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/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Objects / Internal / ObjectQueryState.cs / 1599186 / ObjectQueryState.cs
//---------------------------------------------------------------------- //// Copyright (c) Microsoft Corporation. All rights reserved. // // // @owner [....] //--------------------------------------------------------------------- namespace System.Data.Objects.Internal { using System; using System.Collections.Generic; using System.Data.Common; using System.Data.Common.CommandTrees; using System.Data.Common.EntitySql; using System.Data.EntityClient; using System.Data.Metadata.Edm; using System.Data.Objects; using System.Data.Objects.DataClasses; using System.Diagnostics; using System.Globalization; using System.Reflection; using System.Data.Objects.ELinq; using System.Runtime.CompilerServices; ////// An instance of a class derived from ObjectQueryState is used to model every instance of internal abstract class ObjectQueryState { ///. /// A different ObjectQueryState-derived class is used depending on whether the ObjectQuery is an Entity SQL, /// Linq to Entities, or compiled Linq to Entities query. /// /// The internal static readonly MergeOption DefaultMergeOption = MergeOption.AppendOnly; ///that should be used in the absence of an explicitly specified /// or user-specified merge option or a merge option inferred from the query definition itself. /// /// The context of the ObjectQuery /// private readonly ObjectContext _context; ////// The element type of this query, as a CLR type /// private readonly Type _elementType; ////// The collection of parameters associated with the ObjectQuery /// private ObjectParameterCollection _parameters; ////// The full-span specification /// private Span _span; ////// The user-specified default merge option /// private MergeOption? _userMergeOption; ////// Indicates whether query caching is enabled for the implemented ObjectQuery. /// private bool _cachingEnabled; ////// Optionally used by derived classes to record the most recently used protected ObjectQueryExecutionPlan _cachedPlan; ///. /// /// Constructs a new ObjectQueryImplementation that uses the specified context and parameters collection. /// /// /// The ObjectContext to which the implemented ObjectQuery belongs /// protected ObjectQueryState(Type elementType, ObjectContext context, ObjectParameterCollection parameters, Span span) { // Validate the element type EntityUtil.CheckArgumentNull(elementType, "elementType"); // Validate the context EntityUtil.CheckArgumentNull(context, "context"); // Parameters and Span are specifically allowed to be null this._elementType = elementType; this._context = context; this._span = span; this._parameters = parameters; } ////// Gets the element type - the type of each result item - for this query as a CLR type instance. /// internal Type ElementType { get { return _elementType; } } ////// Gets the ObjectContext with which the implemented ObjectQuery is associated /// internal ObjectContext ObjectContext { get { return _context; } } ////// Gets the collection of parameters associated with the implemented ObjectQuery. May be null. /// Call internal ObjectParameterCollection Parameters { get { return _parameters; } } internal ObjectParameterCollection EnsureParameters() { if (_parameters == null) { _parameters = new ObjectParameterCollection(ObjectContext.Perspective); if (this._cachedPlan != null) { _parameters.SetReadOnly(true); } } return _parameters; } ///if a guaranteed non-null collection is required. /// /// Gets the Span specification associated with the implemented ObjectQuery. May be null. /// internal Span Span { get { return _span; } } ////// The merge option that this query considers currently 'in effect'. This may be a merge option set via the ObjectQuery.MergeOption /// property, or the merge option that applies to the currently cached execution plan, if any, or the global default merge option. /// internal MergeOption EffectiveMergeOption { get { if (_userMergeOption.HasValue) { return _userMergeOption.Value; } ObjectQueryExecutionPlan plan = this._cachedPlan; if (plan != null) { return plan.MergeOption; } return ObjectQueryState.DefaultMergeOption; } } ////// Gets or sets a value indicating which internal MergeOption? UserSpecifiedMergeOption { get { return _userMergeOption; } set { _userMergeOption = value; } } ///should be used when preparing this query for execution via /// if no option is explicitly specified - for example during foreach-style enumeration. /// sets this property on its underlying query state instance. /// /// Gets or sets a value indicating whether or not query caching is enabled for the imlemented ObjectQuery. /// internal bool PlanCachingEnabled { get { return _cachingEnabled; } set { _cachingEnabled = value; } } ////// Gets the result type - not just the element type - for this query as an EDM Type usage instance. /// internal TypeUsage ResultType { get { ObjectQueryExecutionPlan plan = this._cachedPlan; if (plan != null) { return plan.ResultType; } else { return this.GetResultType(); } } } ////// Sets the values the /// The query state to which this instances settings should be applied. internal void ApplySettingsTo(ObjectQueryState other) { other.PlanCachingEnabled = this.PlanCachingEnabled; other.UserSpecifiedMergeOption = this.UserSpecifiedMergeOption; // _cachedPlan is intentionally not copied over - since the parameters of 'other' would have to be locked as // soon as its execution plan was set, and that may not be appropriate at the time ApplySettingsTo is called. } ///and properties on /// to match the values of the corresponding properties on this instance. /// /// Must return /// The command text of this query, if available. ///true and setto a valid value /// if command text is available for this query; must return false otherwise. /// Implementations of this method must not throw exceptions. ///internal abstract bool TryGetCommandText(out string commandText); /// true if command text is available for this query and was successfully retrieved; otherwisefalse ./// Must return /// The LINQ Expression that defines this query, if available. ///true and setto a valid value if a /// LINQ Expression is available for this query; must return false otherwise. /// Implementations of this method must not throw exceptions. ///internal abstract bool TryGetExpression(out System.Linq.Expressions.Expression expression); /// true if an Expression is available for this query and was successfully retrieved; otherwisefalse ./// Retrieves an /// The merge option which should be supported by the returned execution plan ///that can be used to retrieve the results of this query using the specified merge option. /// If is null, an appropriate default value will be used. /// an execution plan capable of retrieving the results of this query using the specified merge option internal abstract ObjectQueryExecutionPlan GetExecutionPlan(MergeOption? forMergeOption); ////// Must returns a new ObjectQueryState instance that is a duplicate of this instance and additionally contains the specified Include path in its ///. /// The element type of the source query on which Include was called /// The source query on which Include was called /// The new Include path to add ///Must returns an ObjectQueryState that is a duplicate of this instance and additionally contains the specified Include path internal abstract ObjectQueryState Include(ObjectQuery sourceQuery, string includePath); /// /// Retrieves the result type of the query in terms of C-Space metadata. This method is called once, on-demand, if a call /// to ///cannot be satisfied using cached type metadata or a currently cached execution plan. /// /// Must return a protected abstract TypeUsage GetResultType(); ///that describes the result typeof this query in terms of C-Space metadata /// /// Helper method to return the first non-null merge option from the specified nullable merge options, /// or the /// The available nullable merge option values, in order of decreasing preference ///if the value of all specified nullable merge options is null . ///the first non-null merge option; or the default merge option if the value of all protected static MergeOption EnsureMergeOption(params MergeOption?[] preferredMergeOptions) { foreach (MergeOption? preferred in preferredMergeOptions) { if (preferred.HasValue) { return preferred.Value; } } return ObjectQueryState.DefaultMergeOption; } ///is null /// Helper method to return the first non-null merge option from the specified nullable merge options. /// /// The available nullable merge option values, in order of decreasing preference ///the first non-null merge option; or protected static MergeOption? GetMergeOption(params MergeOption?[] preferredMergeOptions) { foreach (MergeOption? preferred in preferredMergeOptions) { if (preferred.HasValue) { return preferred.Value; } } return null; } ///null if the value of allis null /// Helper method to create a new ObjectQuery based on this query state instance. /// ///A new [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.NoOptimization)] internal ObjectQuery CreateQuery() { MethodInfo createMethod = typeof(ObjectQueryState).GetMethod("CreateObjectQuery", BindingFlags.Static | BindingFlags.Public); Debug.Assert(createMethod != null, "Unable to retrieve ObjectQueryState.CreateObjectQuery<> method?"); createMethod = createMethod.MakeGenericMethod(this._elementType); return (ObjectQuery)createMethod.Invoke(null, new object[] { this } ); } ///- typed as /// Helper method used to create an ObjectQuery based on an underlying ObjectQueryState instance. /// Although not called directly, this method must be public to be reliably callable from ///using reflection. /// The required element type of the new ObjectQuery /// The underlying ObjectQueryState instance that should back the returned ObjectQuery ///A new ObjectQuery based on the specified query state, with the specified element type public static ObjectQueryCreateObjectQuery (ObjectQueryState queryState) { Debug.Assert(queryState != null, "Query state is required"); Debug.Assert(typeof(TResultType) == queryState.ElementType, "Element type mismatch"); return new ObjectQuery (queryState); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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