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/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Objects / ELinq / ELinqQueryState.cs / 1305376 / ELinqQueryState.cs
//---------------------------------------------------------------------- //// Copyright (c) Microsoft Corporation. All rights reserved. // // // @owner [....] // @backupOwner [....] //--------------------------------------------------------------------- namespace System.Data.Objects.ELinq { using System; using System.Collections.Generic; using System.Data.Common.CommandTrees; using System.Data.Metadata.Edm; using System.Data.Objects; using System.Data.Objects.ELinq; using System.Data.Objects.Internal; using System.Diagnostics; using System.Reflection; using System.Linq; using System.Linq.Expressions; using System.Collections.ObjectModel; ////// Models a Linq to Entities ObjectQuery /// internal class ELinqQueryState : ObjectQueryState { #region Private State private readonly Expression _expression; private Func_recompileRequired; private ReadOnlyCollection > _linqParameters; #endregion #region Constructors /// /// Constructs a new ELinqQueryImplementation based on the specified Linq Expression /// against the specified ObjectContext. /// /// The element type of the implemented ObjectQuery, as a CLR type. /// The ObjectContext with which the implemented ObjectQuery is associated. /// The Linq Expression that defines this query. internal ELinqQueryState(Type elementType, ObjectContext context, Expression expression) : base(elementType, context, null, null) { // // Initialize the LINQ expression, which is passed in via // public APIs on ObjectQuery and must be checked here // (the base class performs similar checks on the ObjectContext and MergeOption arguments). // EntityUtil.CheckArgumentNull(expression, "expression"); // closure bindings and initializers are explicitly allowed to be null _expression = expression; } #endregion #region ObjectQueryState overrides protected override TypeUsage GetResultType() { // Since this method is only called once, on demand, a full conversion pass // is performed to produce the DbExpression and return its result type. // This does not affect any cached execution plan or closure bindings that may be present. ExpressionConverter converter = this.CreateExpressionConverter(); return converter.Convert().ResultType; } internal override ObjectQueryExecutionPlan GetExecutionPlan(MergeOption? forMergeOption) { Debug.Assert(this.Span == null, "Include span specified on compiled LINQ-based ObjectQuery instead of within the expression tree?"); // If this query has already been prepared, its current execution plan may no longer be valid. ObjectQueryExecutionPlan plan = this._cachedPlan; if (plan != null) { // Was a merge option specified in the call to Execute(MergeOption) or set via ObjectQuery.MergeOption? MergeOption? explicitMergeOption = GetMergeOption(forMergeOption, this.UserSpecifiedMergeOption); // If a merge option was explicitly specified, and it does not match the plan's merge option, then the plan is no longer valid. if((explicitMergeOption.HasValue && explicitMergeOption.Value != plan.MergeOption) || this._recompileRequired()) { plan = null; } } // The plan may have been invalidated above, or this query may never have been prepared. if (plan == null) { // Metadata is required to generate the execution plan. this.ObjectContext.EnsureMetadata(); // Reset internal state this._recompileRequired = null; this.ResetParameters(); // Translate LINQ expression to a DbExpression ExpressionConverter converter = this.CreateExpressionConverter(); DbExpression queryExpression = converter.Convert(); // This delegate tells us when a part of the expression tree has changed requiring a recompile. this._recompileRequired = converter.RecompileRequired; // Determine the merge option, with the following precedence: // 1. A merge option was specified explicitly as the argument to Execute(MergeOption). // 2. The user has set the MergeOption property on the ObjectQuery instance. // 3. A merge option has been extracted from the 'root' query and propagated to the root of the expression tree. // 4. The global default merge option. MergeOption mergeOption = EnsureMergeOption(forMergeOption, this.UserSpecifiedMergeOption, converter.PropagatedMergeOption); // If parameters were aggregated from referenced (non-LINQ) ObjectQuery instances then add them to the parameters collection _linqParameters = converter.GetParameters(); if (_linqParameters != null && _linqParameters.Count > 0) { ObjectParameterCollection currentParams = this.EnsureParameters(); currentParams.SetReadOnly(false); foreach (KeyValuePairpair in _linqParameters) { // Note that it is safe to add the parameter directly only // because parameters are cloned before they are added to the // converter's parameter collection, or they came from this // instance's parameter collection in the first place. ObjectParameter convertedParam = pair.Key; currentParams.Add(convertedParam); } currentParams.SetReadOnly(true); } DbQueryCommandTree tree = DbQueryCommandTree.FromValidExpression(this.ObjectContext.MetadataWorkspace, DataSpace.CSpace, queryExpression); plan = ObjectQueryExecutionPlan.Prepare(this.ObjectContext, tree, this.ElementType, mergeOption, converter.PropagatedSpan, null); this._cachedPlan = plan; } if (_linqParameters != null) { foreach (KeyValuePair pair in _linqParameters) { ObjectParameter parameter = pair.Key; QueryParameterExpression parameterExpression = pair.Value; if (null != parameterExpression) { parameter.Value = parameterExpression.EvaluateParameter(null); } } } return plan; } /// /// Returns a new ObjectQueryState instance with the specified navigation property path specified as an Include span. /// For eLINQ queries the Include operation is modelled as a method call expression applied to the source ObectQuery, /// so the ///property is always null on the returned instance. ///The element type of the resulting query /// The ObjectQuery on which Include was called; required to build the new method call expression /// The new Include path ///A new ObjectQueryState instance that incorporates the Include path, in this case a new method call expression internal override ObjectQueryState Include(ObjectQuery sourceQuery, string includePath) { MethodInfo includeMethod = sourceQuery.GetType().GetMethod("Include", BindingFlags.Public | BindingFlags.Instance); Debug.Assert(includeMethod != null, "Unable to find ObjectQuery.Include method?"); Expression includeCall = Expression.Call(Expression.Constant(sourceQuery), includeMethod, new Expression[] { Expression.Constant(includePath, typeof(string)) }); ObjectQueryState retState = new ELinqQueryState(this.ElementType, this.ObjectContext, includeCall); this.ApplySettingsTo(retState); return retState; } /// /// eLINQ queries do not have command text. This method always returns /// Always set tofalse . ///null ///Always returns internal override bool TryGetCommandText(out string commandText) { commandText = null; return false; } ///false /// Gets the LINQ Expression that defines this query for external (of ObjectQueryState) use. /// Note that the /// The LINQ expression that describes this query ///property is used, which is overridden by compiled eLINQ /// queries to produce an Expression tree where parameter references have been replaced with constants. /// Always returns internal override bool TryGetExpression(out System.Linq.Expressions.Expression expression) { expression = this.Expression; return true; } #endregion internal virtual Expression Expression { get { return _expression; } } protected virtual ExpressionConverter CreateExpressionConverter() { Funcletizer funcletizer = Funcletizer.CreateQueryFuncletizer(this.ObjectContext); return new ExpressionConverter(funcletizer, _expression); } private void ResetParameters() { if (this.Parameters != null) { bool wasLocked = ((ICollectiontrue )this.Parameters).IsReadOnly; if (wasLocked) { this.Parameters.SetReadOnly(false); } this.Parameters.Clear(); if (wasLocked) { this.Parameters.SetReadOnly(true); } } _linqParameters = null; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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