Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data/System/Data/ProviderBase/DataReaderContainer.cs

@@ -0,0 +1,133 @@
+//------------------------------------------------------------------------------
+// <copyright file="DataReaderContainer.cs" company="Microsoft">
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+// <owner current="true" primary="true">[....]</owner>
+//------------------------------------------------------------------------------
+
+namespace System.Data.ProviderBase {
+
+    using System;
+    using System.Data;
+    using System.Data.Common;
+    using System.Diagnostics;
+
+    internal abstract class DataReaderContainer {
+
+        protected readonly IDataReader _dataReader;
+        protected int _fieldCount;
+
+        static internal DataReaderContainer Create(IDataReader dataReader, bool returnProviderSpecificTypes) {
+            if (returnProviderSpecificTypes) {
+                DbDataReader providerSpecificDataReader = (dataReader as DbDataReader);
+                if (null != providerSpecificDataReader) {
+                    return new ProviderSpecificDataReader(dataReader, providerSpecificDataReader);
+                }
+            }
+            return new CommonLanguageSubsetDataReader(dataReader);
+        }
+
+        protected DataReaderContainer(IDataReader dataReader) {
+            Debug.Assert(null != dataReader, "null dataReader");
+            _dataReader = dataReader;
+        }
+
+        internal int FieldCount {
+            get {
+                return _fieldCount;
+            }
+        }
+
+        internal abstract bool ReturnProviderSpecificTypes { get; }
+        protected abstract int VisibleFieldCount { get; }
+
+        internal abstract Type GetFieldType(int ordinal);
+        internal abstract object GetValue(int ordinal);
+        internal abstract int GetValues(object[] values);
+
+        internal string GetName(int ordinal) {
+            string fieldName = _dataReader.GetName(ordinal);
+            Debug.Assert(null != fieldName, "null GetName");
+            return ((null != fieldName) ? fieldName : "");
+        }
+        internal DataTable GetSchemaTable() {
+            return _dataReader.GetSchemaTable();
+        }
+        internal bool NextResult() {
+            _fieldCount = 0;
+            if (_dataReader.NextResult()) {
+                _fieldCount = VisibleFieldCount;
+                return true;
+            }
+            return false;
+        }
+        internal bool Read() {
+            return _dataReader.Read();
+        }
+
+        private sealed class ProviderSpecificDataReader : DataReaderContainer {
+            private DbDataReader _providerSpecificDataReader;
+
+            internal ProviderSpecificDataReader(IDataReader dataReader, DbDataReader dbDataReader) : base(dataReader) {
+                Debug.Assert(null != dataReader, "null dbDataReader");
+                _providerSpecificDataReader = dbDataReader;
+                _fieldCount = VisibleFieldCount;
+            }
+
+            internal override bool ReturnProviderSpecificTypes {
+                get {
+                    return true;
+                }
+            }
+            protected override int VisibleFieldCount {
+                get {
+                    int fieldCount = _providerSpecificDataReader.VisibleFieldCount;
+                    Debug.Assert(0 <= fieldCount, "negative FieldCount");
+                    return ((0 <= fieldCount) ? fieldCount : 0);
+                }
+            }
+
+            internal override Type GetFieldType(int ordinal) {
+                Type fieldType = _providerSpecificDataReader.GetProviderSpecificFieldType(ordinal);
+                Debug.Assert(null != fieldType, "null FieldType");
+                return fieldType;
+            }
+            internal override object GetValue(int ordinal) {
+                return _providerSpecificDataReader.GetProviderSpecificValue(ordinal);
+            }
+            internal override int GetValues(object[] values) {
+                return _providerSpecificDataReader.GetProviderSpecificValues(values);
+            }
+        }
+
+        private sealed class CommonLanguageSubsetDataReader : DataReaderContainer {
+
+            internal CommonLanguageSubsetDataReader(IDataReader dataReader ) : base(dataReader) {
+                _fieldCount = VisibleFieldCount;
+            }
+
+            internal override bool ReturnProviderSpecificTypes {
+                get {
+                    return false;
+                }
+            }
+            protected override int VisibleFieldCount {
+                get {
+                    int fieldCount = _dataReader.FieldCount;
+                    Debug.Assert(0 <= fieldCount, "negative FieldCount");
+                    return ((0 <= fieldCount) ? fieldCount : 0);
+                }
+            }
+
+            internal override Type GetFieldType(int ordinal) {
+                return _dataReader.GetFieldType(ordinal);
+            }
+            internal override object GetValue(int ordinal) {
+                return _dataReader.GetValue(ordinal);
+            }
+            internal override int GetValues(object[] values) {
+                return _dataReader.GetValues(values);
+            }
+        }
+    }
+}