Package org.extendj.neobeaver

Class Item

java.lang.Object

org.extendj.neobeaver.Item

public class Item
extends java.lang.Object

An Item is a parsing rule with a dot at the current symbol position. LR1 rules have an additional lookahead symbol.

Field Summary

Fields

Modifier and Type	Field	Description
int	dot
java.util.Set<Symbol>	follow
Rule	rule
java.util.List<Item>	succ

Constructor Summary

Constructors

Constructor	Description
Item(Rule rule, int dot, Symbol... follows)

Method Summary

Modifier and Type	Method	Description
void	addFollow(Symbol sym)
void	addFollows(java.util.Collection<Symbol> sym)
void	addToFollowSet(java.util.Map<Symbol,Tuple<Symbol,ItemSet>> map)	Add the item set following this one to the follow set argument.
Item	advance()
Symbol	afterDot()
Item	baseItem()	Gives an item identical to this one but without follow symbol.
boolean	canAdvance()
boolean	equals(java.lang.Object obj)
java.util.Collection<Symbol>	followSyms()
int	hashCode()
java.util.Collection<Item>	immediateExtension(Grammar grammar)
boolean	nullable(Grammar grammar)	Returns true if this item is nullable.
boolean	nullableAfter(int pos, Grammar grammar)	Returns true if the symbols after the given position form a nullable sentence.
java.util.Collection<Tuple3<ItemSet,Symbol,Action>>	reduceActions(Grammar grammar, ItemSet set)
boolean	related(Symbol sym)	Returns true if the this item is related to a conflict on symbol sym.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

rule

public final Rule rule

dot

public final int dot

follow

public final java.util.Set<Symbol> follow

succ

public java.util.List<Item> succ

Constructor Detail

Item

public Item(Rule rule,
            int dot,
            Symbol... follows)

Method Detail

addFollow

public void addFollow(Symbol sym)

addFollows

public void addFollows(java.util.Collection<Symbol> sym)

addToFollowSet

public void addToFollowSet(java.util.Map<Symbol,Tuple<Symbol,ItemSet>> map)

Add the item set following this one to the follow set argument.

Parameters:

map - a map of follow sets, indexed by the lookahead symbol

immediateExtension

public java.util.Collection<Item> immediateExtension(Grammar grammar)

nullable

public boolean nullable(Grammar grammar)

Returns true if this item is nullable.

nullableAfter

public boolean nullableAfter(int pos,
                             Grammar grammar)

Returns true if the symbols after the given position form a nullable sentence.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

canAdvance

public boolean canAdvance()

afterDot

public Symbol afterDot()

advance

public Item advance()

baseItem

public Item baseItem()

Gives an item identical to this one but without follow symbol.

reduceActions

public java.util.Collection<Tuple3<ItemSet,Symbol,Action>> reduceActions(Grammar grammar,
                                                                                     ItemSet set)

followSyms

public java.util.Collection<Symbol> followSyms()

related

public boolean related(Symbol sym)

Returns true if the this item is related to a conflict on symbol sym.