java_cup

Class symbol

java.lang.Object

java_cup.symbol

Direct Known Subclasses:

non_terminal, terminal

public abstract class symbol
extends Object

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).

Version:

last updated: 11/25/95

Author:

Scott Hudson

See Also:

terminal, non_terminal

Field Summary

Fields

Modifier and Type	Field and Description
protected int	_index Index of this symbol (terminal or non terminal) in the parse tables.
protected String	_name String for the human readable name of the symbol.
protected String	_stack_type String for the type of object used for the symbol on the parse stack.
protected int	_use_count Count of how many times the symbol appears in productions.

Constructor Summary

Constructors

Constructor and Description
symbol(String nm) Constructor with default type.
symbol(String nm, String tp) Full constructor.

Method Summary

Methods

Modifier and Type	Method and Description
int	index() Index of this symbol (terminal or non terminal) in the parse tables.
abstract boolean	is_non_term() Indicate if this is a non-terminal.
String	name() String for the human readable name of the symbol.
void	note_use() Increment the use count.
String	stack_type() String for the type of object used for the symbol on the parse stack.
String	toString() Convert to a string.
int	use_count() Count of how many times the symbol appears in productions.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

_name

protected String _name

String for the human readable name of the symbol.

_stack_type

protected String _stack_type

String for the type of object used for the symbol on the parse stack.

_use_count

protected int _use_count

Count of how many times the symbol appears in productions.

_index

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.

Constructor Detail

symbol

public symbol(String nm,
      String tp)

Full constructor.

Parameters:

nm - the name of the symbol.

tp - a string with the type name.

symbol

public symbol(String nm)

Constructor with default type.

Parameters:

nm - the name of the symbol.

Method Detail

name

public String name()

String for the human readable name of the symbol.

stack_type

public String stack_type()

String for the type of object used for the symbol on the parse stack.

use_count

public int use_count()

Count of how many times the symbol appears in productions.

note_use

public void note_use()

Increment the use count.

index

public 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.

is_non_term

public abstract boolean is_non_term()

Indicate if this is a non-terminal. Here in the base class we don't know, so this is abstract.

toString

public String toString()

Convert to a string.

Overrides:

toString in class Object