dbenumerator.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / Common / dbenumerator.cs / 2 / dbenumerator.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
//----------------------------------------------------------------------------- 
 
namespace System.Data.Common {
 
    using System;
    using System.Collections;
    using System.Data;
    using System.Data.ProviderBase; 
    using System.Diagnostics;
    using System.ComponentModel; 
 
#if WINFSInternalOnly
    internal 
#else
    public
#endif
    class DbEnumerator : IEnumerator { 

        internal IDataReader _reader; 
        internal IDataRecord _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 object Current {
            get { 
                return _current;
            } 
        } 

        /*public IDataRecord Current { 
            get {
                return _current;
            }
        }*/ 

/* 
        virtual internal IDataRecord NewRecord(SchemaInfo[] si, object[] values, PropertyDescriptorCollection descriptors) { 
            return new DbDataRecord(si, values, descriptors);
        } 

        virtual internal void GetValues(object[] values) {
            _reader.GetValues(values);
        } 
*/
 
        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; 
            }
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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