Package io.atlassian.fugue

Class Options

java.lang.Object

io.atlassian.fugue.Options

public class Options
extends java.lang.Object

Utility methods for working with options.

Since:

1.1

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Options()

Method Summary

Modifier and Type	Method	Description
static <A,B> Option<B>	ap(Option<A> oa, Option<java.util.function.Function<A,B>> of)	Applies an option of A to an option of a function with input type A and result type B and return an option of B.
static <A> java.lang.Iterable<Option<A>>	filterNone(java.lang.Iterable<Option<A>> options)	Filter out undefined options.
static <A> Option<A>	find(java.lang.Iterable<Option<A>> options)	Find the first option that isDefined, or if there aren't any, then none.
static <A> java.lang.Iterable<A>	flatten(java.lang.Iterable<Option<A>> options)	Flattens an Iterable of options into an iterable of the things, filtering out any nones.
static <A,B> java.util.function.Function<java.util.function.Function<A,B>,java.util.function.Function<Option<A>,Option<B>>>	lift()	Returns a function that will lift a function that takes an A and returns a B into a function that takes an option of A and returns an option of B.
static <A,B> java.util.function.Function<Option<A>,Option<B>>	lift(java.util.function.Function<A,B> f)	Lifts a function that takes an A and returns a B into a function that takes an option of A and returns an option of B.
static <A> java.util.function.Predicate<Option<A>>	lift(java.util.function.Predicate<? super A> pred)	Lifts a predicate that takes an A into a predicate that takes an option of A.
static <A,B,C> java.util.function.Function<java.util.function.BiFunction<A,B,C>,java.util.function.BiFunction<Option<A>,Option<B>,Option<C>>>	lift2()	Returns a function that will lift a function that takes an A and a B and returns a C into a function that takes an option of A and an option of B and returns an option of C.
static <A,B,C> java.util.function.BiFunction<Option<A>,Option<B>,Option<C>>	lift2(java.util.function.BiFunction<A,B,C> f2)	Lifts a function that takes an A and a B and returns a C into a function that takes an option of A and an option of B and returns an option of C.
static <A,B> java.util.function.Function<A,Option<B>>	nullSafe(java.util.function.Function<A,B> nullProducing)	Turn a null producing function into one that returns an option instead.
static <A> java.util.function.Function<A,Option<A>>	toOption()	Function for wrapping values in a Some or None.
static <AA,A extends AA> Option<AA>	upcast(Option<A> o)	Upcasts an option of type A to an option of its super type AA.

Methods inherited from class java.lang.Object

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

Constructor Detail

Options

private Options()

Method Detail

find

public static <A> Option<A> find(java.lang.Iterable<Option<A>> options)

Find the first option that isDefined, or if there aren't any, then none.

Type Parameters:

A - the contained type

Parameters:

options - an Iterable of options to search through

Returns:

the first defined option, or none if there aren't any

upcast

public static <AA,A extends AA> Option<AA> upcast(Option<A> o)

Upcasts an option of type A to an option of its super type AA.

Type Parameters:

AA - the super type of the contained type

A - a A object.

Parameters:

o - the source option

Returns:

an option of the super type

Since:

2.0

lift

public static <A,B> java.util.function.Function<Option<A>,Option<B>> lift(java.util.function.Function<A,B> f)

Lifts a function that takes an A and returns a B into a function that takes an option of A and returns an option of B.

Type Parameters:

A - the input type of the original function

B - the result type of the original function

Parameters:

f - the original function to be lifted, must not be null

Returns:

a function that takes an option of type A and returns an option of type B

Since:

2.0

lift

public static <A,B> java.util.function.Function<java.util.function.Function<A,B>,java.util.function.Function<Option<A>,Option<B>>> lift()

Returns a function that will lift a function that takes an A and returns a B into a function that takes an option of A and returns an option of B.

Type Parameters:

A - the input type of the function that can be lifted

B - the result type of the function that can be lifted

Returns:

a function that can lift a function of input type A and result type B into Option

Since:

2.0

lift

public static <A> java.util.function.Predicate<Option<A>> lift(java.util.function.Predicate<? super A> pred)

Lifts a predicate that takes an A into a predicate that takes an option of A.

Type Parameters:

A - the input type of the predicate

Parameters:

pred - the original predicate to be lifted, must not be null

Returns:

a predicate that takes an option of type A

Since:

2.2

ap

public static <A,B> Option<B> ap(Option<A> oa,
                                       Option<java.util.function.Function<A,B>> of)

Applies an option of A to an option of a function with input type A and result type B and return an option of B.

Type Parameters:

A - the input type of the function wrapped in the option 'of'

B - the result type of the function wrapped in the option 'of'

Parameters:

oa - an option of the argument to the function

of - an option of a function that takes an A and returns a B

Returns:

an option of B

Since:

2.0

lift2

public static <A,B,C> java.util.function.BiFunction<Option<A>,Option<B>,Option<C>> lift2(java.util.function.BiFunction<A,B,C> f2)

Lifts a function that takes an A and a B and returns a C into a function that takes an option of A and an option of B and returns an option of C.

Type Parameters:

A - the input type of the first argument of the original function

B - the input type of the second argument of the original function

C - the result type of the original function

Parameters:

f2 - the original function to be lifted

Returns:

a function that takes an option of type A and an option of B and returns an option of type C

Since:

2.0

lift2

public static <A,B,C> java.util.function.Function<java.util.function.BiFunction<A,B,C>,java.util.function.BiFunction<Option<A>,Option<B>,Option<C>>> lift2()

Returns a function that will lift a function that takes an A and a B and returns a C into a function that takes an option of A and an option of B and returns an option of C.

Type Parameters:

A - the input type of the first argument of the function that can be lifted

B - the input type of the second argument of the function that can be lifted

C - the result type of the function that can be lifted

Returns:

a function that can lift a function of input type A and B and result type C into Option

Since:

2.0

filterNone

public static <A> java.lang.Iterable<Option<A>> filterNone(java.lang.Iterable<Option<A>> options)

Filter out undefined options.

Type Parameters:

A - the contained type

Parameters:

options - many options that may or may not be defined

Returns:

the filtered options

flatten

public static <A> java.lang.Iterable<A> flatten(java.lang.Iterable<Option<A>> options)

Flattens an Iterable of options into an iterable of the things, filtering out any nones.

Type Parameters:

A - the contained type

Parameters:

options - the iterable of options

Returns:

an Iterable of the contained type

toOption

public static <A> java.util.function.Function<A,Option<A>> toOption()

Function for wrapping values in a Some or None.

Type Parameters:

A - the contained type

Returns:

a Function to wrap values

Since:

3.0

nullSafe

public static <A,B> java.util.function.Function<A,Option<B>> nullSafe(java.util.function.Function<A,B> nullProducing)

Turn a null producing function into one that returns an option instead.

Type Parameters:

A - input type to the function.

B - output type of the function.

Parameters:

nullProducing - the function that may return null

Returns:

a function that turns nulls into None, and wraps non-null values in Some.

Since:

3.0