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package java_cup;
import java_cup.assoc;
import java.util.Hashtable;
import java.util.Enumeration;
/** This class represents a terminal symbol in the grammar. Each terminal
* has a textual name, an index, and a string which indicates the type of
* object it will be implemented with at runtime (i.e. the class of object
* that will be returned by the scanner and pushed on the parse stack to
* represent it).
*
* @version last updated: 7/3/96
* @author Frank Flannery
*/
public class terminal extends symbol {
/*-----------------------------------------------------------*/
/*--- Constructor(s) ----------------------------------------*/
/*-----------------------------------------------------------*/
/** Full constructor.
* @param nm the name of the terminal.
* @param tp the type of the terminal.
*/
public terminal(String nm, String tp, int precedence_side, int precedence_num)
{
/* superclass does most of the work */
super(nm, tp);
/* add to set of all terminals and check for duplicates */
Object conflict = _all.put(nm,this);
if (conflict != null)
// can't throw an execption here because this is used in static
// initializers, so we do a crash instead
// was:
// throw new internal_error("Duplicate terminal (" + nm + ") created");
(new internal_error("Duplicate terminal (" + nm + ") created")).crash();
/* assign a unique index */
_index = next_index++;
/* set the precedence */
_precedence_num = precedence_num;
_precedence_side = precedence_side;
/* add to by_index set */
_all_by_index.put(new Integer(_index), this);
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Constructor for non-precedented terminal
*/
public terminal(String nm, String tp)
{
this(nm, tp, assoc.no_prec, -1);
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Constructor with default type.
* @param nm the name of the terminal.
*/
public terminal(String nm)
{
this(nm, null);
}
/*-----------------------------------------------------------*/
/*------------------- Class Variables ---------------------*/
/*-----------------------------------------------------------*/
private int _precedence_num;
private int _precedence_side;
/*-----------------------------------------------------------*/
/*--- (Access to) Static (Class) Variables ------------------*/
/*-----------------------------------------------------------*/
/** Table of all terminals. Elements are stored using name strings as
* the key
*/
protected static Hashtable _all = new Hashtable();
/** Access to all terminals. */
public static Enumeration all() {return _all.elements();}
/** Lookup a terminal by name string. */
public static terminal find(String with_name)
{
if (with_name == null)
return null;
else
return (terminal)_all.get(with_name);
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Table of all terminals indexed by their index number. */
protected static Hashtable _all_by_index = new Hashtable();
/** Lookup a terminal by index. */
public static terminal find(int indx)
{
Integer the_indx = new Integer(indx);
return (terminal)_all_by_index.get(the_indx);
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Total number of terminals. */
public static int number() {return _all.size();}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Static counter to assign unique index. */
protected static int next_index = 0;
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Special terminal for end of input. */
public static final terminal EOF = new terminal("EOF");
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** special terminal used for error recovery */
public static final terminal error = new terminal("error");
/*-----------------------------------------------------------*/
/*--- General Methods ---------------------------------------*/
/*-----------------------------------------------------------*/
/** Report this symbol as not being a non-terminal. */
public boolean is_non_term()
{
return false;
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Convert to a string. */
public String toString()
{
return super.toString() + "[" + index() + "]";
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** get the precedence of a terminal */
public int precedence_num() {
return _precedence_num;
}
public int precedence_side() {
return _precedence_side;
}
/** set the precedence of a terminal */
public void set_precedence(int p, int new_prec) {
_precedence_side = p;
_precedence_num = new_prec;
}
/*-----------------------------------------------------------*/
}
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