Merge branch '__rultor'

src/main/java/org/cactoos/collection/Sliced.java

@@ -0,0 +1,73 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017-2019 Yegor Bugayenko
+ *
+ * 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 NON-INFRINGEMENT. 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 org.cactoos.collection;
+
+import java.util.Collection;
+import org.cactoos.iterable.IterableOf;
+
+/**
+ * Sliced portion of the collection.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @param <T> Element type
+ * @since 1.0.0
+ */
+public final class Sliced<T> extends CollectionEnvelope<T> {
+
+    /**
+     * Ctor.
+     * @param start Starting index
+     * @param count Maximum number of elements for resulted iterator
+     * @param items Items
+     */
+    @SafeVarargs
+    public Sliced(final int start, final int count, final T... items) {
+        this(start, count, new IterableOf<>(items));
+    }
+
+    /**
+     * Ctor.
+     * @param start Starting index
+     * @param count Maximum number of elements for resulted iterator
+     * @param iterable Source iterable
+     */
+    public Sliced(final int start, final int count,
+        final Iterable<T> iterable) {
+        this(start, count, new CollectionOf<T>(iterable));
+    }
+
+    /**
+     * Ctor.
+     * @param start Starting index
+     * @param count Maximum number of elements for resulted iterator
+     * @param collection Source collection
+     */
+    public Sliced(final int start, final int count,
+        final Collection<T> collection) {
+        super(() -> new CollectionOf<T>(
+            new org.cactoos.iterable.Sliced<T>(start, count, collection)
+        ));
+    }
+}

src/main/java/org/cactoos/iterable/Sliced.java

@@ -0,0 +1,65 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017-2019 Yegor Bugayenko
+ *
+ * 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 NON-INFRINGEMENT. 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 org.cactoos.iterable;
+
+/**
+ * Sliced portion of the iterable.
+ *
+ * <p>There is no thread-safety guarantee.</p>
+ *
+ * @param <T> Element type
+ * @since 1.0.0
+ */
+public final class Sliced<T> extends IterableEnvelope<T>  {
+
+    /**
+     * Ctor.
+     * @param start Starting index
+     * @param count Maximum number of elements for resulted iterator
+     * @param items Varargs items
+     */
+    @SafeVarargs
+    public Sliced(final int start, final int count, final T... items) {
+        this(start, count, new IterableOf<>(items));
+    }
+
+    /**
+     * Ctor.
+     * @param start Starting index
+     * @param count Maximum number of elements for resulted iterator
+     * @param iterable Decorated iterable
+     */
+    public Sliced(final int start, final int count,
+        final Iterable<T> iterable) {
+        super(
+            new IterableOf<>(
+                () -> new org.cactoos.iterator.Sliced<>(
+                    start,
+                    count,
+                    iterable.iterator()
+                )
+            )
+        );
+    }
+}

src/main/java/org/cactoos/iterator/HeadOf.java

@@ -33,6 +33,9 @@
  *
  * @param <T> Element type
  * @since 0.8
+ * @todo #1188:30min Change the implementation of this class with the help of
+ *  <tt>org.cactoos.iterator.Sliced</tt> decorator, as it contains specific
+ *  constructor to build heading iterator.
  */
 public final class HeadOf<T> implements Iterator<T> {
 

src/main/java/org/cactoos/iterator/Partitioned.java

@@ -34,6 +34,9 @@
  *
  * @param <T> Partitions value type
  * @since 0.29
+ * @todo #1188:30min Change the implementation of this class with the help of
+ *  <tt>org.cactoos.iterator.Sliced</tt> decorator, to slice the original
+ *  iterator into sliced portions.
  */
 public final class Partitioned<T> implements Iterator<List<T>> {
 

src/main/java/org/cactoos/iterator/Skipped.java

@@ -33,6 +33,9 @@
  *
  * @param <T> Element type
  * @since 0.34
+ * @todo #1188:30min Change the implementation of this class with the help of
+ *  <tt>org.cactoos.iterator.Sliced</tt> decorator, as it contains specific
+ *  constructor to build skipped iterator.
  */
 public final class Skipped<T> implements Iterator<T> {
 

src/main/java/org/cactoos/iterator/Sliced.java

@@ -0,0 +1,127 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017-2019 Yegor Bugayenko
+ *
+ * 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 NON-INFRINGEMENT. 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 org.cactoos.iterator;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.function.IntPredicate;
+
+/**
+ * Creates an iterator returning an interval(slice) of the original iterator
+ * by means of providing starting index, number of elements to retrieve from
+ * the starting index and a decorated original iterator.
+ * Can be used to retrieve the head, tail or a portion in the middle of the
+ * original iterator.
+ *
+ * <p>There is no thread-safety guarantee.</p>
+ * @param <T> The type of the iterator.
+ * @since 1.0.0
+ * @todo #1188:30min This class to be refactored by extending IteratorEnvelope,
+ *  which will provide extra functionality to subclasses and is planned to be
+ *  added to Cactoos shortly.
+ */
+public final class Sliced<T> implements Iterator<T> {
+
+    /**
+     * Decorated iterator.
+     */
+    private final Iterator<T> iterator;
+
+    /**
+     * First index of the resulted iterator.
+     */
+    private final int start;
+
+    /**
+     * Current index on the original iterator.
+     */
+    private int current;
+
+    /**
+     * Predicate which tests whether the end has been reached.
+     */
+    private IntPredicate end;
+
+    /**
+     * Constructor.
+     * @param start Starting index
+     * @param count Maximum number of elements for resulted iterator
+     * @param iterator Decorated iterator
+     */
+    public Sliced(final int start, final int count,
+        final Iterator<T> iterator) {
+        this(start, index -> index > start + count - 1, iterator);
+    }
+
+    /**
+     * Constructor.
+     * Constructs an iterator of start position and up to the end
+     * @param start Starting index
+     * @param iterator Decorated iterator
+     */
+    public Sliced(final int start, final Iterator<T> iterator) {
+        this(start, any -> !iterator.hasNext(), iterator);
+    }
+
+    /**
+     * Constructor.
+     * @param start Starting index
+     * @param end Predicate that test whether iterating should stop
+     * @param iterator Decorated iterator
+     */
+    private Sliced(final int start, final IntPredicate end,
+        final Iterator<T> iterator) {
+        this.start = start;
+        this.end = end;
+        this.iterator = iterator;
+        this.current = 0;
+    }
+
+    @Override
+    public boolean hasNext() {
+        this.skip();
+        return !this.end.test(this.current) && this.iterator.hasNext();
+    }
+
+    @Override
+    public T next() {
+        if (!this.hasNext()) {
+            throw new NoSuchElementException(
+                "The iterator doesn't have items any more"
+            );
+        }
+        ++this.current;
+        return this.iterator.next();
+    }
+
+    /**
+     * Skips head elements up to start index.
+     */
+    private void skip() {
+        while (this.current < this.start && this.iterator.hasNext()) {
+            this.iterator.next();
+            ++this.current;
+        }
+    }
+}

src/test/java/org/cactoos/collection/SlicedTest.java

@@ -0,0 +1,55 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017-2019 Yegor Bugayenko
+ *
+ * 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 NON-INFRINGEMENT. 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 org.cactoos.collection;
+
+import org.hamcrest.core.IsEqual;
+import org.junit.Test;
+import org.llorllale.cactoos.matchers.Assertion;
+
+/**
+ * Test case for {@link Sliced}.
+ * @since 1.0.0
+ * @checkstyle JavadocMethodCheck (500 lines)
+ * @checkstyle MagicNumberCheck (500 lines)
+ */
+public final class SlicedTest {
+
+    @Test
+    @SuppressWarnings("PMD.AvoidDuplicateLiterals")
+    public void sliceCollection() {
+        new Assertion<>(
+            "Must get sliced collection",
+            new Sliced<>(
+                2,
+                2,
+                "one", "two", "three", "four"
+            ),
+            new IsEqual<>(
+                new CollectionOf<>(
+                    "three", "four"
+                )
+            )
+        ).affirm();
+    }
+}