dk.rode.thesis.state
Enum ReversiblePrimeSequence.PrimeState

java.lang.Object
  java.lang.Enum<ReversiblePrimeSequence.PrimeState>
      dk.rode.thesis.state.ReversiblePrimeSequence.PrimeState

All Implemented Interfaces:

FunctionalState<Integer>, Serializable, Comparable<ReversiblePrimeSequence.PrimeState>

Enclosing class:

ReversiblePrimeSequence

private static enum ReversiblePrimeSequence.PrimeState
extends Enum<ReversiblePrimeSequence.PrimeState>
implements FunctionalState<Integer>

A prime state represents a stateless functional state for all reversible prime sequences, while the actual internal state and attributes are stored in a given reversible prime sequence instance.

State transitions are handled both by prime states, but also by reversible prime sequences requesting a given action, i.e. in ReversiblePrimeSequence.reverse().

Implementation notes:
Each state may be considered implemented according to the Flyweight pattern in that they are singletons that only operate on extrinsic state.

Author:

Gunni Rode / rode.dk

Enum Constant Summary

Calculate
Functional state calculating prime numbers for a reversible prime sequence, and delivering the next prime number (just calculated).

Next
Functional state delivering the next prime number for a reversible prime sequence ("forward"), where all prime numbers have been calculated.

Previous
Functional state delivering the previous prime number for a reversible prime sequence ("reverse"), where all prime numbers have been calculated.

ResetHigh
Functional state resetting a reversible prime sequence if prime numbers are delivered in descending order ("reverse").

ResetLow
Functional state resetting a reversible prime sequence to start over either because of initialisation, or in case of restart or reset explicitly if prime numbers are delivered in ascending order ("forward").

Start
Functional state initialising a reversible prime sequence.

Method Summary

protected abstract void	action(Sequence.State internalState, ReversiblePrimeSequence sequence) Handles the internal state request supplied as internalState for the reversible prime sequence supplied as sequence.
Integer	action(Sequence.State internalState, StateableSequence<Integer> sequence) Depending on the value of the internal state supplied as internalState, the following forms of actions are inferred: Sequence.State.START: initialisation requested.
static ReversiblePrimeSequence.PrimeState	valueOf(String name) Returns the enum constant of this type with the specified name.
static ReversiblePrimeSequence.PrimeState[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

Calculate

@Participant(value="ConcreteState")
public static final ReversiblePrimeSequence.PrimeState Calculate

Functional state calculating prime numbers for a reversible prime sequence, and delivering the next prime number (just calculated).

State transitions:

• Sequence.State.START: illegal state exception.

• Sequence.State.NORMAL: Next if all primes have been calculated.

• Sequence.State.RESET: ResetLow.

• Sequence.State.RESTART: illegal state exception.

See Also:

action(Sequence.State, ReversiblePrimeSequence)

Next

@Participant(value="ConcreteState")
public static final ReversiblePrimeSequence.PrimeState Next

Functional state delivering the next prime number for a reversible prime sequence ("forward"), where all prime numbers have been calculated.

State transitions:

• Sequence.State.START: illegal state exception.

• Sequence.State.NORMAL: ResetLow if restarting.

• Sequence.State.RESET: ResetLow.

• Sequence.State.RESTART: ResetLow.

Can also be set by ReversiblePrimeSequence.reverse().

See Also:

Previous, action(Sequence.State, ReversiblePrimeSequence)

Previous

@Participant(value="ConcreteState")
public static final ReversiblePrimeSequence.PrimeState Previous

Functional state delivering the previous prime number for a reversible prime sequence ("reverse"), where all prime numbers have been calculated.

State transitions:

• Sequence.State.START: illegal state exception.

• Sequence.State.NORMAL: ResetHigh if restarting.

• Sequence.State.RESET: ResetHigh.

• Sequence.State.RESTART: ResetHigh.

Can also be set by ReversiblePrimeSequence.reverse().

See Also:

Next, action(Sequence.State, ReversiblePrimeSequence)

ResetHigh

@Participant(value="ConcreteState")
public static final ReversiblePrimeSequence.PrimeState ResetHigh

Functional state resetting a reversible prime sequence if prime numbers are delivered in descending order ("reverse"). If so, all prime numbers have been calculated.

State transitions:

• Sequence.State.START: illegal state exception.

• Sequence.State.NORMAL: Previous.

• Sequence.State.RESET: None, but resets the sequence (high).

• Sequence.State.RESTART: None, but resets the sequence (high).

Can also be set by ReversiblePrimeSequence.reverse().

See Also:

ResetLow, action(Sequence.State, ReversiblePrimeSequence)

ResetLow

@Participant(value="ConcreteState")
public static final ReversiblePrimeSequence.PrimeState ResetLow

Functional state resetting a reversible prime sequence to start over either because of initialisation, or in case of restart or reset explicitly if prime numbers are delivered in ascending order ("forward").

State transitions:

• Sequence.State.START: initialises the reversible prime sequence the very first time (called from Start). Henceforth an illegal state exception is thrown if used again.

• Sequence.State.NORMAL: Calculate if all primes have not been calculated, otherwise Next.

• Sequence.State.RESET: None, but resets the sequence (low).

• Sequence.State.RESTART: None, but resets the sequence (low).

Can also be set by ReversiblePrimeSequence.reverse().

See Also:

ResetHigh, action(Sequence.State, ReversiblePrimeSequence)

Start

@Participant(value="ConcreteState")
public static final ReversiblePrimeSequence.PrimeState Start

Functional state initialising a reversible prime sequence. It is the first state set for any reversible prime sequence.

State transitions:

• Sequence.State.START: none, but initialises the sieve and validates the maximum number of primes to investigate. Once this state is discarded, it will never be used again for the same sequence.

• Sequence.State.NORMAL: Calculate if all primes have not been calculated, otherwise Next.

• Sequence.State.RESET: ResetLow.

• Sequence.State.RESTART: illegal state exception.

See Also:

action(Sequence.State, ReversiblePrimeSequence)

Method Detail

action

protected abstract void action(Sequence.State internalState,
                               ReversiblePrimeSequence sequence)

Handles the internal state request supplied as internalState for the reversible prime sequence supplied as sequence.

Parameters:

internalState - The internal state; never null, i.e. current state already handled at this point.

sequence - The reversible prime sequence in question; cannot be null.

Throws:

NullPointerException - If sequence is null.

action

public final Integer action(Sequence.State internalState,
                            StateableSequence<Integer> sequence)

Description copied from interface: FunctionalState

Depending on the value of the internal state supplied as internalState, the following forms of actions are inferred:

• Sequence.State.START: initialisation requested.

• Sequence.State.RESET: reset requested.

• Sequence.State.RESTART: restart requested.

• Sequence.State.NORMAL: next value requested.

• null: current value requested.

Specified by:

action in interface FunctionalState<Integer>

Parameters:

internalState - The internal state representing the requested action; can be null (current).

sequence - The stateable sequence in question; cannot be null.

Returns:

The sequence result from the action taken; can be null.

valueOf

public static ReversiblePrimeSequence.PrimeState valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

values

public static ReversiblePrimeSequence.PrimeState[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (ReversiblePrimeSequence.PrimeState c : ReversiblePrimeSequence.PrimeState.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared