package java_cup.runtime ;


/**
 * Defines the Symbol class, which is used to represent all terminals and
 * nonterminals while parsing. The lexer should pass CUP Symbols and CUP returns
 * a Symbol.
 * 
 * @version last updated: 7/3/96
 * @author Frank Flannery
 */
/*******************************************************************************
 * Class Symbol what the parser expects to receive from the lexer. the token is
 * identified as follows: sym: the symbol type parse_state: the parse state.
 * value: is the lexical value of type Object left : is the left position in the
 * original input file right: is the right position in the original input file
 * xleft: is the left position Object in the original input file xright: is the
 * left position Object in the original input file
 ******************************************************************************/
public class Symbol
{
  // TUM 20060327: Added new Constructor to provide more flexible way
  // for location handling
  /*******************************
   *******************************/
  public Symbol ( int id , Symbol left , Symbol right , Object o )
  {
    this ( id , left.left , right.right , o ) ;
  }


  public Symbol ( int id , Symbol left , Symbol right )
  {
    this ( id , left.left , right.right ) ;
  }


  /*****************************************************************************
   * Constructor for l,r values
   ****************************************************************************/
  public Symbol ( int id , int l , int r , Object o )
  {
    this ( id ) ;
    left = l ;
    right = r ;
    value = o ;
  }


  /*****************************************************************************
   * Constructor for no l,r values
   ****************************************************************************/
  public Symbol ( int id , Object o )
  {
    this ( id , - 1 , - 1 , o ) ;
  }


  /*****************************************************************************
   * Constructor for no value
   ****************************************************************************/
  public Symbol ( int id , int l , int r )
  {
    this ( id , l , r , null ) ;
  }


  /*****************************************************************************
   * Constructor for no value or l,r
   ****************************************************************************/
  public Symbol ( int sym_num )
  {
    this ( sym_num , - 1 ) ;
    left = - 1 ;
    right = - 1 ;
  }


  /*****************************************************************************
   * Constructor to give a start state
   ****************************************************************************/
  Symbol ( int sym_num , int state )
  {
    sym = sym_num ;
    parse_state = state ;
  }


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** The symbol number of the terminal or non terminal being represented */
  public int sym ;


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /**
   * The parse state to be recorded on the parse stack with this symbol. This
   * field is for the convenience of the parser and shouldn't be modified except
   * by the parser.
   */
  public int parse_state ;


  /**
   * This allows us to catch some errors caused by scanners recycling symbols.
   * For the use of the parser only. [CSA, 23-Jul-1999]
   */
  boolean used_by_parser = false ;


  /*****************************************************************************
   * The data passed to parser
   ****************************************************************************/
  public int left , right ;


  public Object value ;


  /*****************************************************************************
   * Printing this token out. (Override for pretty-print).
   ****************************************************************************/
  public String toString ( )
  {
    return "#" + sym ;
  }
}