ObjectQueryState.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / Orcas / NetFXw7 / ndp / fx / src / DataEntity / System / Data / Objects / Internal / ObjectQueryState.cs / 1 / 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; 

    ///  
    ///   An instance of a class derived from ObjectQueryState is used to model every instance of . 
    ///   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. 
    /// 
    internal abstract class ObjectQueryState
    {
        ///  
        ///   The  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. 
        ///  
        internal static readonly MergeOption DefaultMergeOption = MergeOption.AppendOnly;
 
        /// 
        ///   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  if a guaranteed non-null collection is required.
        ///  
        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;
        } 

        /// 
        ///   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  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. 
        /// 
        internal MergeOption? UserSpecifiedMergeOption
        {
            get { return _userMergeOption; } 
            set { _userMergeOption = value; }
        } 
 
        /// 
        ///   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  and  properties on
        ///    to match the values of the corresponding properties on this instance.
        /// 
        /// 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.
        }
 
        /// 
        ///   Must return true and set  to a valid value 
        ///   if command text is available for this query; must return false otherwise. 
        ///   Implementations of this method must not throw exceptions.
        ///  
        /// The command text of this query, if available.
        /// true if command text is available for this query and was successfully retrieved; otherwise false.
        internal abstract bool TryGetCommandText(out string commandText);
 
        /// 
        ///   Must return true and set  to a valid value if a 
        ///   LINQ Expression is available for this query; must return false otherwise. 
        ///   Implementations of this method must not throw exceptions.
        ///  
        /// The LINQ Expression that defines this query, if available.
        /// true if an Expression is available for this query and was successfully retrieved; otherwise false.
        internal abstract bool TryGetExpression(out System.Linq.Expressions.Expression expression);
 
        /// 
        ///   Retrieves an  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. 
        /// 
        /// The merge option which should be supported by the returned execution plan 
        /// 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  that describes the result typeof this query in terms of C-Space metadata 
        /// 
        protected abstract TypeUsage GetResultType();

        ///  
        ///   Helper method to return the first non-null merge option from the specified nullable merge options,
        ///   or the  if the value of all specified nullable merge options is null. 
        ///  
        /// The available nullable merge option values, in order of decreasing preference
        /// the first non-null merge option; or the default merge option if the value of all  is null 
        protected static MergeOption EnsureMergeOption(params MergeOption?[] preferredMergeOptions)
        {
            foreach (MergeOption? preferred in preferredMergeOptions)
            { 
                if (preferred.HasValue)
                { 
                    return preferred.Value; 
                }
            } 

            return ObjectQueryState.DefaultMergeOption;
        }
 
        /// 
        ///   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 null if the value of all  is null 
        protected static MergeOption? GetMergeOption(params MergeOption?[] preferredMergeOptions)
        {
            foreach (MergeOption? preferred in preferredMergeOptions)
            { 
                if (preferred.HasValue)
                { 
                    return preferred.Value; 
                }
            } 

            return null;
        }
 
        /// 
        /// Helper method to create a new ObjectQuery based on this query state instance. 
        ///  
        /// A new  - typed as 
        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 } ); 
        } 

        ///  
        /// 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 ObjectQuery CreateObjectQuery(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.
//---------------------------------------------------------------------- 
// 
//      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; 

    ///  
    ///   An instance of a class derived from ObjectQueryState is used to model every instance of . 
    ///   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. 
    /// 
    internal abstract class ObjectQueryState
    {
        ///  
        ///   The  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. 
        ///  
        internal static readonly MergeOption DefaultMergeOption = MergeOption.AppendOnly;
 
        /// 
        ///   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  if a guaranteed non-null collection is required.
        ///  
        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;
        } 

        /// 
        ///   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  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. 
        /// 
        internal MergeOption? UserSpecifiedMergeOption
        {
            get { return _userMergeOption; } 
            set { _userMergeOption = value; }
        } 
 
        /// 
        ///   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  and  properties on
        ///    to match the values of the corresponding properties on this instance.
        /// 
        /// 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.
        }
 
        /// 
        ///   Must return true and set  to a valid value 
        ///   if command text is available for this query; must return false otherwise. 
        ///   Implementations of this method must not throw exceptions.
        ///  
        /// The command text of this query, if available.
        /// true if command text is available for this query and was successfully retrieved; otherwise false.
        internal abstract bool TryGetCommandText(out string commandText);
 
        /// 
        ///   Must return true and set  to a valid value if a 
        ///   LINQ Expression is available for this query; must return false otherwise. 
        ///   Implementations of this method must not throw exceptions.
        ///  
        /// The LINQ Expression that defines this query, if available.
        /// true if an Expression is available for this query and was successfully retrieved; otherwise false.
        internal abstract bool TryGetExpression(out System.Linq.Expressions.Expression expression);
 
        /// 
        ///   Retrieves an  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. 
        /// 
        /// The merge option which should be supported by the returned execution plan 
        /// 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  that describes the result typeof this query in terms of C-Space metadata 
        /// 
        protected abstract TypeUsage GetResultType();

        ///  
        ///   Helper method to return the first non-null merge option from the specified nullable merge options,
        ///   or the  if the value of all specified nullable merge options is null. 
        ///  
        /// The available nullable merge option values, in order of decreasing preference
        /// the first non-null merge option; or the default merge option if the value of all  is null 
        protected static MergeOption EnsureMergeOption(params MergeOption?[] preferredMergeOptions)
        {
            foreach (MergeOption? preferred in preferredMergeOptions)
            { 
                if (preferred.HasValue)
                { 
                    return preferred.Value; 
                }
            } 

            return ObjectQueryState.DefaultMergeOption;
        }
 
        /// 
        ///   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 null if the value of all  is null 
        protected static MergeOption? GetMergeOption(params MergeOption?[] preferredMergeOptions)
        {
            foreach (MergeOption? preferred in preferredMergeOptions)
            { 
                if (preferred.HasValue)
                { 
                    return preferred.Value; 
                }
            } 

            return null;
        }
 
        /// 
        /// Helper method to create a new ObjectQuery based on this query state instance. 
        ///  
        /// A new  - typed as 
        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 } ); 
        } 

        ///  
        /// 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 ObjectQuery CreateObjectQuery(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.
                        

Link Menu

Network programming in C#, Network Programming in VB.NET, Network Programming in .NET
This book is available now!
Buy at Amazon US or
Buy at Amazon UK