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Merge pull request #13 from kemitix/release-0.4.0

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Release 0.4.0
This commit is contained in:
Paul Campbell 2017-12-10 18:55:45 +00:00 committed by GitHub
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13 changed files with 522 additions and 55 deletions
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6
CHANGELOG
View file

@ -1,6 +1,12 @@
CHANGELOG
=========
0.4.0
-----
* Restore public access for `TypeAlias.getValue()`
* Add `Maybe`, `Just`, `Nothing`
0.3.0
-----

36
README.md
View file

@ -15,7 +15,7 @@ TypeAlias for Java
<dependency>
<groupId>net.kemitix</groupId>
<artifactId>mon</artifactId>
<version>0.3.0</version>
<version>0.4.0</version>
</dependency>
```
@ -41,3 +41,37 @@ void foo(final Goal goal) {
System.out.println("The goal is " + goal.getValue());
}
```
### Maybe (Just & Nothing)
```java
assertThat(Maybe.maybe(null)).isEqualTo(Maybe.nothing());
assertThat(Maybe.maybe(1)).isEqualTo(Maybe.just(1));
assertThat(Maybe.nothing()
.orElseGet(() -> 1)).isEqualTo(1);
assertThat(Maybe.just(1)
.orElseGet(() -> 2)).isEqualTo(1);
assertThat(Maybe.nothing()
.orElse(1)).isEqualTo(1);
assertThat(Maybe.just(1)
.orElse(2)).isEqualTo(1);
assertThat(Maybe.just(1)
.filter(v -> v > 2)).isEqualTo(Maybe.nothing());
assertThat(Maybe.just(3)
.filter(v -> v > 2)).isEqualTo(Maybe.just(3));
assertThat(Maybe.just(1)
.toOptional()).isEqualTo(Optional.of(1));
assertThat(Maybe.nothing()
.toOptional()).isEqualTo(Optional.empty());
assertThat(Maybe.fromOptional(Optional.of(1))).isEqualTo(Maybe.just(1));
assertThat(Maybe.fromOptional(Optional.empty())).isEqualTo(Maybe.nothing());
final AtomicInteger reference = new AtomicInteger(0);
assertThat(Maybe.just(1).peek(reference::set)).isEqualTo(Maybe.just(1));
assertThat(reference).hasValue(1);
assertThat(Maybe.nothing().peek(v -> reference.incrementAndGet())).isEqualTo(Maybe.nothing());
assertThat(reference).hasValue(1);
assertThatCode(() -> Maybe.just(1).orElseThrow(IllegalStateException::new))
.doesNotThrowAnyException();
assertThatThrownBy(() -> Maybe.nothing().orElseThrow(IllegalStateException::new))
.isInstanceOf(IllegalStateException.class);
```

2
pom.xml
View file

@ -10,7 +10,7 @@
<version>3.2.4</version>
</parent>
<artifactId>mon</artifactId>
<version>0.3.0</version>
<version>0.4.0</version>
<properties>
<junit.version>4.12</junit.version>

7
src/main/java/net/kemitix/mon/Functor.java
View file

@ -34,18 +34,19 @@ import java.util.function.Function;
* </ul>
*
* @param <T> the type of the Functor
* @param <F> the type of the mapped Functor
*
* @author Tomasz Nurkiewicz (?@?.?)
*/
public interface Functor<T> {
public interface Functor<T, F extends Functor<?, ?>> {
/**
* Applies the function to the value within the Functor, returning the result within a Functor.
*
* @param f the function to apply
* @param <R> the type of the result of the function
* @param <R> the type of the content of the mapped functor
*
* @return a Functor containing the result of the function {@code f} applied to the value
*/
<R> Functor<R> map(Function<T, R> f);
<R> F map(Function<T, R> f);
}

2
src/main/java/net/kemitix/mon/Identity.java
View file

@ -33,7 +33,7 @@ import java.util.function.Function;
* @author Paul Campbell (pcampbell@kemitix.net)
*/
@RequiredArgsConstructor
class Identity<T> implements Functor<T> {
class Identity<T> implements Functor<T, Identity<?>> {
private final T value;

94
src/main/java/net/kemitix/mon/Just.java Normal file
View file

@ -0,0 +1,94 @@
/**
* 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;
import lombok.AccessLevel;
import lombok.RequiredArgsConstructor;
import java.util.Objects;
import java.util.Optional;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
/**
* A Maybe where a value is present.
*
* @param <T> the type of the content
*
* @author Paul Campbell (pcampbell@kemitix.net)
*/
@RequiredArgsConstructor(access = AccessLevel.PROTECTED)
public final class Just<T> implements Maybe<T> {
private final T value;
@Override
public <R> Maybe<?> map(final Function<T, R> f) {
return new Just<>(f.apply(value));
}
@Override
public boolean equals(final Object other) {
return other instanceof Just && Objects.equals(this.value, ((Just) other).value);
}
@Override
public int hashCode() {
return Objects.hashCode(value);
}
@Override
public T orElseGet(final Supplier<T> supplier) {
return value;
}
@Override
public T orElse(final T otherValue) {
return this.value;
}
@Override
public Maybe<T> filter(final Predicate<T> predicate) {
if (predicate.test(value)) {
return this;
}
return Maybe.nothing();
}
@Override
public Optional<T> toOptional() {
return Optional.of(value);
}
@Override
public Maybe<T> peek(final Consumer<T> consumer) {
consumer.accept(value);
return this;
}
@Override
public void orElseThrow(final Supplier<Exception> e) {
// do not throw
}
}

145
src/main/java/net/kemitix/mon/Maybe.java Normal file
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@ -0,0 +1,145 @@
/**
* 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;
import lombok.NonNull;
import java.util.Optional;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.Supplier;
/**
* A value that may or may not be present.
*
* @param <T> the type of the content of the Just
*
* @author Paul Campbell (pcampbell@kemitix.net)
*/
public interface Maybe<T> extends Functor<T, Maybe<?>> {
/**
* Create a Maybe for the value that is present.
*
* @param value the value, not null
* @param <T> the type of the value
*
* @return a Maybe of the value
*/
static <T> Maybe<T> just(@NonNull final T value) {
return new Just<>(value);
}
/**
* Create a Maybe for a lack of a value.
*
* @param <T> the type of the missing value
*
* @return an empty Maybe
*/
@SuppressWarnings("unchecked")
static <T> Maybe<T> nothing() {
return (Maybe<T>) Nothing.INSTANCE;
}
/**
* Create a Maybe for the value that may or may not be present.
*
* @param value the value, may be null
* @param <T> the type of the value
*
* @return a Maybe, either a Just, or Nothing if value is null
*/
static <T> Maybe<T> maybe(final T value) {
if (value == null) {
return nothing();
}
return just(value);
}
/**
* Create a Maybe from an {@link Optional}.
*
* @param optional the Optional
* @param <T> the type of the Optional
*
* @return a Maybe
*/
static <T> Maybe<T> fromOptional(final Optional<T> optional) {
return optional.map(Maybe::maybe)
.orElse(nothing());
}
/**
* 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);
/**
* 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);
/**
* Convert the Maybe to an {@link Optional}.
*
* @return an Optional containing a value for a Just, or empty for a Nothing
*/
Optional<T> toOptional();
/**
* 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);
/**
* 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;
}

2
src/main/java/net/kemitix/mon/Mon.java
View file

@ -37,7 +37,7 @@ import java.util.function.Supplier;
* @author Paul Campbell (pcampbell@kemitix.net)
*/
@RequiredArgsConstructor(access = AccessLevel.PROTECTED)
public class Mon<T> implements Functor<T> {
public class Mon<T> implements Functor<T, Mon<?>> {
/**
* The value.

75
src/main/java/net/kemitix/mon/Nothing.java Normal file
View file

@ -0,0 +1,75 @@
/**
* 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;
import java.util.Optional;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
/**
* A Maybe where no value is present.
*
* @param <T> the type of the missing content
*
* @author Paul Campbell (pcampbell@kemitix.net)
*/
public final class Nothing<T> implements Maybe<T> {
protected static final Maybe<?> INSTANCE = new Nothing<>();
@Override
public <R> Maybe<?> map(final Function<T, R> f) {
return this;
}
@Override
public T orElseGet(final Supplier<T> supplier) {
return supplier.get();
}
@Override
public T orElse(final T otherValue) {
return otherValue;
}
@Override
public Maybe<T> filter(final Predicate<T> predicate) {
return this;
}
@Override
public Optional<T> toOptional() {
return Optional.empty();
}
@Override
public Maybe<T> peek(final Consumer<T> consumer) {
return this;
}
@Override
public void orElseThrow(final Supplier<Exception> e) throws Exception {
throw e.get();
}
}

25
src/main/java/net/kemitix/mon/TypeAlias.java
View file

@ -26,6 +26,9 @@ import java.util.function.Function;
/**
* Type Alias for other types.
*
* <p>{@link #toString()}, {@link #equals(Object)} and {@link #hashCode()} are all transparent, returning the value
* for the type being aliased.</p>
*
* @param <T> the type of the alias
*
* @author Paul Campbell (pcampbell@kemitix.net)
@ -38,20 +41,13 @@ public abstract class TypeAlias<T> {
*/
private final T value;
private final Class<? super T> type;
/**
* Constructor.
*
* @param value the value
* @param type the type of the value
*/
protected TypeAlias(
final T value,
final Class<? super T> type
) {
protected TypeAlias(final T value) {
this.value = value;
this.type = type;
}
/**
@ -72,14 +68,13 @@ public abstract class TypeAlias<T> {
}
@Override
@SuppressWarnings("unchecked")
public final boolean equals(final Object o) {
if (o instanceof TypeAlias) {
if (((TypeAlias) o).type.equals(type)) {
return ((TypeAlias<T>) o).map(getValue()::equals);
} else {
return false;
}
final TypeAlias other = (TypeAlias) o;
final Object otherValue = other.getValue();
final Class<?> otherValueClass = otherValue.getClass();
return otherValueClass.equals(getValue().getClass())
&& otherValue.equals(getValue());
}
return map(o::equals);
}
@ -94,7 +89,7 @@ public abstract class TypeAlias<T> {
*
* @return the value
*/
private T getValue() {
public T getValue() {
return value;
}
}

9
src/test/java/net/kemitix/mon/IdentityTest.java
View file

@ -10,15 +10,6 @@ import org.junit.Test;
*/
public class IdentityTest implements WithAssertions {
@Test
public void functorLawMapIdEqualsId() {
//given
final String id = "id";
//when
//then
}
@Test
public void canMapIdentityFromStringToInteger() {
//given

114
src/test/java/net/kemitix/mon/MaybeTest.java Normal file
View file

@ -0,0 +1,114 @@
package net.kemitix.mon;
import org.junit.Test;
import java.util.Objects;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Predicate;
import static net.kemitix.mon.Maybe.just;
import static net.kemitix.mon.Maybe.maybe;
import static net.kemitix.mon.Maybe.nothing;
import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatCode;
import static org.assertj.core.api.Assertions.assertThatNullPointerException;
import static org.assertj.core.api.Assertions.assertThatThrownBy;
public class MaybeTest {
private static <T> Predicate<T> eq(final T value) {
return v -> Objects.equals(value, v);
}
@Test
public void justMustBeNonNull() {
assertThatNullPointerException().isThrownBy(() -> just(null))
.withMessage("value");
}
@Test
public void nothingReusesTheSameInstance() {
assertThat(nothing()).isSameAs(nothing());
}
@Test
public void equality() {
assertThat(just(1)).isEqualTo(just(1));
assertThat(just(1)).isNotEqualTo(just(2));
assertThat(just(1)).isNotEqualTo(nothing());
assertThat(nothing()).isEqualTo(nothing());
assertThat(just(1).equals("1")).isFalse();
}
@Test
public void maybeAllowsNull() {
assertThat(just(1)).isEqualTo(maybe(1));
assertThat(nothing()).isEqualTo(maybe(null));
}
@Test
public void map() {
assertThat(just(1).map(v -> v + 1)).isEqualTo(just(2));
assertThat(nothing().map(v -> v)).isEqualTo(nothing());
}
@Test
public void testHashCode() {
assertThat(just(1).hashCode()).isEqualTo(Objects.hashCode(1));
}
@Test
public void orElseGet() {
assertThat(just(1).orElseGet(() -> -1)).isEqualTo(1);
assertThat(nothing().orElseGet(() -> -1)).isEqualTo(-1);
}
@Test
public void orElse() {
assertThat(just(1).orElse(-1)).isEqualTo(1);
assertThat(nothing().orElse(-1)).isEqualTo(-1);
}
@Test
public void filter() {
assertThat(just(1).filter(eq(1))).isEqualTo(just(1));
assertThat(just(1).filter(eq(0))).isEqualTo(nothing());
assertThat(nothing().filter(eq(1))).isEqualTo(nothing());
}
@Test
public void toOptional() {
assertThat(just(1).toOptional()).isEqualTo(Optional.of(1));
assertThat(nothing()
.toOptional()).isEqualTo(Optional.empty());
}
@Test
public void fromOptional() {
assertThat(Maybe.fromOptional(Optional.of(1))).isEqualTo(just(1));
assertThat(Maybe.fromOptional(Optional.empty())).isEqualTo(nothing());
}
@Test
public void peek() {
final AtomicInteger ref = new AtomicInteger(0);
assertThat(just(1).peek(x -> ref.incrementAndGet())).isEqualTo(just(1));
assertThat(ref.get()).isEqualTo(1);
assertThat(nothing().peek(x -> ref.incrementAndGet())).isEqualTo(nothing());
assertThat(ref.get()).isEqualTo(1);
}
@Test
public void justOrThrow() {
assertThatCode(() -> just(1).orElseThrow(IllegalStateException::new)).doesNotThrowAnyException();
}
@Test
public void nothingOrThrow() {
assertThatThrownBy(() -> nothing().orElseThrow(IllegalStateException::new)).isInstanceOf(
IllegalStateException.class);
}
}

60
src/test/java/net/kemitix/mon/TypeAliasTest.java
View file

@ -1,22 +1,29 @@
package net.kemitix.mon;
import org.assertj.core.util.Strings;
import org.junit.Test;
import java.util.Arrays;
import java.util.Collections;
import java.util.function.Function;
import java.util.List;
import static org.assertj.core.api.Assertions.assertThat;
public class TypeAliasTest {
@Test
public void shouldCreateATypeAliasAndGetTheValue() throws Exception {
public void shouldCreateATypeAliasAndGetTheValue() {
//given
final String value = "value";
//when
final TypeAlias<String> typeAlias = givenTypeAlias(value);
//then
assertThat(typeAlias.<Boolean>map(value::equals)).isTrue();
assertThat(typeAlias.getValue()).isSameAs(value);
}
private TypeAlias<String> givenTypeAlias(final String value) {
return new TypeAlias<String>(value) {
};
}
@Test
@ -25,38 +32,34 @@ public class TypeAliasTest {
final Iterable<String> iterable = Collections.emptyList();
//when
final TypeAlias<Iterable<String>> typeAlias =
new TypeAlias<Iterable<String>>(iterable, Iterable.class) {
new TypeAlias<Iterable<String>>(iterable) {
};
//then
assertThat(typeAlias.<Boolean>map(iterable::equals)).isTrue();
}
private TypeAlias<String> givenTypeAlias(final String value) {
return new TypeAlias<String>(value, String.class) {
};
assertThat(typeAlias.getValue()).isSameAs(iterable);
}
@Test
public void shouldCreateAnAliasedTypeAndGetTheValue() throws Exception {
public void shouldCreateATypeAliasSubclassAndGetTheValue() {
//given
final String value = "value";
//when
final AnAlias anAlias = AnAlias.of(value);
//then
assertThat(anAlias.<Boolean>map(value::equals)).isTrue();
assertThat(anAlias.getValue()).isSameAs(value);
}
@Test
public void shouldNotBeEqualWhenValueTypesAreDifferent() {
//given
final TypeAlias<String> stringTypeAlias = givenTypeAlias("1");
final TypeAlias<Integer> integerTypeAlias = new TypeAlias<Integer>(1, Integer.class){};
final TypeAlias<Integer> integerTypeAlias = new TypeAlias<Integer>(1) {
};
//then
assertThat(stringTypeAlias).isNotEqualTo(integerTypeAlias);
}
@Test
public void shouldBeEqualWhenValuesAreTheSame() throws Exception {
public void shouldBeEqualWhenValuesAreTheSame() {
//given
final String value = "value";
final AnAlias anAlias1 = AnAlias.of(value);
@ -66,7 +69,16 @@ public class TypeAliasTest {
}
@Test
public void shouldBeEqualToUnAliasedValue() throws Exception {
public void shouldNotBeEqualWhenValuesAreNotTheSame() {
//given
final AnAlias valueA = AnAlias.of("value a");
final AnAlias valueB = AnAlias.of("value b");
//then
assertThat(valueA).isNotEqualTo(valueB);
}
@Test
public void shouldBeEqualToRawValue() {
//given
final String value = "value";
final AnAlias anAlias = AnAlias.of(value);
@ -75,7 +87,7 @@ public class TypeAliasTest {
}
@Test
public void shouldHaveHashCodeOfValue() throws Exception {
public void shouldHaveHashCodeOfValue() {
//given
final String value = "value";
final AnAlias anAlias = AnAlias.of(value);
@ -84,24 +96,24 @@ public class TypeAliasTest {
}
@Test
public void shouldHaveSameToStringAsAliasedType() throws Exception {
public void shouldHaveSameToStringAsAliasedType() {
//given
final String value = "value";
final List<Integer> value = Arrays.asList(1, 2, 3);
//when
final AnAlias anAlias = AnAlias.of(value);
final TypeAlias<List<Integer>> anAlias = new TypeAlias<List<Integer>>(value) {
};
//then
assertThat(anAlias.toString()).isEqualTo(value);
assertThat(anAlias.toString()).isEqualTo(value.toString());
}
@Test
public void shouldMapTypeAlias() {
//given
final AnAlias anAlias = AnAlias.of("text");
final Function<String, String> function = v -> v;
//when
final String value = anAlias.map(function);
final String value = anAlias.map(Strings::quote);
//then
assertThat(value).isEqualTo("text");
assertThat(value).isEqualTo("'text'");
}
private static class AnAlias extends TypeAlias<String> {
@ -112,7 +124,7 @@ public class TypeAliasTest {
* @param value the value
*/
protected AnAlias(final String value) {
super(value, String.class);
super(value);
}
protected static AnAlias of(final String value) {