Package beaver

Class Symbol

java.lang.Object

beaver.Symbol

All Implemented Interfaces:

Cloneable

Direct Known Subclasses:

ASTNode

public class Symbol
extends Object
implements Cloneable

Represents a symbol of a grammar.

Field Summary

Fields

Modifier and Type	Field	Description
protected int	end	Line and column where this symbol ends.
protected short	id	Numeric symbol ID.
protected int	start	Line and column where this symbol begins.
Object	value	Value assigned to this symbol.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Symbol()	Special case constructor that allows creation of explicitly Symbol-ized nonterminals.
	Symbol(short id)
	Symbol(short id, int start, int end)
	Symbol(short id, int start_line, int start_column, int length)
	Symbol(short id, int start_line, int start_column, int length, Object value)
	Symbol(short id, int left, int right, Object value)
	Symbol(short id, Object value)
	Symbol(Object value)	Creates Symbol for non-symbolic results of action routines

Method Summary

Modifier and Type	Method	Description
Symbol	clone()
static int	getColumn(int position)	Extracts column number from a packed position.
int	getEnd()	Returns a position in a source where this symbol ends.
short	getId()	Returns an ID of this symbol.
static int	getLine(int position)	Extracts line number from a packed position.
int	getStart()	Returns a position in a source where this symbol starts.
static int	makePosition(int line, int column)	Packs symbol "coordinates" into a single number.

Methods inherited from class java.lang.Object

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

Field Detail

value

public Object value

Value assigned to this symbol.

id

protected short id

Numeric symbol ID.

start

protected int start

Line and column where this symbol begins.

end

protected int end

Line and column where this symbol ends.

Constructor Detail

Symbol

public Symbol(short id)

Symbol

public Symbol(short id,
              Object value)

Symbol

public Symbol(short id,
              int start,
              int end)

Symbol

public Symbol(short id,
              int left,
              int right,
              Object value)

Symbol

public Symbol(short id,
              int start_line,
              int start_column,
              int length)

Symbol

public Symbol(short id,
              int start_line,
              int start_column,
              int length,
              Object value)

Symbol

public Symbol(Object value)

Creates Symbol for non-symbolic results of action routines

Parameters:

value - attached Symbol's value

Symbol

protected Symbol()

Special case constructor that allows creation of explicitly Symbol-ized nonterminals.

Used by classes descending from Symbol and which instances are returned by reduce actions. In this case ID and symbol position will be assigned by the parser when reduce action code returns this symbol.

Method Detail

makePosition

public static int makePosition(int line,
                               int column)

Packs symbol "coordinates" into a single number.

getLine

public static int getLine(int position)

Extracts line number from a packed position.

getColumn

public static int getColumn(int position)

Extracts column number from a packed position.

getId

public short getId()

Returns an ID of this symbol.

This ID typically is, depending on a symbol type, either a terminal ID if a Symbol is a token created and returned by a Scanner, or a nonterminal ID if a symbol was created by parser based on that nonterminal definition. In the former case the ID is one of IDs generated by Beaver for terminal symbols. The latter keeps IDs of nonterminal symbols.

Returns:

symbol's ID

getStart

public int getStart()

Returns a position in a source where this symbol starts.

Returns:

packed line and column numbers

getEnd

public int getEnd()

Returns a position in a source where this symbol ends.

Returns:

packed line and column numbers

clone

public Symbol clone()
             throws CloneNotSupportedException

Overrides:

clone in class Object

Throws:

CloneNotSupportedException