package java_cup;

/** This class represents a part of a production which is a symbol (terminal
 *  or non terminal).  This simply maintains a reference to the symbol in 
 *  question.
 *
 * @see     java_cup.production
 * @version last updated: 11/25/95
 * @author  Scott Hudson
 */
public class symbol_part extends production_part {

    /*-----------------------------------------------------------*/
    /*--- Constructor(s) ----------------------------------------*/
    /*-----------------------------------------------------------*/

    /** Full constructor. 
     * @param sym the symbol that this part is made up of.
     * @param lab an optional label string for the part.
     */
    public symbol_part(symbol sym, String lab) throws internal_error {
        super(lab);

        if (sym == null)
            throw new internal_error("Attempt to construct a symbol_part with a null symbol");
        _the_symbol = sym;
    }

    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

    /** Constructor with no label. 
     * @param sym the symbol that this part is made up of.
     */
    public symbol_part(symbol sym) throws internal_error {
        this(sym, null);
    }

    /*-----------------------------------------------------------*/
    /*--- (Access to) Instance Variables ------------------------*/
    /*-----------------------------------------------------------*/

    /** The symbol that this part is made up of. */
    protected symbol _the_symbol;

    /** The symbol that this part is made up of. */
    public symbol the_symbol() {
        return _the_symbol;
    }

    /*-----------------------------------------------------------*/
    /*--- General Methods ---------------------------------------*/
    /*-----------------------------------------------------------*/

    /** Respond that we are not an action part. */
    @Override
    public boolean is_action() {
        return false;
    }

    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

    /** Equality comparison. */
    public boolean equals(symbol_part other) {
        return other != null && super.equals(other)
                && the_symbol().equals(other.the_symbol());
    }

    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

    /** Generic equality comparison. */
    @Override
    public boolean equals(Object other) {
        if (!(other instanceof symbol_part))
            return false;
        else return equals((symbol_part) other);
    }

    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

    /** Produce a hash code. */
    @Override
    public int hashCode() {
        return super.hashCode()
                ^ (the_symbol() == null ? 0 : the_symbol().hashCode());
    }

    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

    /** Convert to a string. */
    @Override
    public String toString() {
        if (the_symbol() != null)
            return super.toString() + the_symbol();
        else return super.toString() + "$$MISSING-SYMBOL$$";
    }

    /*-----------------------------------------------------------*/

}
