/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Dreftool.
 *
 * The Initial Developer of the Original Code is
 * Rick Gessner <rick@gessner.com>.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Kenneth Herron <kjh-5727@comcast.net>
 *   Bernd Mielke <bmlk@gmx.de>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/**
 * MODULE NOTES:
 * @update  gess 4/1/98
 * 
 * The scanner is a low-level service class that knows
 * how to consume characters out of an (internal) stream.
 * This class also offers a series of utility methods
 * that most tokenizers want, such as readUntil(), 
 * readWhile() and SkipWhitespace().
 */


#ifndef CSCANNER_
#define CSCANNER_


#include "SharedTypes.h"
#include "nsString.h"
#include <fstream.h>


class  CScanner {
  public:


      /**
       *  Use this constructor if you want i/o to be stream based.
       *
       *  @update  gess 5/12/98
       *  @param   aMode represents the parser mode (nav, other)
       *  @return  
       */
      CScanner(istream& aStream);


      ~CScanner();

      /**
       *  retrieve next char from internal input stream
       *  
       *  @update  gess 3/25/98
       *  @param   ch is the char to accept new value
       *  @return  error code reflecting read status
       */
      int getChar(char& ch);

      /**
       *  peek ahead to consume next char from scanner's internal
       *  input buffer
       *  
       *  @update  gess 3/25/98
       *  @param   ch is the char to accept new value
       *  @return  error code reflecting read status
       */
      int peek(PRUnichar& ch);

      /**
       *  Push the given char back onto the scanner
       *  
       *  @update  gess 3/25/98
       *  @param   character to be pushed
       *  @return  error code
       */
      int push(PRUnichar ch);

      /**
       *  Determine if the scanner has reached EOF.
       *  This method can also cause the buffer to be filled
       *  if it happens to be empty
       *  
       *  @update  gess 3/25/98
       *  @return  true upon eof condition
       */
      int endOfFile(void);

      /**
       *  Consume characters until you find the terminal char
       *  
       *  @update  gess 3/25/98
       *  @param   aString receives new data from stream
       *  @param   aTerminal contains terminating char
       *  @param   addTerminal tells us whether to append terminal to aString
       *  @return  error code
       */
      int readUntil(nsAFlatCString& aString,PRUnichar aTerminal,bool addTerminal);

      /**
       *  Consume characters until you find one contained in given
       *  terminal set.
       *  
       *  @update  gess 3/25/98
       *  @param   aString receives new data from stream
       *  @param   aTermSet contains set of terminating chars
       *  @param   addTerminal tells us whether to append terminal to aString
       *  @return  error code
       */
      int readUntil(nsAFlatCString& aString,nsAFlatCString& aTermSet,bool addTerminal);

      /**
       *  Consume characters while they're members of anInputSet
       *  
       *  @update  gess 3/25/98
       *  @param   aString receives new data from stream
       *  @param   anInputSet contains valid chars
       *  @param   addTerminal tells us whether to append terminal to aString
       *  @return  error code
       */
      int readWhile(nsAFlatCString& aString,nsAFlatCString& anInputSet,bool addTerminal);


  protected:

      /**
       * Internal method used to cause the internal buffer to
       * be filled with data. 
       *
       * @update  gess4/3/98
       */
      int fillBuffer(void);


      istream&  mFileStream;
      nsCString mBuffer;
      int       mOffset;
      int       mTotalRead;
      bool      mIncremental;
};

#define kEOF  11111
#endif