- designeractionbehavior.cs
- QueryableDataSourceEditData.cs
- MessageHeader.cs
- OptionUsage.cs
- MergeFailedEvent.cs
- COAUTHIDENTITY.cs
- StreamReader.cs
- DataTemplate.cs
- ServiceOperationInvoker.cs
- NetSectionGroup.cs
- SpeakProgressEventArgs.cs
- PropertyPathConverter.cs
- ContentAlignmentEditor.cs
- BinaryObjectWriter.cs