mcs/class/referencesource/System.Data.Entity/System/Data/Mapping/ViewGeneration/CqlGeneration/AliasedSlot.cs

   1 //---------------------------------------------------------------------
   2 // <copyright file="AliasedSlot.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.Linq;
  11 using System.Data.Mapping.ViewGeneration.Structures;
  12 using System.Text;
  13 using System.Diagnostics;
  14 using System.Data.Common.CommandTrees;
  15 using System.Data.Common.CommandTrees.ExpressionBuilder;
  16 using System.Data.Common.Utils;
  17 using System.Collections.Generic;
  18
  19 namespace System.Data.Mapping.ViewGeneration.CqlGeneration
  20 {
  21     /// <summary>
  22     /// Encapsulates a slot in a particular cql block.
  23     /// </summary>
  24     internal sealed class QualifiedSlot : ProjectedSlot
  25     {
  26         #region Constructor
  27         /// <summary>
  28         /// Creates a qualified slot "block_alias.slot_alias"
  29         /// </summary>
  30         internal QualifiedSlot(CqlBlock block, ProjectedSlot slot)
  31         {
  32             Debug.Assert(block != null && slot != null, "Null input to QualifiedSlot constructor");
  33             m_block = block;
  34             m_slot = slot; // Note: slot can be another qualified slot.
  35         }
  36         #endregion
  37
  38         #region Fields
  39         private readonly CqlBlock m_block;
  40         private readonly ProjectedSlot m_slot;
  41         #endregion
  42
  43         #region Methods
  44         /// <summary>
  45         /// Creates new <see cref="ProjectedSlot"/> that is qualified with <paramref name="block"/>.CqlAlias.
  46         /// If current slot is composite (such as <see cref="CaseStatementProjectedSlot"/>, then this method recursively qualifies all parts
  47         /// and returns a new deeply qualified slot (as opposed to <see cref="CqlBlock.QualifySlotWithBlockAlias"/>).
  48         /// </summary>
  49         internal override ProjectedSlot DeepQualify(CqlBlock block)
  50         {
  51             // We take the slot inside this and change the block
  52             QualifiedSlot result = new QualifiedSlot(block, m_slot);
  53             return result;
  54         }
  55
  56         /// <summary>
  57         /// Delegates alias generation to the leaf slot in the qualified chain.
  58         /// </summary>
  59         internal override string GetCqlFieldAlias(MemberPath outputMember)
  60         {
  61             // Keep looking inside the chain of qualified slots till we find a non-qualified slot and then get the alias name for it.
  62             string result = GetOriginalSlot().GetCqlFieldAlias(outputMember);
  63             return result;
  64         }
  65
  66         /// <summary>
  67         /// Walks the chain of <see cref="QualifiedSlot"/>s starting from the current one and returns the original slot.
  68         /// </summary>
  69         internal ProjectedSlot GetOriginalSlot()
  70         {
  71             ProjectedSlot slot = m_slot;
  72             while (true)
  73             {
  74                 QualifiedSlot qualifiedSlot = slot as QualifiedSlot;
  75                 if (qualifiedSlot == null)
  76                 {
  77                     break;
  78                 }
  79                 slot = qualifiedSlot.m_slot;
  80             }
  81             return slot;
  82         }
  83
  84         internal string GetQualifiedCqlName(MemberPath outputMember)
  85         {
  86             return CqlWriter.GetQualifiedName(m_block.CqlAlias, GetCqlFieldAlias(outputMember));
  87         }
  88
  89         internal override StringBuilder AsEsql(StringBuilder builder, MemberPath outputMember, string blockAlias, int indentLevel)
  90         {
  91             Debug.Assert(blockAlias == null || m_block.CqlAlias == blockAlias, "QualifiedSlot: blockAlias mismatch");
  92             builder.Append(GetQualifiedCqlName(outputMember));
  93             return builder;
  94         }
  95
  96         internal override DbExpression AsCqt(DbExpression row, MemberPath outputMember)
  97         {
  98             return m_block.GetInput(row).Property(GetCqlFieldAlias(outputMember));
  99         }
 100
 101         internal override void ToCompactString(StringBuilder builder)
 102         {
 103             StringUtil.FormatStringBuilder(builder, "{0} ", m_block.CqlAlias);
 104             m_slot.ToCompactString(builder);
 105         }
 106         #endregion
 107     }
 108 }