mcs/class/referencesource/System.Data/System/Data/Common/DBSchemaTable.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="DBSchemaTable.cs" company="Microsoft">
   3 //      Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">Microsoft</owner>
   6 // <owner current="true" primary="false">Microsoft</owner>
   7 //------------------------------------------------------------------------------
   8
   9 namespace System.Data.Common {
  10
  11     using System;
  12     using System.Data;
  13     using System.Data.ProviderBase;
  14     using System.Diagnostics;
  15
  16     sealed internal class DbSchemaTable {
  17
  18         private enum ColumnEnum {
  19             ColumnName,
  20             ColumnOrdinal,
  21             ColumnSize,
  22             BaseServerName,
  23             BaseCatalogName,
  24             BaseColumnName,
  25             BaseSchemaName,
  26             BaseTableName,
  27             IsAutoIncrement,
  28             IsUnique,
  29             IsKey,
  30             IsRowVersion,
  31             DataType,
  32             ProviderSpecificDataType,
  33             AllowDBNull,
  34             ProviderType,
  35             IsExpression,
  36             IsHidden,
  37             IsLong,
  38             IsReadOnly,
  39             SchemaMappingUnsortedIndex,
  40         }
  41
  42         static readonly private string[] DBCOLUMN_NAME = new string[] {
  43             SchemaTableColumn.ColumnName,
  44             SchemaTableColumn.ColumnOrdinal,
  45             SchemaTableColumn.ColumnSize,
  46             SchemaTableOptionalColumn.BaseServerName,
  47             SchemaTableOptionalColumn.BaseCatalogName,
  48             SchemaTableColumn.BaseColumnName,
  49             SchemaTableColumn.BaseSchemaName,
  50             SchemaTableColumn.BaseTableName,
  51             SchemaTableOptionalColumn.IsAutoIncrement,
  52             SchemaTableColumn.IsUnique,
  53             SchemaTableColumn.IsKey,
  54             SchemaTableOptionalColumn.IsRowVersion,
  55             SchemaTableColumn.DataType,
  56             SchemaTableOptionalColumn.ProviderSpecificDataType,
  57             SchemaTableColumn.AllowDBNull,
  58             SchemaTableColumn.ProviderType,
  59             SchemaTableColumn.IsExpression,
  60             SchemaTableOptionalColumn.IsHidden,
  61             SchemaTableColumn.IsLong,
  62             SchemaTableOptionalColumn.IsReadOnly,
  63             DbSchemaRow.SchemaMappingUnsortedIndex,
  64         };
  65
  66         internal DataTable dataTable;
  67         private DataColumnCollection columns;
  68         private DataColumn[] columnCache = new DataColumn[DBCOLUMN_NAME.Length];
  69         private bool _returnProviderSpecificTypes;
  70
  71         internal DbSchemaTable(DataTable dataTable, bool returnProviderSpecificTypes) {
  72             this.dataTable = dataTable;
  73             this.columns = dataTable.Columns;
  74             _returnProviderSpecificTypes = returnProviderSpecificTypes;
  75         }
  76
  77         internal DataColumn ColumnName      { get { return CachedDataColumn(ColumnEnum.ColumnName);}}
  78         internal DataColumn Size            { get { return CachedDataColumn(ColumnEnum.ColumnSize);}}
  79         internal DataColumn BaseServerName  { get { return CachedDataColumn(ColumnEnum.BaseServerName);}}
  80         internal DataColumn BaseColumnName  { get { return CachedDataColumn(ColumnEnum.BaseColumnName);}}
  81         internal DataColumn BaseTableName   { get { return CachedDataColumn(ColumnEnum.BaseTableName);}}
  82         internal DataColumn BaseCatalogName { get { return CachedDataColumn(ColumnEnum.BaseCatalogName);}}
  83         internal DataColumn BaseSchemaName  { get { return CachedDataColumn(ColumnEnum.BaseSchemaName);}}
  84         internal DataColumn IsAutoIncrement { get { return CachedDataColumn(ColumnEnum.IsAutoIncrement);}}
  85         internal DataColumn IsUnique        { get { return CachedDataColumn(ColumnEnum.IsUnique);}}
  86         internal DataColumn IsKey           { get { return CachedDataColumn(ColumnEnum.IsKey);}}
  87         internal DataColumn IsRowVersion    { get { return CachedDataColumn(ColumnEnum.IsRowVersion);}}
  88
  89         internal DataColumn AllowDBNull              { get { return CachedDataColumn(ColumnEnum.AllowDBNull);}}
  90         internal DataColumn IsExpression             { get { return CachedDataColumn(ColumnEnum.IsExpression);}}
  91         internal DataColumn IsHidden                 { get { return CachedDataColumn(ColumnEnum.IsHidden);}}
  92         internal DataColumn IsLong                   { get { return CachedDataColumn(ColumnEnum.IsLong);}}
  93         internal DataColumn IsReadOnly               { get { return CachedDataColumn(ColumnEnum.IsReadOnly);}}
  94
  95         internal DataColumn UnsortedIndex   { get { return CachedDataColumn(ColumnEnum.SchemaMappingUnsortedIndex);}}
  96
  97         internal DataColumn DataType {
  98             get {
  99                 if (_returnProviderSpecificTypes) {
 100                     return CachedDataColumn(ColumnEnum.ProviderSpecificDataType, ColumnEnum.DataType);
 101                 }
 102                 return CachedDataColumn(ColumnEnum.DataType);
 103             }
 104         }
 105
 106         private DataColumn CachedDataColumn(ColumnEnum column) {
 107             return CachedDataColumn(column, column);
 108         }
 109
 110         private DataColumn CachedDataColumn(ColumnEnum column, ColumnEnum column2) {
 111             DataColumn dataColumn = columnCache[(int) column];
 112             if (null == dataColumn) {
 113                 int index = columns.IndexOf(DBCOLUMN_NAME[(int) column]);
 114                 if ((-1 == index) && (column != column2)) {
 115                     index = columns.IndexOf(DBCOLUMN_NAME[(int) column2]);
 116                 }
 117                 if (-1 != index) {
 118                     dataColumn = columns[index];
 119                     columnCache[(int) column] = dataColumn;
 120                 }
 121             }
 122             return dataColumn;
 123         }
 124     }
 125 }