TemplateKey.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / TemplateKey.cs / 1305600 / TemplateKey.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// Description: Base class for DataTemplateKey, TableTemplateKey. 
// 
//---------------------------------------------------------------------------
 
using System;
using System.Reflection;
using System.ComponentModel;
using System.Windows.Markup; 
using MS.Internal.Data;         // DataBindEngine.EnglishUSCulture
 
namespace System.Windows 
{
    ///  The TemplateKey object is used as the resource key for data templates 
    [TypeConverter(typeof(TemplateKeyConverter))]
    public abstract class TemplateKey : ResourceKey, ISupportInitialize
    {
        ///  Constructor (called by derived classes only)  
        protected TemplateKey(TemplateType templateType)
        { 
            _dataType = null;   // still needs to be initialized 
            _templateType = templateType;
        } 

        ///  Constructor (called by derived classes only) 
        protected TemplateKey(TemplateType templateType, object dataType)
        { 
            Exception ex = ValidateDataType(dataType, "dataType");
            if (ex != null) 
                throw ex; 

            _dataType = dataType; 
            _templateType = templateType;
        }

#region ISupportInitialize 

        /// Begin Initialization 
        void ISupportInitialize.BeginInit() 
        {
            _initializing = true; 
        }

        /// End Initialization, verify that internal state is consistent
        void ISupportInitialize.EndInit() 
        {
            if (_dataType == null) 
            { 
                throw new InvalidOperationException(SR.Get(SRID.PropertyMustHaveValue, "DataType", this.GetType().Name));
            } 

            _initializing = false;
        }
 
#endregion ISupportInitialize
 
        ///  
        /// The type for which the template is designed.  This is either
        /// a Type (for object data), or a string (for XML data).  In the latter 
        /// case the string denotes the XML tag name.
        /// 
        public object DataType
        { 
            get { return _dataType; }
            set 
            { 
                if (!_initializing)
                    throw new InvalidOperationException(SR.Get(SRID.PropertyIsInitializeOnly, "DataType", this.GetType().Name)); 
                if (_dataType != null && value != _dataType)
                    throw new InvalidOperationException(SR.Get(SRID.PropertyIsImmutable, "DataType", this.GetType().Name));

                Exception ex = ValidateDataType(value, "value"); 
                if (ex != null)
                    throw ex; 
 
                _dataType = value;
            } 
        }

        ///  Override of Object.GetHashCode() 
        public override int GetHashCode() 
        {
            // note that the hash code can change, but only during intialization 
            // and only once (DataType can only be changed once, from null to 
            // non-null, and that can only happen during [Begin/End]Init).
            // Technically this is still a violation of the "constant during 
            // lifetime" rule, however in practice this is acceptable.  It is
            // very unlikely that someone will put a TemplateKey into a hashtable
            // before it is initialized.
 
            int hashcode = (int)_templateType;
 
            if (_dataType != null) 
            {
                hashcode += _dataType.GetHashCode(); 
            }

            return hashcode;
        } 

        ///  Override of Object.Equals()  
        public override bool Equals(object o) 
        {
            TemplateKey key = o as TemplateKey; 
            if (key != null)
            {
                return  _templateType == key._templateType &&
                        Object.Equals(_dataType, key._dataType); 
            }
            return false; 
        } 

        ///  Override of Object.ToString()  
        public override string ToString()
        {
            Type type = DataType as Type;
            return (DataType != null) 
                    ?   String.Format(TypeConverterHelper.InvariantEnglishUS, "{0}({1})",
                                    this.GetType().Name, DataType) 
                    :   String.Format(TypeConverterHelper.InvariantEnglishUS, "{0}(null)", 
                                    this.GetType().Name);
        } 

        /// 
        ///     Allows SystemResources to know which assembly the template might be defined in.
        ///  
        public override Assembly Assembly
        { 
            get 
            {
                Type type = _dataType as Type; 
                if (type != null)
                {
                    return type.Assembly;
                } 

                return null; 
            } 
        }
 
        ///  The different types of templates that use TemplateKey 
        protected enum TemplateType
        {
            ///  DataTemplate  
            DataTemplate,
            ///  TableTemplate  
            TableTemplate, 
        }
 
        // Validate against these rules
        //  1. dataType must not be null (except at initialization, which is tested at EndInit)
        //  2. dataType must be either a Type (object data) or a string (XML tag name)
        //  3. dataType cannot be typeof(Object) 
        internal static Exception ValidateDataType(object dataType, string argName)
        { 
            Exception result = null; 

            if (dataType == null) 
            {
                result = new ArgumentNullException(argName);
            }
            else if (!(dataType is Type) && !(dataType is String)) 
            {
                result = new ArgumentException(SR.Get(SRID.MustBeTypeOrString, dataType.GetType().Name), argName); 
            } 
            else if (typeof(Object).Equals(dataType))
            { 
                result = new ArgumentException(SR.Get(SRID.DataTypeCannotBeObject), argName);
            }

            return result; 
        }
 
        object _dataType; 
        TemplateType _templateType;
        bool _initializing; 
    }
}


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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TemplateKey.cs source code in C# .NET

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