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//---------------------------------------------------------------------
// <copyright file="SpanIndex.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupowner Microsoft
//---------------------------------------------------------------------
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
{
/// <summary>
/// An index containing information about how the query was spanned
/// This helps to determine how to materialize the query result
/// </summary>
internal sealed class SpanIndex
{
#region Nested types
/// <summary>
/// Helper class to compare two RowTypes using EdmEquals instead of reference equality.
/// </summary>
sealed private class RowTypeEqualityComparer : IEqualityComparer<RowType>
{
private RowTypeEqualityComparer() { }
internal static readonly RowTypeEqualityComparer Instance = new RowTypeEqualityComparer();
#region IEqualityComparer<RowType> 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<RowType, Dictionary<int, AssociationEndMember>> _spanMap;
// A map from a spanned RowType (or parent RowType) to the original TypeUsage prior
// to the query being rewritten
private Dictionary<RowType, TypeUsage> _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<RowType, TypeUsage>(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<int, AssociationEndMember> 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<RowType, Dictionary<int, AssociationEndMember>>(RowTypeEqualityComparer.Instance);
}
_spanMap[rowType] = columnMap;
}
internal Dictionary<int, AssociationEndMember> GetSpanMap(RowType rowType)
{
Dictionary<int, AssociationEndMember> retMap = null;
if (_spanMap != null && _spanMap.TryGetValue(rowType, out retMap))
{
return retMap;
}
return null;
}
}
}
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