package java_cup;
/**
* This abstract class serves as the base class for grammar symbols (i.e., both
* terminals and non-terminals). Each symbol has a name string, and a string
* giving the type of object that the symbol will be represented by on the
* runtime parse stack. In addition, each symbol maintains a use count in order
* to detect symbols that are declared but never used, and an index number that
* indicates where it appears in parse tables (index numbers are unique within
* terminals or non terminals, but not across both).
*
* @see java_cup.terminal
* @see java_cup.non_terminal
* @version last updated: 7/3/96
* @author Frank Flannery
*/
@SuppressWarnings (
{ "all" } )
public abstract class symbol
{
/*-----------------------------------------------------------*/
/*--- Constructor(s) ----------------------------------------*/
/*-----------------------------------------------------------*/
/**
* Full constructor.
*
* @param nm the name of the symbol.
* @param tp a string with the type name.
*/
public symbol ( String nm, String tp )
{
/* sanity check */
if ( nm == null )
nm = "";
/* apply default if no type given */
if ( tp == null )
tp = "Object";
_name = nm;
_stack_type = tp;
}
/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
/**
* Constructor with default type.
*
* @param nm the name of the symbol.
*/
public symbol ( String nm )
{
this ( nm, null );
}
/*-----------------------------------------------------------*/
/*--- (Access to) Instance Variables ------------------------*/
/*-----------------------------------------------------------*/
/** String for the human readable name of the symbol. */
protected String _name;
/** String for the human readable name of the symbol. */
public String name ()
{
return _name;
}
/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
/** String for the type of object used for the symbol on the parse stack. */
protected String _stack_type;
/** String for the type of object used for the symbol on the parse stack. */
public String stack_type ()
{
return _stack_type;
}
/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
/** Count of how many times the symbol appears in productions. */
protected int _use_count = 0;
/** Count of how many times the symbol appears in productions. */
public int use_count ()
{
return _use_count;
}
/** Increment the use count. */
public void note_use ()
{
_use_count++ ;
}
/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
/**
* Index of this symbol (terminal or non terminal) in the parse tables. Note:
* indexes are unique among terminals and unique among non terminals, however,
* a terminal may have the same index as a non-terminal, etc.
*/
protected int _index;
/**
* Index of this symbol (terminal or non terminal) in the parse tables. Note:
* indexes are unique among terminals and unique among non terminals, however,
* a terminal may have the same index as a non-terminal, etc.
*/
public int index ()
{
return _index;
}
/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
/**
* Indicate if this is a non-terminal. Here in the base class we don't know,
* so this is abstract.
*/
public abstract boolean is_non_term ();
/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
/** Convert to a string. */
public String toString ()
{
return name ();
}
/*-----------------------------------------------------------*/
}