mcs/class/referencesource/System.Data.Entity/System/Data/Common/Internal/Materialization/RecordStateFactory.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="recordstatefactory.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">Microsoft</owner>
   6 //------------------------------------------------------------------------------
   7
   8 using System.Collections.Generic;
   9 using System.Data.Metadata.Edm;
  10 using System.Linq;
  11 using System.Linq.Expressions;
  12
  13 namespace System.Data.Common.Internal.Materialization
  14 {
  15     /// <summary>
  16     /// An immutable class used to generate new RecordStates, which are used
  17     /// at runtime to produce value-layer (aka DataReader) results.
  18     ///
  19     /// Contains static information collected by the Translator visitor.  The
  20     /// expressions produced by the Translator are compiled.  The RecordStates
  21     /// will refer to this object for all static information.
  22     ///
  23     /// This class is cached in the query cache as part of the CoordinatorFactory.
  24     /// </summary>
  25     internal class RecordStateFactory
  26     {
  27         #region state
  28
  29         /// <summary>
  30         /// Indicates which state slot in the Shaper.State is expected to hold the
  31         /// value for this record state.  Each unique record shape has it's own state
  32         /// slot.
  33         /// </summary>
  34         internal readonly int StateSlotNumber;
  35
  36         /// <summary>
  37         /// How many column values we have to reserve space for in this record.
  38         /// </summary>
  39         internal readonly int ColumnCount;
  40
  41         /// <summary>
  42         /// The DataRecordInfo we must return for this record.  If the record represents
  43         /// an entity, this will be used to construct a unique EntityRecordInfo with the
  44         /// EntityKey and EntitySet for the entity.
  45         /// </summary>
  46         internal readonly DataRecordInfo DataRecordInfo;
  47
  48         /// <summary>
  49         /// A function that will gather the data for the row and store it on the record state.
  50         /// </summary>
  51         internal readonly Func<Shaper, bool> GatherData;
  52
  53         /// <summary>
  54         /// Collection of nested records for this record, such as a complex type that is
  55         /// part of an entity.  This does not include records that are part of a nested
  56         /// collection, however.
  57         /// </summary>
  58         internal readonly System.Collections.ObjectModel.ReadOnlyCollection<RecordStateFactory> NestedRecordStateFactories;
  59
  60         /// <summary>
  61         /// The name for each column.
  62         /// </summary>
  63         internal readonly System.Collections.ObjectModel.ReadOnlyCollection<string> ColumnNames;
  64
  65         /// <summary>
  66         /// The type usage information for each column.
  67         /// </summary>
  68         internal readonly System.Collections.ObjectModel.ReadOnlyCollection<TypeUsage> TypeUsages;
  69
  70         /// <summary>
  71         /// Tracks which columns might need special handling (nested readers/records)
  72         /// </summary>
  73         internal readonly System.Collections.ObjectModel.ReadOnlyCollection<bool> IsColumnNested;
  74
  75         /// <summary>
  76         /// Tracks whether there are ANY columns that need special handling.
  77         /// </summary>
  78         internal readonly bool HasNestedColumns;
  79
  80         /// <summary>
  81         /// A helper class to make the translation from name->ordinal.
  82         /// </summary>
  83         internal readonly FieldNameLookup FieldNameLookup;
  84
  85         /// <summary>
  86         /// Description of this RecordStateFactory, used for debugging only; while this
  87         /// is not  needed in retail code, it is pretty important because it's the only
  88         /// description we'll have once we compile the Expressions; debugging a problem
  89         /// with retail bits would be pretty hard without this.
  90         /// </summary>
  91         private readonly string Description;
  92
  93         #endregion
  94
  95         #region constructor
  96
  97         public RecordStateFactory(int stateSlotNumber, int columnCount, RecordStateFactory[] nestedRecordStateFactories, DataRecordInfo dataRecordInfo, Expression gatherData, string[] propertyNames, TypeUsage[] typeUsages)
  98         {
  99             this.StateSlotNumber = stateSlotNumber;
 100             this.ColumnCount = columnCount;
 101             this.NestedRecordStateFactories = new System.Collections.ObjectModel.ReadOnlyCollection<RecordStateFactory>(nestedRecordStateFactories);
 102             this.DataRecordInfo = dataRecordInfo;
 103             this.GatherData = Translator.Compile<bool>(gatherData);
 104             this.Description = gatherData.ToString();
 105             this.ColumnNames = new System.Collections.ObjectModel.ReadOnlyCollection<string>(propertyNames);
 106             this.TypeUsages = new System.Collections.ObjectModel.ReadOnlyCollection<TypeUsage>(typeUsages);
 107
 108             this.FieldNameLookup = new FieldNameLookup(this.ColumnNames, -1);
 109
 110             // pre-compute the nested objects from typeUsage, for performance
 111             bool[] isColumnNested = new bool[columnCount];
 112
 113             for (int ordinal = 0; ordinal < columnCount; ordinal++)
 114             {
 115                 switch (typeUsages[ordinal].EdmType.BuiltInTypeKind)
 116                 {
 117                     case BuiltInTypeKind.EntityType:
 118                     case BuiltInTypeKind.ComplexType:
 119                     case BuiltInTypeKind.RowType:
 120                     case BuiltInTypeKind.CollectionType:
 121                         isColumnNested[ordinal] = true;
 122                         this.HasNestedColumns = true;
 123                         break;
 124                     default:
 125                         isColumnNested[ordinal] = false;
 126                         break;
 127                 }
 128             }
 129             this.IsColumnNested = new System.Collections.ObjectModel.ReadOnlyCollection<bool>(isColumnNested);
 130         }
 131
 132         #endregion
 133
 134         #region "public" surface area
 135
 136         /// <summary>
 137         /// It's GO time, create the record state.
 138         /// </summary>
 139         internal RecordState Create(CoordinatorFactory coordinatorFactory)
 140         {
 141             return new RecordState(this, coordinatorFactory);
 142         }
 143
 144         #endregion
 145     }
 146
 147 }