Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

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

@@ -0,0 +1,157 @@
+//------------------------------------------------------------------------------
+// <copyright file="dbenumerator.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.Collections;
+    using System.Data;
+    using System.Data.ProviderBase;
+    using System.Diagnostics;
+    using System.ComponentModel;
+
+    public class DbEnumerator : IEnumerator {
+
+        internal IDataReader _reader;
+        internal DbDataRecord _current;
+        internal SchemaInfo[] _schemaInfo; // shared schema info among all the data records
+        internal PropertyDescriptorCollection _descriptors; // cached property descriptors
+        private FieldNameLookup _fieldNameLookup; // MDAC 69015
+        private bool closeReader;
+
+        // users must get enumerators off of the datareader interfaces
+        public DbEnumerator(IDataReader reader) {
+            if (null == reader) {
+                throw ADP.ArgumentNull("reader");
+            }
+            _reader = reader;
+        }
+
+        public DbEnumerator(IDataReader reader, bool closeReader) { // MDAC 68670
+            if (null == reader) {
+                throw ADP.ArgumentNull("reader");
+            }
+            _reader = reader;
+            this.closeReader = closeReader;
+        }
+        
+        public DbEnumerator(DbDataReader reader)
+            : this((IDataReader)reader) {
+        }
+
+        public DbEnumerator(DbDataReader reader, bool closeReader) 
+            : this((IDataReader)reader, closeReader) {
+        }
+
+        public object Current {
+            get {
+                return _current;
+            }
+        }
+        
+        public bool MoveNext() {
+
+            if (null == _schemaInfo) {
+                  BuildSchemaInfo();
+            }
+
+            Debug.Assert(null != _schemaInfo && null != _descriptors, "unable to build schema information!");
+            _current = null;
+
+            if (_reader.Read()) {
+                // setup our current record
+                object[] values = new object[_schemaInfo.Length];
+                _reader.GetValues(values); // this.GetValues()
+                _current = new DataRecordInternal(_schemaInfo, values, _descriptors, _fieldNameLookup); // this.NewRecord()
+                return true;
+            }
+            if (closeReader) {
+                _reader.Close();
+            }
+            return false;
+        }
+
+        [ EditorBrowsableAttribute(EditorBrowsableState.Never) ] // MDAC 69508
+        public void Reset() {
+            throw ADP.NotSupported();
+        }
+
+        private void BuildSchemaInfo() {
+            int count = _reader.FieldCount;
+            string[] fieldnames = new string[count];
+            for (int i = 0; i < count; ++i) {
+                fieldnames[i] = _reader.GetName(i);
+            }
+            ADP.BuildSchemaTableInfoTableNames(fieldnames); // MDAC 71401
+
+            SchemaInfo[] si = new SchemaInfo[count];
+            PropertyDescriptor[] props = new PropertyDescriptor[_reader.FieldCount];
+            for (int i = 0; i < si.Length; i++) {
+                SchemaInfo s = new SchemaInfo();
+                s.name = _reader.GetName(i);
+                s.type = _reader.GetFieldType(i);
+                s.typeName = _reader.GetDataTypeName(i);
+                props[i] = new DbColumnDescriptor(i, fieldnames[i], s.type);
+                si[i] = s;
+            }
+
+            _schemaInfo = si;
+            _fieldNameLookup = new FieldNameLookup(_reader, -1); // MDAC 71470
+            _descriptors = new PropertyDescriptorCollection(props);
+        }
+
+        sealed private class DbColumnDescriptor : PropertyDescriptor {
+            int _ordinal;
+            Type _type;
+
+            internal DbColumnDescriptor(int ordinal, string name, Type type)
+                : base(name, null) {
+                _ordinal = ordinal;
+                _type = type;
+            }
+
+            public override Type ComponentType {
+                get {
+                    return typeof(IDataRecord);
+                }
+            }
+
+            public override bool IsReadOnly {
+                get {
+                    return true;
+                }
+            }
+
+            public override Type PropertyType {
+                get {
+                    return _type;
+                }
+            }
+
+            public override bool CanResetValue(object component) {
+                return false;
+            }
+
+            public override object GetValue(object component) {
+                return ((IDataRecord)component)[_ordinal];
+            }
+
+            public override void ResetValue(object component) {
+                throw ADP.NotSupported();
+            }
+
+            public override void SetValue(object component, object value) {
+                throw ADP.NotSupported();
+            }
+
+            public override bool ShouldSerializeValue(object component) {
+                return false;
+            }
+        }
+    }
+}