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jnapejnape
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Union deforests
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5 files changed

+53
-24
lines changed

5 files changed

+53
-24
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‎src/main/java/com/jnape/palatable/lambda/iteration/UnioningIterable.java

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package com.jnape.palatable.lambda.iteration;
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import java.util.Iterator;
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import static com.jnape.palatable.lambda.functions.builtin.fn1.Distinct.distinct;
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public final class UnioningIterable<A> implements Iterable<A> {
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private final ConcatenatingIterable<A> elements;
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public UnioningIterable(Iterable<A> xs, Iterable<A> ys) {
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elements = new ConcatenatingIterable<>(xs instanceof UnioningIterable ? ((UnioningIterable<A>) xs).elements : xs,
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ys instanceof UnioningIterable ? ((UnioningIterable<A>) ys).elements : ys);
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}
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@Override
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public Iterator<A> iterator() {
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return distinct(elements).iterator();
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}
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}

‎src/main/java/com/jnape/palatable/lambda/monoid/builtin/Union.java

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package com.jnape.palatable.lambda.monoid.builtin;
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import com.jnape.palatable.lambda.functions.Fn1;
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import com.jnape.palatable.lambda.iteration.UnioningIterable;
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import com.jnape.palatable.lambda.monoid.Monoid;
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import java.util.Collections;
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import static com.jnape.palatable.lambda.functions.builtin.fn1.Distinct.distinct;
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import static com.jnape.palatable.lambda.monoid.builtin.Concat.concat;
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/**
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* Given two {@link Iterable}s, return the union of all unique occurrences of elements between them. Note that this
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* operation preserves order, so the unique elements of the first {@link Iterable} are iterated before the unique
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@Override
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public Iterable<A> apply(Iterable<A> xs, Iterable<A> ys) {
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return distinct(concat(xs, ys));
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return new UnioningIterable<>(xs, ys);
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}
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@SuppressWarnings("unchecked")

‎src/test/java/com/jnape/palatable/lambda/iteration/ConcatenatingIterableTest.java

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@@ -1,22 +1,15 @@
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package com.jnape.palatable.lambda.iteration;
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import com.jnape.palatable.lambda.functions.Fn1;
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import com.jnape.palatable.lambda.monoid.builtin.Concat;
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import com.jnape.palatable.traitor.annotations.TestTraits;
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import com.jnape.palatable.traitor.framework.Subjects;
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import com.jnape.palatable.traitor.runners.Traits;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import testsupport.traits.Deforesting;
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import static com.jnape.palatable.lambda.adt.Maybe.just;
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import static com.jnape.palatable.lambda.functions.builtin.fn1.Last.last;
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import static com.jnape.palatable.lambda.functions.builtin.fn1.Repeat.repeat;
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import static com.jnape.palatable.lambda.functions.builtin.fn2.Replicate.replicate;
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import static com.jnape.palatable.traitor.framework.Subjects.subjects;
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import static java.util.Arrays.asList;
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import static java.util.Collections.emptyList;
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import static org.junit.Assert.assertEquals;
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@RunWith(Traits.class)
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public class ConcatenatingIterableTest {
@@ -28,10 +21,4 @@ public Subjects<Fn1<Iterable<Integer>, Iterable<Integer>>> testSubject() {
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xs -> new ConcatenatingIterable<>(repeat(1), xs),
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xs -> new ConcatenatingIterable<>(xs, repeat(1)));
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}
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@Test
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public void stackSafety() {
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Iterable<Integer> xs = Concat.<Integer>concat().reduceLeft(replicate(1_000_000, asList(1, 2, 3)));
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assertEquals(just(3), last(xs));
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}
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}

‎src/test/java/com/jnape/palatable/lambda/iteration/UnioningIterableTest.java

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package com.jnape.palatable.lambda.iteration;
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import com.jnape.palatable.lambda.functions.Fn1;
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import com.jnape.palatable.traitor.annotations.TestTraits;
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import com.jnape.palatable.traitor.framework.Subjects;
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import com.jnape.palatable.traitor.runners.Traits;
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import org.junit.runner.RunWith;
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import testsupport.traits.Deforesting;
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import static com.jnape.palatable.lambda.functions.builtin.fn1.Repeat.repeat;
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import static com.jnape.palatable.traitor.framework.Subjects.subjects;
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import static java.util.Collections.emptyList;
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@RunWith(Traits.class)
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public class UnioningIterableTest {
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@TestTraits({Deforesting.class})
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public Subjects<Fn1<Iterable<Integer>, Iterable<Integer>>> testSubject() {
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return subjects(xs -> new UnioningIterable<>(emptyList(), xs),
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xs -> new UnioningIterable<>(xs, emptyList()),
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xs -> new UnioningIterable<>(repeat(1), xs),
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xs -> new UnioningIterable<>(xs, repeat(1)));
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}
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}

‎src/test/java/com/jnape/palatable/lambda/monoid/builtin/UnionTest.java

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import com.jnape.palatable.lambda.functions.Fn1;
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import com.jnape.palatable.traitor.annotations.TestTraits;
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import com.jnape.palatable.traitor.framework.Subjects;
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import com.jnape.palatable.traitor.runners.Traits;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import testsupport.traits.Deforesting;
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import testsupport.traits.EmptyIterableSupport;
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import testsupport.traits.FiniteIteration;
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import testsupport.traits.ImmutableIteration;
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import testsupport.traits.InfiniteIterableSupport;
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import testsupport.traits.Laziness;
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import static com.jnape.palatable.lambda.monoid.builtin.Union.union;
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import static com.jnape.palatable.traitor.framework.Subjects.subjects;
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import static java.util.Arrays.asList;
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import static java.util.Collections.emptyList;
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import static java.util.Collections.singletonList;
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@RunWith(Traits.class)
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public class UnionTest {
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@TestTraits({Laziness.class, InfiniteIterableSupport.class, EmptyIterableSupport.class, FiniteIteration.class, ImmutableIteration.class})
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public Fn1<Iterable<Integer>, Iterable<Integer>> testSubject() {
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return union(asList(1, 2, 3));
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@TestTraits({Laziness.class, InfiniteIterableSupport.class, EmptyIterableSupport.class, FiniteIteration.class, ImmutableIteration.class, Deforesting.class})
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public Subjects<Fn1<Iterable<Integer>, Iterable<Integer>>> testSubject() {
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return subjects(union(asList(1, 2, 3)), Union.<Integer>union().flip().apply(asList(1, 2, 3)));
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}
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@Test
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public void identity() {
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public void monoid() {
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assertThat(union().identity(), isEmpty());
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}
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@Test
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public void semigroup() {
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assertThat(union(emptyList(), emptyList()), isEmpty());
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assertThat(union(asList(1, 2), emptyList()), iterates(1, 2));
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assertThat(union(emptyList(), singletonList(3)), iterates(3));

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