Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

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

@@ -0,0 +1,125 @@
+//------------------------------------------------------------------------------
+// <copyright file="DBSchemaTable.cs" company="Microsoft">
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+// <owner current="true" primary="true">[....]</owner>
+// <owner current="true" primary="false">[....]</owner>
+//------------------------------------------------------------------------------
+
+namespace System.Data.Common {
+
+    using System;
+    using System.Data;
+    using System.Data.ProviderBase;
+    using System.Diagnostics;
+    
+    sealed internal class DbSchemaTable {
+
+        private enum ColumnEnum {
+            ColumnName,
+            ColumnOrdinal,
+            ColumnSize,
+            BaseServerName,
+            BaseCatalogName,
+            BaseColumnName,
+            BaseSchemaName,
+            BaseTableName,
+            IsAutoIncrement,
+            IsUnique,
+            IsKey,
+            IsRowVersion,
+            DataType,
+            ProviderSpecificDataType,
+            AllowDBNull,
+            ProviderType,
+            IsExpression,
+            IsHidden,
+            IsLong,
+            IsReadOnly,
+            SchemaMappingUnsortedIndex,
+        }
+
+        static readonly private string[] DBCOLUMN_NAME = new string[] {
+            SchemaTableColumn.ColumnName,
+            SchemaTableColumn.ColumnOrdinal,
+            SchemaTableColumn.ColumnSize,
+            SchemaTableOptionalColumn.BaseServerName,
+            SchemaTableOptionalColumn.BaseCatalogName,
+            SchemaTableColumn.BaseColumnName,
+            SchemaTableColumn.BaseSchemaName,
+            SchemaTableColumn.BaseTableName,
+            SchemaTableOptionalColumn.IsAutoIncrement,
+            SchemaTableColumn.IsUnique,
+            SchemaTableColumn.IsKey,
+            SchemaTableOptionalColumn.IsRowVersion,
+            SchemaTableColumn.DataType,
+            SchemaTableOptionalColumn.ProviderSpecificDataType,
+            SchemaTableColumn.AllowDBNull,
+            SchemaTableColumn.ProviderType,
+            SchemaTableColumn.IsExpression,
+            SchemaTableOptionalColumn.IsHidden,
+            SchemaTableColumn.IsLong,
+            SchemaTableOptionalColumn.IsReadOnly,
+            DbSchemaRow.SchemaMappingUnsortedIndex,
+        };
+
+        internal DataTable dataTable;
+        private DataColumnCollection columns;
+        private DataColumn[] columnCache = new DataColumn[DBCOLUMN_NAME.Length];
+        private bool _returnProviderSpecificTypes;
+
+        internal DbSchemaTable(DataTable dataTable, bool returnProviderSpecificTypes) {
+            this.dataTable = dataTable;
+            this.columns = dataTable.Columns;
+            _returnProviderSpecificTypes = returnProviderSpecificTypes;
+        }
+
+        internal DataColumn ColumnName      { get { return CachedDataColumn(ColumnEnum.ColumnName);}}
+        internal DataColumn Size            { get { return CachedDataColumn(ColumnEnum.ColumnSize);}}
+        internal DataColumn BaseServerName  { get { return CachedDataColumn(ColumnEnum.BaseServerName);}}
+        internal DataColumn BaseColumnName  { get { return CachedDataColumn(ColumnEnum.BaseColumnName);}}
+        internal DataColumn BaseTableName   { get { return CachedDataColumn(ColumnEnum.BaseTableName);}}
+        internal DataColumn BaseCatalogName { get { return CachedDataColumn(ColumnEnum.BaseCatalogName);}}
+        internal DataColumn BaseSchemaName  { get { return CachedDataColumn(ColumnEnum.BaseSchemaName);}}
+        internal DataColumn IsAutoIncrement { get { return CachedDataColumn(ColumnEnum.IsAutoIncrement);}}
+        internal DataColumn IsUnique        { get { return CachedDataColumn(ColumnEnum.IsUnique);}}
+        internal DataColumn IsKey           { get { return CachedDataColumn(ColumnEnum.IsKey);}}
+        internal DataColumn IsRowVersion    { get { return CachedDataColumn(ColumnEnum.IsRowVersion);}}
+
+        internal DataColumn AllowDBNull              { get { return CachedDataColumn(ColumnEnum.AllowDBNull);}}
+        internal DataColumn IsExpression             { get { return CachedDataColumn(ColumnEnum.IsExpression);}}
+        internal DataColumn IsHidden                 { get { return CachedDataColumn(ColumnEnum.IsHidden);}}
+        internal DataColumn IsLong                   { get { return CachedDataColumn(ColumnEnum.IsLong);}}
+        internal DataColumn IsReadOnly               { get { return CachedDataColumn(ColumnEnum.IsReadOnly);}}
+
+        internal DataColumn UnsortedIndex   { get { return CachedDataColumn(ColumnEnum.SchemaMappingUnsortedIndex);}}
+        
+        internal DataColumn DataType {
+            get {
+                if (_returnProviderSpecificTypes) {
+                    return CachedDataColumn(ColumnEnum.ProviderSpecificDataType, ColumnEnum.DataType);
+                }
+                return CachedDataColumn(ColumnEnum.DataType);
+            }
+        }
+
+        private DataColumn CachedDataColumn(ColumnEnum column) {
+            return CachedDataColumn(column, column);
+        }
+        
+        private DataColumn CachedDataColumn(ColumnEnum column, ColumnEnum column2) {
+            DataColumn dataColumn = columnCache[(int) column];
+            if (null == dataColumn) {
+                int index = columns.IndexOf(DBCOLUMN_NAME[(int) column]);
+                if ((-1 == index) && (column != column2)) {
+                    index = columns.IndexOf(DBCOLUMN_NAME[(int) column2]);
+                }
+                if (-1 != index) {
+                    dataColumn = columns[index];
+                    columnCache[(int) column] = dataColumn;
+                }
+            }
+            return dataColumn;
+        }
+    }
+}