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;

    @SuppressWarnings("unchecked")
    public <T> T value() {
        return (T) value;
    }

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