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/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Common / internal / materialization / coordinatorfactory.cs / 1305376 / coordinatorfactory.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //----------------------------------------------------------------------------- using System.Collections.Generic; using System.Diagnostics; using System.Linq; using System.Linq.Expressions; using System.Text; using System.Data.Objects.Internal; namespace System.Data.Common.Internal.Materialization { ////// An immutable class used to generate new coordinators. These coordinators are used /// at runtime to materialize results. /// internal abstract class CoordinatorFactory { #region statics ////// Function of shaper that returns true; one default case when there is no explicit predicate. /// private static readonly FuncAlwaysTrue = s => true; /// /// Function of shaper that returns false; one default case used when there is no explicit predicate. /// private static readonly FuncAlwaysFalse = s => false; #endregion #region state /// /// Gets depth of the reader (0 is top-level -- which incidentally doesn't /// require a coordinator... /// internal readonly int Depth; ////// Indicates which state slot in the Shaper.State is expected to hold the /// value for this nested reader result. /// internal readonly int StateSlot; ////// A function determining whether the current row has data for this nested result. /// internal readonly FuncHasData; /// /// A function setting key values. (the return value is irrelevant) /// internal readonly FuncSetKeys; /// /// A function returning true if key values match the previously set values. /// internal readonly FuncCheckKeys; /// /// Nested results below this (at depth + 1) /// internal readonly System.Collections.ObjectModel.ReadOnlyCollectionNestedCoordinators; /// /// Indicates whether this is a leaf reader. /// internal readonly bool IsLeafResult; ////// Indicates whether this coordinator can be managed by a simple enumerator. A simple enumerator /// returns a single element per row, so the following conditions disqualify the enumerator: /// nested collections, data discriminators (not all rows have data), keys (not all rows have new data). /// internal readonly bool IsSimple; ////// For value-layer queries, the factories for all the records that we can potentially process /// at this level in the query result. /// internal readonly System.Collections.ObjectModel.ReadOnlyCollectionRecordStateFactories; #endregion #region constructor protected CoordinatorFactory(int depth, int stateSlot, Func hasData, Func setKeys, Func checkKeys, CoordinatorFactory[] nestedCoordinators, RecordStateFactory[] recordStateFactories) { this.Depth = depth; this.StateSlot = stateSlot; // figure out if there are any nested coordinators this.IsLeafResult = 0 == nestedCoordinators.Length; // if there is no explicit 'has data' discriminator, it means all rows contain data for the coordinator if (hasData == null) { this.HasData = AlwaysTrue; } else { this.HasData = hasData; } // if there is no explicit set key delegate, just return true (the value is not used anyways) if (setKeys == null) { this.SetKeys = AlwaysTrue; } else { this.SetKeys = setKeys; } // If there are no keys, it means different things depending on whether we are a leaf // coordinator or an inner (or 'driving') coordinator. For a leaf coordinator, it means // that every row is a new result. For an inner coordinator, it means that there is no // key to check. This should only occur where there is a SingleRowTable (in other words, // all rows are elements of a single child collection). if (checkKeys == null) { if (this.IsLeafResult) { this.CheckKeys = AlwaysFalse; // every row is a new result (the keys don't match) } else { this.CheckKeys = AlwaysTrue; // every row belongs to a single child collection } } else { this.CheckKeys = checkKeys; } this.NestedCoordinators = new System.Collections.ObjectModel.ReadOnlyCollection (nestedCoordinators); this.RecordStateFactories = new System.Collections.ObjectModel.ReadOnlyCollection (recordStateFactories); // Determines whether this coordinator can be handled by a 'simple' enumerator. See IsSimple for details. this.IsSimple = IsLeafResult && null == checkKeys && null == hasData; } #endregion #region "public" surface area /// /// Creates a buffer handling state needed by this coordinator. /// internal abstract Coordinator CreateCoordinator(Coordinator parent, Coordinator next); #endregion } ////// Typed internal sealed class CoordinatorFactory/// : CoordinatorFactory { #region state /// /// Reads a single element of the result from the given reader state object, returning the /// result as a wrapped entity. May be null if the element is not available as a wrapped entity. /// internal readonly FuncWrappedElement; /// /// Reads a single element of the result from the given reader state object. /// May be null if the element is available as a wrapped entity instead. /// internal readonly FuncElement; /// /// Same as Element but uses slower patterns to provide better exception messages (e.g. /// using reader.GetValue + type check rather than reader.GetInt32) /// internal readonly FuncElementWithErrorHandling; /// /// Initializes the collection storing results from this coordinator. /// internal readonly Func> InitializeCollection; /// /// Description of this CoordinatorFactory, used for debugging only; while this is not /// needed in retail code, it is pretty important because it's the only description we'll /// have once we compile the Expressions; debugging a problem with retail bits would be /// pretty hard without this. /// private readonly string Description; #endregion #region constructor public CoordinatorFactory(int depth, int stateSlot, Expression hasData, Expression setKeys, Expression checkKeys, CoordinatorFactory[] nestedCoordinators, Expression element, Expression elementWithErrorHandling, Expression initializeCollection, RecordStateFactory[] recordStateFactories) : base(depth, stateSlot, CompilePredicate(hasData), CompilePredicate(setKeys), CompilePredicate(checkKeys), nestedCoordinators, recordStateFactories) { // If we are in a case where a wrapped entity is available, then use it; otherwise use the raw element. // However, in both cases, use the raw element for the error handling case where what we care about is // getting the appropriate exception message. if (typeof(IEntityWrapper).IsAssignableFrom(element.Type)) { this.WrappedElement = Translator.Compile(element); elementWithErrorHandling = Translator.Emit_UnwrapAndEnsureType(elementWithErrorHandling, typeof(TElement)); } else { this.Element = Translator.Compile (element); } this.ElementWithErrorHandling = Translator.Compile (elementWithErrorHandling); this.InitializeCollection = null == initializeCollection ? s => new List () : Translator.Compile >(initializeCollection); this.Description = new StringBuilder() .Append("HasData: ") .AppendLine(DescribeExpression(hasData)) .Append("SetKeys: ") .AppendLine(DescribeExpression(setKeys)) .Append("CheckKeys: ") .AppendLine(DescribeExpression(checkKeys)) .Append("Element: ") .AppendLine(DescribeExpression(element)) .Append("ElementWithExceptionHandling: ") .AppendLine(DescribeExpression(elementWithErrorHandling)) .Append("InitializeCollection: ") .AppendLine(DescribeExpression(initializeCollection)) .ToString(); } #endregion #region expression helpers /// /// Return the compiled expression for the predicate /// private static FuncCompilePredicate(Expression predicate) { Func result; if (null == predicate) { result = null; } else { result = Translator.Compile (predicate); } return result; } /// /// Returns a string representation of the expression /// private static string DescribeExpression(Expression expression) { string result; if (null == expression) { result = "undefined"; } else { result = expression.ToString(); } return result; } #endregion #region "public" surface area ////// Create a coordinator used for materialization of collections. Unlike the CoordinatorFactory, /// the Coordinator contains mutable state. /// internal override Coordinator CreateCoordinator(Coordinator parent, Coordinator next) { return new Coordinator(this, parent, next); } /// /// Returns the "default" record state (that is, the one we use for PreRead/PastEnd reader states /// internal RecordState GetDefaultRecordState(Shapershaper) { RecordState result = null; if (this.RecordStateFactories.Count > 0) { // result = (RecordState)shaper.State[this.RecordStateFactories[0].StateSlotNumber]; Debug.Assert(null != result, "did you initialize the record states?"); result.ResetToDefaultState(); } return result; } public override string ToString() { return Description; } #endregion } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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