com.illucit.partyinvoice.immutabledata

Class AbstractImmutableHolder<O extends Serializable,I extends Mutation<O,I>,H extends AbstractImmutableHolder<O,I,H>>

java.lang.Object

com.illucit.partyinvoice.immutabledata.AbstractImmutableHolder<O,I,H>

Type Parameters:

O - operation base class for Mutation

I - immutable data type (extends Mutation)

H - AbstractImmutableHolder implementation class

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

ImmutableProjectHolder

public abstract class AbstractImmutableHolder<O extends Serializable,I extends Mutation<O,I>,H extends AbstractImmutableHolder<O,I,H>>
extends Object
implements Serializable

Abstract implementation of a holder of an immutable object type, which supports mutations and undo/redo steps.

Author:

Christian Simon

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected H	redoStep
protected H	undoStep
protected I	value

Constructor Summary

Constructors

Modifier	Constructor and Description
	AbstractImmutableHolder() Create emtpy holder.
protected	AbstractImmutableHolder(H source, H newRedoStep) Create new holder functioning as undo step of a mutated holder state.
protected	AbstractImmutableHolder(H before, O operation) Create new holder state by performing an operation on a previous holder state.
protected	AbstractImmutableHolder(Supplier<I> supplier) Create holder containing the data from a Supplier.

Method Summary

Modifier and Type	Method and Description
protected abstract H	castSelf() Cast self (to implementor class <H>).
protected abstract I	createEmpty() Supplier for an empty value
protected I	getValue()
boolean	hasRedoStep() Check if project has step to redo.
boolean	hasUndoStep() Check if project has step to undo.
abstract H	operate(O operation) Perform operation (cast to implementor class).
H	redo() Return redo step for this.
H	undo() Return undo step for this.
protected abstract H	unwrap(H newRedoStep) Call the constructor AbstractImmutableHolder(AbstractImmutableHolder, AbstractImmutableHolder) implementation (of the implementor class <H>).

Methods inherited from class java.lang.Object

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

Field Detail

value

protected final I extends Mutation<O,I> value

undoStep

protected final H extends AbstractImmutableHolder<O,I,H> undoStep

redoStep

protected final H extends AbstractImmutableHolder<O,I,H> redoStep

Constructor Detail

AbstractImmutableHolder

public AbstractImmutableHolder()

Create emtpy holder.

AbstractImmutableHolder

protected AbstractImmutableHolder(Supplier<I> supplier)

Create holder containing the data from a Supplier.

Parameters:

supplier - supplier for the immutable data

AbstractImmutableHolder

protected AbstractImmutableHolder(H before,
                                  O operation)

Create new holder state by performing an operation on a previous holder state.

Parameters:

before - previous holder state

operation - operation to perform

AbstractImmutableHolder

protected AbstractImmutableHolder(H source,
                                  H newRedoStep)

Create new holder functioning as undo step of a mutated holder state. When a new state is created, the previous step cannot be used as undo step, as its redo step would not be the new created state. So the chain of undo steps needs to be put in new holder objects, where each one has the same immutable data as it had before, but the undo and redo steps are linked to a holder of the new chain.

Parameters:

source - the original holder object for this state

newRedoStep - the step that should be the new redo step of the created object

Method Detail

getValue

protected I getValue()

hasUndoStep

public boolean hasUndoStep()

Check if project has step to undo.

Returns:

true if undo can be performed

hasRedoStep

public boolean hasRedoStep()

Check if project has step to redo.

Returns:

true if redo can be performed

undo

public H undo()

Return undo step for this.

Returns:

step before

redo

public H redo()

Return redo step for this.

Returns:

step afterwards

createEmpty

protected abstract I createEmpty()

Supplier for an empty value

Returns:

empty value

castSelf

protected abstract H castSelf()

Cast self (to implementor class <H>).

Returns:

this as <H>

unwrap

protected abstract H unwrap(H newRedoStep)

Call the constructor AbstractImmutableHolder(AbstractImmutableHolder, AbstractImmutableHolder) implementation (of the implementor class <H>).

Parameters:

newRedoStep - holder state which should be the updated redo step of the unwrapped holder state

Returns:

new holder state

operate

public abstract H operate(O operation)

Perform operation (cast to implementor class).

Parameters:

operation - operation to perform

Returns:

changed state