dk.rode.thesis.factorymethod
Class ReversibleSequenceCommandCreator<E>

java.lang.Object
  dk.rode.thesis.factorymethod.CommandCreator<E,Sequence.State>
      dk.rode.thesis.factorymethod.SequenceCommandCreator<E>
          dk.rode.thesis.factorymethod.ReversibleSequenceCommandCreator<E>

Type Parameters:

E - The type of values delivered by created commands (and thus sequences).

@Participant(value="ConcreteCreator")
public class ReversibleSequenceCommandCreator<E>
extends SequenceCommandCreator<E>

A reversible sequence command creator extends the sequence command creator to allow for the creation of reverse commands for reversible sequences.

This creator can create the following commands based on the supplied internal sequence state:

• null: a NullCommand is returned.

• Sequence.State.NORMAL: creates a new NextCommand instance (inherited functionality).

• Sequence.State.RESET: creates a new ResetCommand instance (inherited functionality).

• Sequence.State.RESTART: if the sequence is reversible, a new ReverseCommand instance is created and returned.

• Otherwise a LogCommand is returned (default).

A reversible sequence command creator is stateless and thread-safe.

Author:

Gunni Rode / rode.dk

Constructor Summary

ReversibleSequenceCommandCreator()
No-arg constructor.

Method Summary

protected Command<E>	create(Sequence<E> sequence, Sequence.State state) Factory method to create a new command of the type specified by the token supplied as token.
protected LogCommand<E>	createDefault(Sequence<E> sequence) Factory method to create a new default command in case the normal command creation failed.

Methods inherited from class dk.rode.thesis.factorymethod.CommandCreator

equals, getCommand, hashCode, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

ReversibleSequenceCommandCreator

public ReversibleSequenceCommandCreator()

No-arg constructor.

Method Detail

create

protected Command<E> create(Sequence<E> sequence,
                            Sequence.State state)
                     throws Exception

Description copied from class: CommandCreator

Factory method to create a new command of the type specified by the token supplied as token.

The sequence set as the receiver is supplied as sequence.

Overrides:

create in class SequenceCommandCreator<E>

Parameters:

sequence - The sequence; never null.

state - The token identifying the type of command to create; can be null.

Returns:

The corresponding command, or null if no such command could be created. If null is returned, a default (on null) command is returned by CommandCreator.getCommand(Sequence, Object).

Throws:

Exception - If the creation fails; if so, a default (or null) command will be returned by getCommand.

See Also:

CommandCreator.createDefault(Sequence)

createDefault

protected LogCommand<E> createDefault(Sequence<E> sequence)

Description copied from class: CommandCreator

Factory method to create a new default command in case the normal command creation failed.

Overrides:

createDefault in class CommandCreator<E,Sequence.State>

Parameters:

sequence - The sequence; never null.

Returns:

A new LogCommand instance; never null