/* Generated By:JavaCC: Do not edit this line. CharStream.java Version 0.7pre6 */
/*
 * @(#)template.jj	1.0 00/04/20
 * 
 */
/* ======================================================================
The Bodington System Software License, Version 1.0
  
Copyright (c) 2001 The University of Leeds.  All rights reserved.
  
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
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1.  Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.

2.  Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
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3.  The end-user documentation included with the redistribution, if any,
must include the following acknowledgement:  "This product includes
software developed by the University of Leeds
(http://www.bodington.org/)."  Alternately, this acknowledgement may
appear in the software itself, if and wherever such third-party
acknowledgements normally appear.

4.  The names "Bodington", "Nathan Bodington", "Bodington System",
"Bodington Open Source Project", and "The University of Leeds" must not be
used to endorse or promote products derived from this software without
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=========================================================

This software was originally created by the University of Leeds and may contain voluntary 
contributions from others.  For more information on the Bodington Open Source Project, please 
see http://bodington.org/

====================================================================== */

package org.bodington.servlet.template;

/**
 * This interface describes a character stream that maintains line and
 * column number positions of the characters.  It also has the capability
 * to backup the stream to some extent.  An implementation of this
 * interface is used in the TokenManager implementation generated by
 * JavaCCParser.
 *
 * All the methods except backup can be implemented in any fashion. backup
 * needs to be implemented correctly for the correct operation of the lexer.
 * Rest of the methods are all used to get information like line number,
 * column number and the String that constitutes a token and are not used
 * by the lexer. Hence their implementation won't affect the generated lexer's
 * operation.
 */

abstract public interface CharStream {

  /**
   * Returns the next character from the selected input.  The method
   * of selecting the input is the responsibility of the class
   * implementing this interface.  Can throw any java.io.IOException.
   */
  abstract public char readChar() throws java.io.IOException;

  /**
   * Returns the column position of the character last read.
   * @deprecated 
   * @see #getEndColumn
   */
  abstract public int getColumn();

  /**
   * Returns the line number of the character last read.
   * @deprecated 
   * @see #getEndLine
   */
  abstract public int getLine();

  /**
   * Returns the column number of the last character for current token (being
   * matched after the last call to BeginTOken).
   */
  abstract public int getEndColumn();

  /**
   * Returns the line number of the last character for current token (being
   * matched after the last call to BeginTOken).
   */
  abstract public int getEndLine();

  /**
   * Returns the column number of the first character for current token (being
   * matched after the last call to BeginTOken).
   */
  abstract public int getBeginColumn();

  /**
   * Returns the line number of the first character for current token (being
   * matched after the last call to BeginTOken).
   */
  abstract public int getBeginLine();

  /**
   * Backs up the input stream by amount steps. Lexer calls this method if it
   * had already read some characters, but could not use them to match a
   * (longer) token. So, they will be used again as the prefix of the next
   * token and it is the implemetation's responsibility to do this right.
   */
  abstract public void backup(int amount);

  /**
   * Returns the next character that marks the beginning of the next token.
   * All characters must remain in the buffer between two successive calls
   * to this method to implement backup correctly.
   */
  abstract public char BeginToken() throws java.io.IOException;

  /**
   * Returns a string made up of characters from the marked token beginning 
   * to the current buffer position. Implementations have the choice of returning
   * anything that they want to. For example, for efficiency, one might decide
   * to just return null, which is a valid implementation.
   */
  abstract public String GetImage();

  /**
   * Returns an array of characters that make up the suffix of length 'len' for
   * the currently matched token. This is used to build up the matched string
   * for use in actions in the case of MORE. A simple and inefficient
   * implementation of this is as follows :
   *
   *   {
   *      String t = GetImage();
   *      return t.substring(t.length() - len, t.length()).toCharArray();
   *   }
   */
  abstract public char[] GetSuffix(int len);

  /**
   * The lexer calls this function to indicate that it is done with the stream
   * and hence implementations can free any resources held by this class.
   * Again, the body of this function can be just empty and it will not
   * affect the lexer's operation.
   */
  abstract public void Done();

}