mcs/class/referencesource/System.Data.Entity/System/Data/Mapping/ViewGeneration/Structures/ConstantProjectedSlot.cs

   1 //---------------------------------------------------------------------
   2 // <copyright file="ConstantProjectedSlot.cs" company="Microsoft">
   3 //      Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 //
   6 // @owner Microsoft
   7 // @backupOwner Microsoft
   8 //---------------------------------------------------------------------
   9
  10 using System.Data.Mapping.ViewGeneration.CqlGeneration;
  11 using System.Collections.Generic;
  12 using System.Text;
  13 using System.Diagnostics;
  14 using System.Data.Common.CommandTrees;
  15 using System.Data.Common.CommandTrees.ExpressionBuilder;
  16
  17 namespace System.Data.Mapping.ViewGeneration.Structures
  18 {
  19     /// <summary>
  20     /// A constant that can be projected in a cell query.
  21     /// </summary>
  22     internal sealed class ConstantProjectedSlot : ProjectedSlot
  23     {
  24         #region Constructors
  25         /// <summary>
  26         /// Creates a slot with constant value being <paramref name="value"/>.
  27         /// </summary>
  28         internal ConstantProjectedSlot(Constant value, MemberPath memberPath)
  29         {
  30             Debug.Assert(value != null);
  31             Debug.Assert(value.IsNotNull() == false, "Cannot store NotNull in a slot - NotNull is only for conditions");
  32             m_constant = value;
  33             m_memberPath = memberPath;
  34         }
  35         #endregion
  36
  37         #region Fields
  38         /// <summary>
  39         /// The actual value.
  40         /// </summary>
  41         private readonly Constant m_constant;
  42         private readonly MemberPath m_memberPath;
  43         #endregion
  44
  45         #region Properties
  46         /// <summary>
  47         /// Returns the value stored in this constant.
  48         /// </summary>
  49         internal Constant CellConstant
  50         {
  51             get { return m_constant; }
  52         }
  53
  54         #endregion
  55
  56         #region Methods
  57         internal override ProjectedSlot DeepQualify(CqlBlock block)
  58         {
  59             return this; // Nothing to create
  60         }
  61
  62         internal override StringBuilder AsEsql(StringBuilder builder, MemberPath outputMember, string blockAlias, int indentLevel)
  63         {
  64             return m_constant.AsEsql(builder, outputMember, blockAlias);
  65         }
  66
  67         internal override DbExpression AsCqt(DbExpression row, MemberPath outputMember)
  68         {
  69             return m_constant.AsCqt(row, outputMember);
  70         }
  71
  72         protected override bool IsEqualTo(ProjectedSlot right)
  73         {
  74             ConstantProjectedSlot rightSlot = right as ConstantProjectedSlot;
  75             if (rightSlot == null)
  76             {
  77                 return false;
  78             }
  79             return Constant.EqualityComparer.Equals(m_constant, rightSlot.m_constant);
  80         }
  81
  82         protected override int GetHash()
  83         {
  84             return Constant.EqualityComparer.GetHashCode(m_constant);
  85         }
  86
  87         internal override void ToCompactString(StringBuilder builder)
  88         {
  89             m_constant.ToCompactString(builder);
  90         }
  91         #endregion
  92     }
  93 }