org.stekikun.dolmen.unparam

Class Grammars.NTermsInfo

java.lang.Object

org.stekikun.dolmen.unparam.Grammars.NTermsInfo

Enclosing class:

Grammars

public static final class Grammars.NTermsInfo
extends Object

Gathers the result of the computation of the NULLABLE, FIRST and FOLLOW sets on non-terminals in a given grammar

Author:

Stéphane Lescuyer

Field Summary

Fields

Modifier and Type	Field and Description
Map<String,Set<String>>	first For each non-terminal X, the set of terminals that can begin strings derived from X
Map<String,Set<String>>	follow For each non-terminal X, the set of terminals which can follow X immediately in derived strings
Set<String>	nullable The set of nullable non-terminals, i.e. from which the empty string can be derived

Method Summary

Modifier and Type	Method and Description
Set<String>	first(Production prod)
Set<String>	first(String nterm)
Set<String>	follow(String nterm)
boolean	nullable(Production prod)
boolean	nullable(String nterm)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

nullable

public final Set<String> nullable

The set of nullable non-terminals, i.e. from which the empty string can be derived

first

public final Map<String,Set<String>> first

For each non-terminal X, the set of terminals that can begin strings derived from X

follow

public final Map<String,Set<String>> follow

For each non-terminal X, the set of terminals which can follow X immediately in derived strings

Method Detail

nullable

public boolean nullable(String nterm)

Parameters:

nterm -

Returns:

whether the non-terminal nterm is nullable

nullable

public boolean nullable(Production prod)

Parameters:

prod -

Returns:

whether the production prod is nullable

first

public Set<String> first(String nterm)

Parameters:

nterm -

Returns:

the set of terminals that can begin strings derived from the non-terminal nterm

Throws:

IllegalArgumentException - if nterm is not a known non-terminal

first

public Set<String> first(Production prod)

Parameters:

prod -

Returns:

the set of terminals that can begin strings derived from the given production prod

follow

public Set<String> follow(String nterm)

Parameters:

nterm -

Returns:

the set of terminals that can immediately follow nterm in derived strings

Throws:

IllegalArgumentException - if nterm is not a known non-terminal

toString

public String toString()

Overrides:

toString in class Object