java_cup

Class non_terminal

public class non_terminal extends symbol

This class represents a non-terminal symbol in the grammar. Each non 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 pushed on the parse stack to represent it).

Version: last updated: 11/25/95

Author: Scott Hudson

Field Summary
boolean	is_embedded_action flag non-terminals created to embed action productions
protected static int	next_index Static counter to assign unique indexes.
protected static int	next_nt Static counter for creating unique non-terminal names
static non_terminal	START_nt special non-terminal for start symbol
protected static Hashtable	_all Table of all non-terminals -- elements are stored using name strings as the key
protected static Hashtable	_all_by_index Table of all non terminals indexed by their index number.
protected terminal_set	_first_set First set for this non-terminal.
protected boolean	_nullable Nullability of this non terminal.
protected Hashtable	_productions Table of all productions with this non terminal on the LHS.

Constructor Summary
	non_terminal(String nm, String tp) Full constructor.
	non_terminal(String nm) Constructor with default type.

Method Summary
void	add_production(production prod) Add a production to our set of productions.
static Enumeration	all() Access to all non-terminals.
static void	compute_first_sets() Compute first sets for all non-terminals.
static void	compute_nullability() Compute nullability of all non-terminals.
static non_terminal	find(String with_name) lookup a non terminal by name string
static non_terminal	find(int indx) Lookup a non terminal by index.
terminal_set	first_set() First set for this non-terminal.
boolean	is_non_term() Indicate that this symbol is a non-terminal.
protected boolean	looks_nullable() Test to see if this non terminal currently looks nullable.
boolean	nullable() Nullability of this non terminal.
static int	number() Total number of non-terminals.
int	num_productions() Total number of productions with this non terminal on the LHS.
Enumeration	productions() Access to productions with this non terminal on the LHS.
String	toString() convert to string