de.caff.generics

Class Union<T1,T2>

java.lang.Object

de.caff.generics.UnionBase<T1,T2>

de.caff.generics.Union<T1,T2>

Type Parameters:

T1 - type of the first possible value

T2 - type of the second possible value

public abstract class Union<T1,T2>
extends UnionBase<T1,T2>

This class defines a union structure for two exclusive values of different types.

This is sometimes useful to transport errors from one part to the other, when throwing them is no option. This is a type-safe implementation of a 2-member union structure as defined in the C programming language.

This class allows no overriding to guarantee the following invariances:

• u.has1() ^ u.has2() is always true

A union is immutable in the sense that it itself does not change. The contained values may change if they are mutable.

There is exactly one way to construct a union of either type:

• t1(Object) will construct a union which contains a value of type T1
• t2(Object) will construct a union which contains a value of type T2

This implementation does not allow null values. Any consumers can safely assume that the values they achieve are non-null. See NullableUnion if support for null is required.

Since:

July 26, 2024

Author:

Rammi

Method Summary

Modifier and Type	Method and Description
abstract T1	get1() Get the value if it is of type T1.
abstract T2	get2() Get the value if it is of type T2.
abstract java.lang.Object	getValue() Get the value contained in this union.
abstract void	handle(java.util.function.Consumer<? super T1> handler1, java.util.function.Consumer<? super T2> handler2) Call the appropriate handler depending on this unions' value.
abstract Union<T1,T2>	handle1(java.util.function.Consumer<? super T1> handler) Call the given handler if this union contains a value of type T1.
abstract Union<T1,T2>	handle2(java.util.function.Consumer<? super T2> handler) Call the given handler if this union contains a value of type T2.
abstract <E extends java.lang.Exception> Union<T1,T2>	handleFragile1(FragileProcedure1<E,? super T1> handler) Call the given handler if this union contains a value of type T1.
abstract <E extends java.lang.Exception> Union<T1,T2>	handleFragile2(FragileProcedure1<E,? super T2> handler) Call the given handler if this union contains a value of type T2.
abstract boolean	has1() Does this union contain a value of type T1?
abstract boolean	has2() Does this union contain a value of type T2?
static <V1,V2> Union<V1,V2>	t1(V1 v1) Create a union containing a value of type V1.
static <V1,V2> Union<V1,V2>	t2(V2 v2) Create a union containing a value of type V2.

Methods inherited from class de.caff.generics.UnionBase

isEqual1, isEqual2

Methods inherited from class java.lang.Object

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

Method Detail

has1

public abstract boolean has1()

Does this union contain a value of type T1?

Specified by:

has1 in class UnionBase<T1,T2>

Returns:

true: if this union contains a value of type T1
false: if this union contains a value of type T2

See Also:

get1()

has2

public abstract boolean has2()

Does this union contain a value of type T2?

Specified by:

has2 in class UnionBase<T1,T2>

Returns:

true: if this union contains a value of type T2
false: if this union contains a value of type T1

See Also:

get2()

get1

@NotNull
public abstract T1 get1()
                          throws java.lang.IllegalStateException

Get the value if it is of type T1. Throw an exception otherwise.

Specified by:

get1 in class UnionBase<T1,T2>

Returns:

value of type T1

Throws:

java.lang.IllegalStateException - if this union does contain a value of type T2

See Also:

has1()

get2

@NotNull
public abstract T2 get2()
                          throws java.lang.IllegalStateException

Get the value if it is of type T2. Throw an exception otherwise.

Specified by:

get2 in class UnionBase<T1,T2>

Returns:

value of type T2

Throws:

java.lang.IllegalStateException - if this union does contain a value of type T1

See Also:

has1()

getValue

@NotNull
public abstract java.lang.Object getValue()

Get the value contained in this union.

Specified by:

getValue in class UnionBase<T1,T2>

Returns:

the value of this union, having either type T1 or T2

handle

public abstract void handle(@NotNull
                            java.util.function.Consumer<? super T1> handler1,
                            @NotNull
                            java.util.function.Consumer<? super T2> handler2)

Call the appropriate handler depending on this unions' value.

Specified by:

handle in class UnionBase<T1,T2>

Parameters:

handler1 - called if this union contains a value of type T1

handler2 - called if this union contains a value of type T2

handle1

@NotNull
public abstract Union<T1,T2> handle1(@NotNull
                                              java.util.function.Consumer<? super T1> handler)

Call the given handler if this union contains a value of type T1.

Specified by:

handle1 in class UnionBase<T1,T2>

Parameters:

handler - called with the value of this union if the contained type is T1, not called otherwise

Returns:

this union for chaining

handle2

@NotNull
public abstract Union<T1,T2> handle2(@NotNull
                                              java.util.function.Consumer<? super T2> handler)

Call the given handler if this union contains a value of type T2.

Specified by:

handle2 in class UnionBase<T1,T2>

Parameters:

handler - called with the value of this union if the contained type is T2, not called otherwise

Returns:

this union for chaining

handleFragile1

@NotNull
public abstract <E extends java.lang.Exception> Union<T1,T2> handleFragile1(@NotNull
                                                                                     FragileProcedure1<E,? super T1> handler)
                                                                              throws E extends java.lang.Exception

Call the given handler if this union contains a value of type T1. Allows for a handler which might throw a checked exception.

Specified by:

handleFragile1 in class UnionBase<T1,T2>

Type Parameters:

E - exception the handler might throw

Parameters:

handler - called with the value of this union if the contained type is T1, not called otherwise

Returns:

this union for chaining

Throws:

E - if handler throws it

E extends java.lang.Exception

handleFragile2

@NotNull
public abstract <E extends java.lang.Exception> Union<T1,T2> handleFragile2(@NotNull
                                                                                     FragileProcedure1<E,? super T2> handler)
                                                                              throws E extends java.lang.Exception

Call the given handler if this union contains a value of type T2. Allows for a handler which might throw a checked exception.

Specified by:

handleFragile2 in class UnionBase<T1,T2>

Type Parameters:

E - exception the handler might throw

Parameters:

handler - called with the value of this union if the contained type is T2, not called otherwise

Returns:

this union for chaining

Throws:

E - if handler throws it

E extends java.lang.Exception

t1

@NotNull
public static <V1,V2> Union<V1,V2> t1(@NotNull
                                               V1 v1)

Create a union containing a value of type V1.

Type Parameters:

V1 - value type of contained value

V2 - implicit

Parameters:

v1 - value contained in this union

Returns:

union with value v1

t2

@NotNull
public static <V1,V2> Union<V1,V2> t2(@NotNull
                                               V2 v2)

Create a union containing a value of type V2.

Type Parameters:

V1 - implicit

V2 - value type of contained value

Parameters:

v2 - value contained in this union

Returns:

union with value v2