Collapse Maybe{Optional,Stream} into Maybe

This commit is contained in:
Paul Campbell 2018-06-25 22:04:23 +01:00
parent 7a150066a9
commit 2211182c7d
3 changed files with 62 additions and 134 deletions

View file

@ -24,7 +24,12 @@ package net.kemitix.mon.maybe;
import lombok.NonNull; import lombok.NonNull;
import net.kemitix.mon.Functor; import net.kemitix.mon.Functor;
import java.util.Optional;
import java.util.function.Consumer;
import java.util.function.Function; import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Stream;
/** /**
* A value that may or may not be present. * A value that may or may not be present.
@ -32,7 +37,8 @@ import java.util.function.Function;
* @param <T> the type of the content of the Just * @param <T> the type of the content of the Just
* @author Paul Campbell (pcampbell@kemitix.net) * @author Paul Campbell (pcampbell@kemitix.net)
*/ */
public interface Maybe<T> extends Functor<T, Maybe<?>>, MaybeStream<T>, MaybeOptional<T> { @SuppressWarnings("methodcount")
public interface Maybe<T> extends Functor<T, Maybe<?>> {
/** /**
* Create a Maybe for the value that may or may not be present. * Create a Maybe for the value that may or may not be present.
@ -72,4 +78,59 @@ public interface Maybe<T> extends Functor<T, Maybe<?>>, MaybeStream<T>, MaybeOpt
@Override @Override
<R> Maybe<R> map(Function<T, R> f); <R> Maybe<R> map(Function<T, R> f);
/**
* Provide a value to use when Maybe is Nothing.
*
* @param supplier supplier for an alternate value
* @return a Maybe
*/
T orElseGet(Supplier<T> supplier);
/**
* A value to use when Maybe is Nothing.
*
* @param otherValue an alternate value
* @return a Maybe
*/
T orElse(T otherValue);
/**
* Convert the Maybe to an {@link Optional}.
*
* @return an Optional containing a value for a Just, or empty for a Nothing
*/
Optional<T> toOptional();
/**
* Throw the exception if the Maybe is a Nothing.
*
* @param e the exception to throw
* @throws Exception if the Maybe is a Nothing
*/
@SuppressWarnings("illegalthrows")
void orElseThrow(Supplier<Exception> e) throws Exception;
/**
* Converts the Maybe into either a single value stream or and empty stream.
*
* @return a Stream containing the value or nothing.
*/
Stream<T> stream();
/**
* Filter a Maybe by the predicate, replacing with Nothing when it fails.
*
* @param predicate the test
* @return the Maybe, or Nothing if the test returns false
*/
Maybe<T> filter(Predicate<T> predicate);
/**
* Provide the value within the Maybe, if it exists, to the Supplier, and returns the Maybe.
*
* @param consumer the Consumer to the value if present
* @return the Maybe
*/
Maybe<T> peek(Consumer<T> consumer);
} }

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@ -1,71 +0,0 @@
/**
* The MIT License (MIT)
*
* Copyright (c) 2017 Paul Campbell
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
* and associated documentation files (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies
* or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package net.kemitix.mon.maybe;
import java.util.Optional;
import java.util.function.Supplier;
/**
* Enables emulation parts of and conversion to the Java Optional class for Maybe.
*
* @param <T> the type of the content of the Just
*
* @author Paul Campbell (pcampbell@kemitix.net)
*/
interface MaybeOptional<T> {
/**
* Provide a value to use when Maybe is Nothing.
*
* @param supplier supplier for an alternate value
*
* @return a Maybe
*/
T orElseGet(Supplier<T> supplier);
/**
* A value to use when Maybe is Nothing.
*
* @param otherValue an alternate value
*
* @return a Maybe
*/
T orElse(T otherValue);
/**
* Convert the Maybe to an {@link Optional}.
*
* @return an Optional containing a value for a Just, or empty for a Nothing
*/
Optional<T> toOptional();
/**
* Throw the exception if the Maybe is a Nothing.
*
* @param e the exception to throw
*
* @throws Exception if the Maybe is a Nothing
*/
@SuppressWarnings("illegalthrows")
void orElseThrow(Supplier<Exception> e) throws Exception;
}

View file

@ -1,62 +0,0 @@
/**
* The MIT License (MIT)
*
* Copyright (c) 2017 Paul Campbell
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
* and associated documentation files (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies
* or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package net.kemitix.mon.maybe;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Stream;
/**
* Enables emulation parts of and conversion to the Java Stream class for Maybe.
*
* @param <T> the type of the content of the Just
*
* @author Paul Campbell (pcampbell@kemitix.net)
*/
interface MaybeStream<T> {
/**
* Converts the Maybe into either a single value stream or and empty stream.
*
* @return a Stream containing the value or nothing.
*/
Stream<T> stream();
/**
* Filter a Maybe by the predicate, replacing with Nothing when it fails.
*
* @param predicate the test
*
* @return the Maybe, or Nothing if the test returns false
*/
Maybe<T> filter(Predicate<T> predicate);
/**
* Provide the value within the Maybe, if it exists, to the Supplier, and returns the Maybe.
*
* @param consumer the Consumer to the value if present
*
* @return the Maybe
*/
Maybe<T> peek(Consumer<T> consumer);
}