SpanIndex.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Objects / SpanIndex.cs / 1305376 / SpanIndex.cs
                        

                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner [....]
// @backupowner [....] 
//--------------------------------------------------------------------- 

using System; 
using System.Collections.Generic;
using System.Diagnostics;
using System.Data.Common;
using System.Data.Common.Utils; 
using System.Data.Metadata.Edm;
using System.Data.Common.CommandTrees; 
 
namespace System.Data.Objects.Internal
{ 
    /// 
    /// An index containing information about how the query was spanned
    /// This helps to determine how to materialize the query result
    ///  
    internal sealed class SpanIndex
    { 
        #region Nested types 

        ///  
        /// Helper class to compare two RowTypes using EdmEquals instead of reference equality.
        /// 
        sealed private class RowTypeEqualityComparer : IEqualityComparer
        { 
            private RowTypeEqualityComparer() { }
            internal static readonly RowTypeEqualityComparer Instance = new RowTypeEqualityComparer(); 
 
            #region IEqualityComparer Members
 
            public bool Equals(RowType x, RowType y)
            {
                if (x == null || y == null)
                { 
                    return false;
                } 
 
                return x.EdmEquals(y);
            } 

            public int GetHashCode(RowType obj)
            {
                return obj.Identity.GetHashCode(); 
            }
 
            #endregion 
        }
        #endregion 

        // When a query is spanned, the result is always a RowType
        // The _spanMap index maps RowTypes that are a span result to a map between
        // column ordinal and end member metadata of the type that is spanned 
        private Dictionary> _spanMap;
 
        // A map from a spanned RowType (or parent RowType) to the original TypeUsage prior 
        // to the query being rewritten
        private Dictionary _rowMap; 

        internal SpanIndex()
        {
        } 

        internal void AddSpannedRowType(RowType spannedRowType, TypeUsage originalRowType) 
        { 
            Debug.Assert(spannedRowType != null, "Spanned RowType cannot be null");
            Debug.Assert(originalRowType != null, "Original RowType cannot be null"); 
            Debug.Assert(originalRowType.EdmType.BuiltInTypeKind == BuiltInTypeKind.RowType, "Original RowType must be a RowType");

            if (null == _rowMap)
            { 
                _rowMap = new Dictionary(RowTypeEqualityComparer.Instance);
            } 
 
            _rowMap[spannedRowType] = originalRowType;
        } 

        internal TypeUsage GetSpannedRowType(RowType spannedRowType)
        {
            TypeUsage retType; 
            if (_rowMap != null && _rowMap.TryGetValue(spannedRowType, out retType))
            { 
                return retType; 
            }
            return null; 
        }

        internal bool HasSpanMap(RowType spanRowType)
        { 
            Debug.Assert(spanRowType != null, "Span RowType cannot be null");
            if (null == _spanMap) 
            { 
                return false;
            } 

            return _spanMap.ContainsKey(spanRowType);
        }
 
        internal void AddSpanMap(RowType rowType, Dictionary columnMap)
        { 
            Debug.Assert(rowType != null, "Span row type cannot be null"); 
            Debug.Assert(columnMap != null, "Span column map cannot be null");
 
            if (null == _spanMap)
            {
                _spanMap = new Dictionary>(RowTypeEqualityComparer.Instance);
            } 

            _spanMap[rowType] = columnMap; 
        } 

        internal Dictionary GetSpanMap(RowType rowType) 
        {
            Dictionary retMap = null;
            if (_spanMap != null && _spanMap.TryGetValue(rowType, out retMap))
            { 
                return retMap;
            } 
 
            return null;
        } 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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