org.tools4j.nobark.loop

Interface ComposableStep

All Superinterfaces:

Step

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface ComposableStep
extends Step

Extension of Step with enhanced functionality facilitating the composition of step chains.

Field Summary

Fields

Modifier and Type	Field and Description
static ComposableStep	NO_OP Step performing a no-OP; the implementation returns false indicating that no work was performed.

Method Summary

Modifier and Type	Method and Description
static ComposableStep	composite(Step... components) Returns a step that runs all given component steps; the Step.perform() method of the resulting composite step returns true if any of the component steps returns true.
static ComposableStep	create(Step step) Returns a composable step given a "normal" step.
default ComposableStep	then(Step next) Returns a composable step that performs first this and then the next step.
default ComposableStep	thenIfNotPerformed(Step next) Returns a composable step that performs first this step and then the next step only if the first performed no work as indicated by result of the Step.perform() invocation.
default ComposableStep	thenIfPerformed(Step next) Returns a composable step that performs first this step and then the next step only if the first performed any work as indicated by result of the Step.perform() invocation.

Methods inherited from interface org.tools4j.nobark.loop.Step

perform

Field Detail

NO_OP

static final ComposableStep NO_OP

Step performing a no-OP; the implementation returns false indicating that no work was performed. All composition methods are optimised to eliminate no-OP steps.

Method Detail

then

default ComposableStep then(Step next)

Returns a composable step that performs first this and then the next step.

The procedure eliminates no-OP steps, i.e. it returns this if (next == NO_OP).

Parameters:

next - the next step to be performed after this

Returns:

a composite step performing this and then next

thenIfPerformed

default ComposableStep thenIfPerformed(Step next)

Returns a composable step that performs first this step and then the next step only if the first performed any work as indicated by result of the Step.perform() invocation.

The procedure eliminates no-OP steps, i.e. it returns this if (next == NO_OP).

Parameters:

next - the next step to be performed after this only if it performed some work

Returns:

a composite step performing this, and if some work was performed subsequently also next

thenIfNotPerformed

default ComposableStep thenIfNotPerformed(Step next)

Returns a composable step that performs first this step and then the next step only if the first performed no work as indicated by result of the Step.perform() invocation.

The procedure eliminates no-OP steps, i.e. it returns this if (next == NO_OP).

Parameters:

next - the next step to be performed after this only if it performed no work

Returns:

a composite step performing this, and if no work was performed subsequently next

create

static ComposableStep create(Step step)

Returns a composable step given a "normal" step.

The procedure preserves no-OP steps as well as existing instances of ComposableStep, which means that such values are returned unchanged.

Parameters:

step - the step to be wrapped as a ComposableStep

Returns:

a ComposableStep doing exactly the same work as step but with a richer interface for step coposition

composite

static ComposableStep composite(Step... components)

Returns a step that runs all given component steps; the Step.perform() method of the resulting composite step returns true if any of the component steps returns true. The procedure uses then(Step) for the composition and eliminates no-OP components.

Parameters:

components - the component steps forming the parts of the returned step

Returns:

a new step that performs all component steps

See Also:

NO_OP