/* Generated By:JavaCC: Do not edit this line. CharStream.java Version 0.7pre6 */

/**
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 * without modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright statements and notices. Redistributions
 * must also contain a copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 *
 * 3. The name "Exolab" must not be used to endorse or promote products derived from this Software
 * without prior written permission of Intalio, Inc. For written permission, please contact
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 * 4. Products derived from this Software may not be called "Exolab" nor may "Exolab" appear in
 * their names without prior written permission of Intalio, Inc. Exolab is a registered trademark of
 * Intalio, Inc.
 *
 * 5. Due credit should be given to the Exolab Project (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 2000 (C) Intalio Inc. All Rights Reserved.
 *
 * $Id$
 */

package org.exolab.castor.xml.dtd.parser;

/**
 * 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.
 * <p>
 * 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.
 *
 * @author Generated automatically by <b>JavaCC</b>
 * @version Version 0.7pre6
 */
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 :
   * 
   * <pre>
   * {
   *   String t = GetImage();
   *   return t.substring(t.length() - len, t.length()).toCharArray();
   * }
   * </pre>
   */
  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();

}
