net.jqwik.api.state

Interface Transformer<T>

Type Parameters:

T - The type of state to be transformed in a chain

All Superinterfaces:

java.util.function.Function<T,T>

Functional Interface:

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

@FunctionalInterface
 @API(status=EXPERIMENTAL,
     since="1.7.0")
public interface Transformer<T>
extends java.util.function.Function<T,T>

A transformer is used to transform a state of type T into another value of this type. Transformation can create a new object, or change the inner state of an object and return it.

In addition to performing a state transformation the mutator function can also check or assert conditions and invariants that should hold when doing the transformation. This is especially useful when a transformer is used as part of an action.

See Also:

Chain, Transformation, Action

Field Summary

Fields

Modifier and Type	Field and Description
static Transformer<?>	END_OF_CHAIN The singleton object used for all calls to endOfChain().
static Transformer<?>	NOOP The singleton object used for all calls to noop().

Method Summary

Modifier and Type	Method and Description
static <T> Transformer<T>	endOfChain() Use this transformer to stop further enhancement of a chain.
default boolean	isEndOfChain()
static <S> Transformer<S>	mutate(java.lang.String description, java.util.function.Consumer<S> mutate) Convenience method to create a transformer with a description.
static <T> Transformer<T>	noop() Use this transformer to signal a noop transformation.
static <S> Transformer<S>	transform(java.lang.String description, java.util.function.Function<S,S> transform) Create a transformer with a description
default java.lang.String	transformation() Describe the transformation this Transformer is doing in a human understandable way.

Methods inherited from interface java.util.function.Function

andThen, apply, compose, identity

Field Detail

END_OF_CHAIN

static final Transformer<?> END_OF_CHAIN

The singleton object used for all calls to endOfChain().

NOOP

static final Transformer<?> NOOP

The singleton object used for all calls to noop().

Method Detail

endOfChain

static <T> Transformer<T> endOfChain()

Use this transformer to stop further enhancement of a chain.

Whenever a endOfChain() is chosen by a chain, the chain ends with the current state being provided (e.g. in the chain's iterator) for a last time.

Type Parameters:

T - The transformer's state value type

Returns:

a transformer instance

noop

static <T> Transformer<T> noop()

Use this transformer to signal a noop transformation. This can be useful when a Transformation wants to provide a transformer that does nothing in some circumstances.

Noop transformers are ignored and not added to the chain of transformers.

Type Parameters:

T - The transformer's state value type

Returns:

a transformer instance

transform

static <S> Transformer<S> transform(java.lang.String description,
                                    java.util.function.Function<S,S> transform)

Create a transformer with a description

Type Parameters:

S - The type of the state to transform

Parameters:

description - A text to describe what the transform is doing

transform - The actual transforming function

Returns:

a new instance of a transformer

mutate

static <S> Transformer<S> mutate(java.lang.String description,
                                 java.util.function.Consumer<S> mutate)

Convenience method to create a transformer with a description. A mutator works on a mutable, stateful object which will always be returned.

Type Parameters:

S - The type of the state to mutate

Parameters:

description - A text to describe what the transform is doing

mutate - The actual mutating operation

Returns:

a new instance of a transformer

transformation

default java.lang.String transformation()

Describe the transformation this Transformer is doing in a human understandable way.

Returns:

non-empty String

isEndOfChain

default boolean isEndOfChain()