org.stekikun.dolmen.debug

Class Derivation

java.lang.Object

org.stekikun.dolmen.debug.Derivation

Direct Known Subclasses:

Derivation.NonTerminal, Derivation.Terminal

public abstract class Derivation
extends Object

Instances of this class represent a derivation of some Grammar, i.e. a possible complete tree built from the grammar's productions and terminals.

A derivation can be displayed in its raw form, or in a more user-friendly fashion using append(Displayer, Appendable) and a custom Derivation.Displayer implementation.

Author:

Stéphane Lescuyer

See Also:

for how to produce derivations automatically

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Derivation.Displayer This interface is used by append(Displayer, Appendable) to allow the display of Derivation objects to be customized.
static class	Derivation.NonTerminal This represents a node in a Derivation tree, i.e. the realization of some non-terminal (symbol) in the grammar via one of its production (Derivation.NonTerminal.prod).
static class	Derivation.Terminal This represents a leaf in a Derivation tree, i.e. some terminal identified by its symbol number.

Field Summary

Fields

Modifier and Type	Field and Description
short	symbol The ordinal of the head symbol in this derivation, i.e. either the ordinal of the produced non-terminal, or of the leaf terminal.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Derivation(short symbol)

Method Summary

Modifier and Type	Method and Description
abstract void	append(Derivation.Displayer displayer, Appendable buf) Appends the representation of the receiver into buf using displayer
String	display(Grammar grammar)
abstract short	getHeight()
static Derivation.NonTerminal	production(short rule, short prod, List<Derivation> derivations)
static Derivation.Terminal	terminal(short token)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

symbol

public final short symbol

The ordinal of the head symbol in this derivation, i.e. either the ordinal of the produced non-terminal, or of the leaf terminal.

Constructor Detail

Derivation

protected Derivation(short symbol)

Method Detail

append

public abstract void append(Derivation.Displayer displayer,
                            Appendable buf)
                     throws IOException

Appends the representation of the receiver into buf using displayer

Parameters:

displayer -

buf -

Throws:

IOException

getHeight

public abstract short getHeight()

Returns:

the height of the derivation

toString

public String toString()

Overrides:

toString in class Object

display

public String display(Grammar grammar)

Parameters:

grammar -

Returns:

a user-friendly representation of the derivation using the symbols of the given grammar

production

public static Derivation.NonTerminal production(short rule,
                                                short prod,
                                                List<Derivation> derivations)

Parameters:

rule -

prod -

derivations -

Returns:

the derivation for the non-terminal rule using the production prod and the given sub-derivations

terminal

public static Derivation.Terminal terminal(short token)

Parameters:

token -

Returns:

the leaf derivation representing the given token