/*

* Copyright (c) 2004-2008 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

using System;

using System.IO;

using System.Text;

using System.Collections;

using System.Diagnostics;

namespace SymBuildParsingLib

{

	#region Exceptions

	public class SymParserStreamExceptionInvalidRewindAmount : Exception

	{

		public SymParserStreamExceptionInvalidRewindAmount( string aMessage )

			: base( aMessage )

		{

		}

	}

	#endregion

	public class SymStream

	{

		#region Constructors & destructor

		public SymStream( string aFileName )

		{

			iFileName = aFileName;

			iFileStream = new FileStream( aFileName, System.IO.FileMode.Open );

			iStream = new StreamReader( iFileStream );

			iFileData = new Stack( 1024 * 20 );

		}

		#endregion

		#region API

		public char PeekChar()

		{

			Debug.Assert( !EOF );

			//

			char ret = (char) iStream.Peek();

			//

			if	( iPushedBackCharacters.Count > 0 )

			{

				ret = (char) iPushedBackCharacters.Peek();

			}

			return ret;

		}

		public char ReadChar()

		{

			Debug.Assert( !EOF );

			//

			char ret;

			//

			if	( iPushedBackCharacters.Count > 0 )

			{

				ret = (char) iPushedBackCharacters.Pop();

			}

			else

			{

				ret = (char) iStream.Read();

			}

			//

			iFileData.Push( ret );

			++iPosition;

			//

			return ret;

		}

		public void RewindChar()

		{

			RewindChars( 1 );

		}

		public void RewindChars( int aRewindCount )

		{

			long newPos = Position - aRewindCount;

			if	( aRewindCount < 0 )

				throw new SymParserStreamExceptionInvalidRewindAmount( "Rewind specifier must be >= 0" );

			else if ( newPos < 0 || newPos >= Size ) 

				throw new SymParserStreamExceptionInvalidRewindAmount( "Rewind specifier takes stream position beyond scope of file" );

			for( int i=0; i<aRewindCount; i++ )

			{

				char character = (char) iFileData.Pop();

				iPushedBackCharacters.Push( character );

			}

			iPosition -= aRewindCount;

		}

		#endregion

		#region Properties

		public string FileName

		{

			get { return iFileName; }

		}

		public long Position

		{

			get { return iPosition; }

		}

		public long Size

		{

			get { return iStream.BaseStream.Length; }

		}

		public bool EOF

		{

			get

			{

				long fileSize = Size;

				bool atEnd = ( Position >= fileSize );

				return atEnd;

			}

		}

		#endregion

		#region Constants

		private const int KStreamEOF = -1;

		#endregion

		#region Data members

		private readonly string iFileName;

		private StreamReader iStream;

		private FileStream iFileStream;

		private Stack iPushedBackCharacters = new Stack( 1024 );

		private Stack iFileData;

		private long iPosition;

		#endregion

	}

}