95 lines
3.5 KiB
C#
95 lines
3.5 KiB
C#
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//---------------------------------------------------------------------
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// <copyright file="Aggregates.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.Data.Common;
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using System.Collections.Generic;
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using System.Data.Metadata.Edm;
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using System.Data.Common.CommandTrees.Internal;
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using System.Diagnostics;
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namespace System.Data.Common.CommandTrees
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{
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/// <summary>
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/// Aggregates are pseudo-expressions. They look and feel like expressions, but
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/// are severely restricted in where they can appear - only in the aggregates clause
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/// of a group-by expression.
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/// </summary>
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Db")]
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public abstract class DbAggregate
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{
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private readonly DbExpressionList _args;
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private readonly TypeUsage _type;
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internal DbAggregate(TypeUsage resultType, DbExpressionList arguments)
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{
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Debug.Assert(resultType != null, "DbAggregate.ResultType cannot be null");
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Debug.Assert(arguments != null, "DbAggregate.Arguments cannot be null");
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Debug.Assert(arguments.Count == 1, "DbAggregate requires a single argument");
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this._type = resultType;
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this._args = arguments;
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}
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/// <summary>
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/// Gets the result type of this aggregate
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/// </summary>
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public TypeUsage ResultType
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{
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get { return _type; }
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}
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/// <summary>
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/// Gets the list of expressions that define the arguments to the aggregate.
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/// </summary>
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public IList<DbExpression> Arguments { get { return _args; } }
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}
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/// <summary>
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/// The aggregate type that corresponds to exposing the collection of elements that comprise a group
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/// </summary>
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Db")]
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public sealed class DbGroupAggregate : DbAggregate
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{
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internal DbGroupAggregate(TypeUsage resultType, DbExpressionList arguments)
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: base(resultType, arguments)
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{
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}
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}
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/// <summary>
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/// The aggregate type that corresponds to the invocation of an aggregate function.
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/// </summary>
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Db")]
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public sealed class DbFunctionAggregate : DbAggregate
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{
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private bool _distinct;
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EdmFunction _aggregateFunction;
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internal DbFunctionAggregate(TypeUsage resultType, DbExpressionList arguments, EdmFunction function, bool isDistinct)
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: base(resultType, arguments)
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{
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Debug.Assert(function != null, "DbFunctionAggregate.Function cannot be null");
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_aggregateFunction = function;
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_distinct = isDistinct;
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}
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/// <summary>
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/// Gets a value indicating whether the aggregate function is applied in a distinct fashion
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/// </summary>
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public bool Distinct { get { return _distinct; } }
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/// <summary>
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/// Gets the method metadata that specifies the aggregate function to invoke.
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/// </summary>
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public EdmFunction Function { get { return _aggregateFunction; } }
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}
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}
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