FileLogRecordEnumerator.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / WCF / Log / System / IO / Log / FileLogRecordEnumerator.cs / 1305376 / FileLogRecordEnumerator.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------
namespace System.IO.Log
{ 
    using System;
    using System.Collections; 
    using System.Collections.Generic; 

    internal class FileLogRecordEnumerable : IEnumerable 
    {
        LogRecordEnumeratorType logRecordEnum;
        SimpleFileLog log;
        SequenceNumber start; 
        bool enumRestartAreas;
 
        internal FileLogRecordEnumerable( 
            SimpleFileLog log,
            SequenceNumber start, 
            LogRecordEnumeratorType logRecordEnum,
            bool enumRestartAreas)
        {
            this.log = log; 
            this.start = start;
            this.logRecordEnum = logRecordEnum; 
            this.enumRestartAreas = enumRestartAreas; 
        }
 
        IEnumerator IEnumerable.GetEnumerator()
        {
            return this.GetEnumerator();
        } 

        public IEnumerator GetEnumerator() 
        { 
            return new FileLogRecordEnumerator(
                                        log, 
                                        start,
                                        logRecordEnum,
                                        enumRestartAreas);
        } 
    }
 
    internal class FileLogRecordEnumerator : IEnumerator 
    {
        FileLogRecordStream stream = null; 
        FileLogRecord record = null;
        bool enumStarted = false;
        SequenceNumber start;
        SequenceNumber current; 
        LogRecordEnumeratorType logRecordEnum;
        SimpleFileLog log; 
        bool disposed = false; 
        bool enumRestartAreas;
 
        internal FileLogRecordEnumerator(
            SimpleFileLog log,
            SequenceNumber start,
            LogRecordEnumeratorType logRecordEnum, 
            bool enumRestartAreas)
        { 
            this.log = log; 
            this.start = start;
            this.current = start; 
            this.logRecordEnum = logRecordEnum;
            this.enumRestartAreas = enumRestartAreas;
        }
 
        object IEnumerator.Current
        { 
            get 
            {
                return this.Current; 
            }
        }

        public LogRecord Current 
        {
            get 
            { 
                if (this.disposed)
#pragma warning suppress 56503 
                     throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());

// IEnumerable interface contract for "current" member can throw InvalidOperationException. Suppressing this warning.
 
                if (!this.enumStarted)
#pragma warning suppress 56503 
                   throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.EnumNotStarted()); 

                if (this.record == null) 
#pragma warning suppress 56503
                     throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.EnumEnded());

                return this.record; 
            }
        } 
 

        public bool MoveNext() 
        {
            if (this.disposed)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());
 
            if (this.current == SequenceNumber.Invalid)
                return false; 
 
            if (!this.enumStarted)
            { 
                this.enumStarted = true;
            }
            else
            { 
                switch (this.logRecordEnum)
                { 
                    case LogRecordEnumeratorType.Next: 
                        this.current = this.stream.NextLsn;
                        break; 
                    case LogRecordEnumeratorType.Previous:
                        this.current = this.stream.Header.PreviousLsn;
                        break;
                    case LogRecordEnumeratorType.User: 
                        this.current = this.stream.Header.NextUndoLsn;
                        break; 
                } 
            }
 
            SequenceNumber first;
            SequenceNumber last;
            log.GetLogLimits(out first, out last);
            if (this.current < first 
                || last < this.current
                || this.current == SequenceNumber.Invalid) 
            { 
                this.record = null;
                return false; 
            }

            this.stream = new FileLogRecordStream(this.log, this.current);
 
            if (!this.enumRestartAreas && this.stream.Header.IsRestartArea)
            { 
                if (this.logRecordEnum == LogRecordEnumeratorType.Next) 
                {
                    // Move to the next record after restart area. 
                    return MoveNext();
                }
                else
                { 
                    // We have hit a restart area.
                    // Restart areas have special values for prev and next undo in the header. 
                    // Cannot enumerate further. 
                    this.record = null;
                    return false; 
                }
            }

            this.record = new FileLogRecord(this.stream); 
            return true;
        } 
 
        public void Reset()
        { 
            if (this.disposed)
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.ObjectDisposed());

            this.enumStarted = false; 
            this.current = this.start;
            this.record = null; 
        } 

        public void Dispose() 
        {
            this.disposed = true;
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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FileLogRecordEnumerator.cs source code in C# .NET

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