CompositeKey.cs source code in C# .NET

                        Code:
                         / Dotnetfx_Vista_SP2 / Dotnetfx_Vista_SP2 / 8.0.50727.4016 / DEVDIV / depot / DevDiv / releases / Orcas / QFE / ndp / fx / src / DataEntity / System / Data / Map / Update / Internal / CompositeKey.cs / 2 / CompositeKey.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using KeyComponent = System.Collections.Generic.KeyValuePair; 
using System.Data.Common.Utils;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics; 
namespace System.Data.Mapping.Update.Internal
{ 
    ///  
    /// Represents a key composed of multiple parts.
    ///  
    internal class CompositeKey
    {
        #region Fields
        ///  
        /// Gets components of this composite key.
        ///  
        internal readonly KeyComponent[] KeyComponents; 
        #endregion
 
        #region Constructors
        /// 
        /// Initialize a new composite key using the given constant values. Order is important.
        ///  
        /// Constants composing key
        internal CompositeKey(PropagatorResult[] constants) 
        { 
            Debug.Assert(null != constants, "key values must be given");
 
            KeyComponents = new KeyComponent[constants.Length];

            for (int i = 0; i < constants.Length; i++)
            { 
                PropagatorResult constant = constants[i];
                Debug.Assert(null != constant, "all key values must be set"); 
 
                Int64 identifier = constant.Identifier;
                KeyComponents[i] = new KeyComponent(constant, identifier); 
            }
        }
        #endregion
 
        #region Methods
        ///  
        /// Creates a key comparer operating in the context of the given translator. 
        /// 
        internal static IEqualityComparer CreateComparer(KeyManager keyManager) 
        {
            return new CompositeKeyComparer(keyManager);
        }
        #endregion 

        ///  
        /// Equality and comparison implementation for composite keys. 
        /// 
        private class CompositeKeyComparer : IEqualityComparer 
        {
            private readonly KeyManager _manager;

            internal CompositeKeyComparer(KeyManager manager) 
            {
                _manager = EntityUtil.CheckArgumentNull(manager, "manager"); 
            } 

            // determines equality by comparing each key component 
            public bool Equals(CompositeKey left, CompositeKey right)
            {
                // Short circuit the comparison if we know the other reference is equivalent
                if (object.ReferenceEquals(left, right)) { return true; } 

                // If either side is null, return false order (both can't be null because of 
                // the previous check) 
                if (null == left || null == right) { return false; }
 
                Debug.Assert(null != left.KeyComponents && null != right.KeyComponents,
                    "(Update/JoinPropagator) CompositeKey must be initialized");

                if (left.KeyComponents.Length != right.KeyComponents.Length) { return false; } 

                for (int i = 0; i < left.KeyComponents.Length; i++) 
                { 
                    object leftValue = GetValue(left.KeyComponents[i]);
                    object rightValue = GetValue(right.KeyComponents[i]); 

                    if (!CdpEqualityComparer.DefaultEqualityComparer.Equals(leftValue, rightValue))
                    {
                        return false; 
                    }
                } 
 
                return true;
            } 

            // creates a hash code by XORing hash codes for all key components.
            public int GetHashCode(CompositeKey key)
            { 
                EntityUtil.CheckArgumentNull(key, "key");
 
                int result = 0; 
                foreach (KeyComponent keyComponent in key.KeyComponents)
                { 
                    result ^= GetValue(keyComponent).GetHashCode();
                }

                return result; 
            }
 
            // Gets the value to use for equality checks given a key component 
            private object GetValue(KeyComponent keyComponent)
            { 
                if (keyComponent.Value == PropagatorResult.NullIdentifier)
                {
                    // no identifier exists for this key component, so use the actual key
                    // value 
                    Debug.Assert(null != keyComponent.Key && null != keyComponent.Key,
                        "key value must not be null"); 
                    return keyComponent.Key.GetSimpleValue(); 
                }
                else 
                {
                    // use the identifier rather than the actual value (since uniqueness
                    // is not guaranteed for client generated key values in the object layer)
                    return _manager.GetCanonicalIdentifier(keyComponent.Value); 
                }
            } 
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using KeyComponent = System.Collections.Generic.KeyValuePair; 
using System.Data.Common.Utils;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics; 
namespace System.Data.Mapping.Update.Internal
{ 
    ///  
    /// Represents a key composed of multiple parts.
    ///  
    internal class CompositeKey
    {
        #region Fields
        ///  
        /// Gets components of this composite key.
        ///  
        internal readonly KeyComponent[] KeyComponents; 
        #endregion
 
        #region Constructors
        /// 
        /// Initialize a new composite key using the given constant values. Order is important.
        ///  
        /// Constants composing key
        internal CompositeKey(PropagatorResult[] constants) 
        { 
            Debug.Assert(null != constants, "key values must be given");
 
            KeyComponents = new KeyComponent[constants.Length];

            for (int i = 0; i < constants.Length; i++)
            { 
                PropagatorResult constant = constants[i];
                Debug.Assert(null != constant, "all key values must be set"); 
 
                Int64 identifier = constant.Identifier;
                KeyComponents[i] = new KeyComponent(constant, identifier); 
            }
        }
        #endregion
 
        #region Methods
        ///  
        /// Creates a key comparer operating in the context of the given translator. 
        /// 
        internal static IEqualityComparer CreateComparer(KeyManager keyManager) 
        {
            return new CompositeKeyComparer(keyManager);
        }
        #endregion 

        ///  
        /// Equality and comparison implementation for composite keys. 
        /// 
        private class CompositeKeyComparer : IEqualityComparer 
        {
            private readonly KeyManager _manager;

            internal CompositeKeyComparer(KeyManager manager) 
            {
                _manager = EntityUtil.CheckArgumentNull(manager, "manager"); 
            } 

            // determines equality by comparing each key component 
            public bool Equals(CompositeKey left, CompositeKey right)
            {
                // Short circuit the comparison if we know the other reference is equivalent
                if (object.ReferenceEquals(left, right)) { return true; } 

                // If either side is null, return false order (both can't be null because of 
                // the previous check) 
                if (null == left || null == right) { return false; }
 
                Debug.Assert(null != left.KeyComponents && null != right.KeyComponents,
                    "(Update/JoinPropagator) CompositeKey must be initialized");

                if (left.KeyComponents.Length != right.KeyComponents.Length) { return false; } 

                for (int i = 0; i < left.KeyComponents.Length; i++) 
                { 
                    object leftValue = GetValue(left.KeyComponents[i]);
                    object rightValue = GetValue(right.KeyComponents[i]); 

                    if (!CdpEqualityComparer.DefaultEqualityComparer.Equals(leftValue, rightValue))
                    {
                        return false; 
                    }
                } 
 
                return true;
            } 

            // creates a hash code by XORing hash codes for all key components.
            public int GetHashCode(CompositeKey key)
            { 
                EntityUtil.CheckArgumentNull(key, "key");
 
                int result = 0; 
                foreach (KeyComponent keyComponent in key.KeyComponents)
                { 
                    result ^= GetValue(keyComponent).GetHashCode();
                }

                return result; 
            }
 
            // Gets the value to use for equality checks given a key component 
            private object GetValue(KeyComponent keyComponent)
            { 
                if (keyComponent.Value == PropagatorResult.NullIdentifier)
                {
                    // no identifier exists for this key component, so use the actual key
                    // value 
                    Debug.Assert(null != keyComponent.Key && null != keyComponent.Key,
                        "key value must not be null"); 
                    return keyComponent.Key.GetSimpleValue(); 
                }
                else 
                {
                    // use the identifier rather than the actual value (since uniqueness
                    // is not guaranteed for client generated key values in the object layer)
                    return _manager.GetCanonicalIdentifier(keyComponent.Value); 
                }
            } 
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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CompositeKey.cs source code in C# .NET

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