130 lines
4.2 KiB
C#
130 lines
4.2 KiB
C#
//---------------------------------------------------------------------
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// <copyright file="SpanIndex.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//
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// @owner [....]
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// @backupowner [....]
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//---------------------------------------------------------------------
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Data.Common;
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using System.Data.Common.Utils;
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using System.Data.Metadata.Edm;
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using System.Data.Common.CommandTrees;
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namespace System.Data.Objects.Internal
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{
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/// <summary>
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/// An index containing information about how the query was spanned
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/// This helps to determine how to materialize the query result
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/// </summary>
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internal sealed class SpanIndex
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{
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#region Nested types
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/// <summary>
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/// Helper class to compare two RowTypes using EdmEquals instead of reference equality.
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/// </summary>
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sealed private class RowTypeEqualityComparer : IEqualityComparer<RowType>
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{
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private RowTypeEqualityComparer() { }
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internal static readonly RowTypeEqualityComparer Instance = new RowTypeEqualityComparer();
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#region IEqualityComparer<RowType> Members
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public bool Equals(RowType x, RowType y)
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{
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if (x == null || y == null)
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{
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return false;
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}
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return x.EdmEquals(y);
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}
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public int GetHashCode(RowType obj)
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{
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return obj.Identity.GetHashCode();
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}
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#endregion
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}
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#endregion
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// When a query is spanned, the result is always a RowType
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// The _spanMap index maps RowTypes that are a span result to a map between
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// column ordinal and end member metadata of the type that is spanned
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private Dictionary<RowType, Dictionary<int, AssociationEndMember>> _spanMap;
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// A map from a spanned RowType (or parent RowType) to the original TypeUsage prior
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// to the query being rewritten
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private Dictionary<RowType, TypeUsage> _rowMap;
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internal SpanIndex()
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{
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}
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internal void AddSpannedRowType(RowType spannedRowType, TypeUsage originalRowType)
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{
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Debug.Assert(spannedRowType != null, "Spanned RowType cannot be null");
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Debug.Assert(originalRowType != null, "Original RowType cannot be null");
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Debug.Assert(originalRowType.EdmType.BuiltInTypeKind == BuiltInTypeKind.RowType, "Original RowType must be a RowType");
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if (null == _rowMap)
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{
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_rowMap = new Dictionary<RowType, TypeUsage>(RowTypeEqualityComparer.Instance);
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}
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_rowMap[spannedRowType] = originalRowType;
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}
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internal TypeUsage GetSpannedRowType(RowType spannedRowType)
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{
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TypeUsage retType;
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if (_rowMap != null && _rowMap.TryGetValue(spannedRowType, out retType))
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{
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return retType;
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}
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return null;
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}
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internal bool HasSpanMap(RowType spanRowType)
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{
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Debug.Assert(spanRowType != null, "Span RowType cannot be null");
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if (null == _spanMap)
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{
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return false;
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}
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return _spanMap.ContainsKey(spanRowType);
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}
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internal void AddSpanMap(RowType rowType, Dictionary<int, AssociationEndMember> columnMap)
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{
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Debug.Assert(rowType != null, "Span row type cannot be null");
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Debug.Assert(columnMap != null, "Span column map cannot be null");
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if (null == _spanMap)
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{
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_spanMap = new Dictionary<RowType, Dictionary<int, AssociationEndMember>>(RowTypeEqualityComparer.Instance);
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}
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_spanMap[rowType] = columnMap;
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}
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internal Dictionary<int, AssociationEndMember> GetSpanMap(RowType rowType)
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{
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Dictionary<int, AssociationEndMember> retMap = null;
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if (_spanMap != null && _spanMap.TryGetValue(rowType, out retMap))
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{
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return retMap;
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}
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return null;
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}
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}
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}
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