Add iterator.Paged and removve checkstyle suppression yegor256#1464

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

@@ -24,13 +24,8 @@
 package org.cactoos.iterable;
 
 import java.util.Iterator;
-import java.util.NoSuchElementException;
-import java.util.concurrent.atomic.AtomicReference;
 import org.cactoos.Func;
 import org.cactoos.Scalar;
-import org.cactoos.func.UncheckedFunc;
-import org.cactoos.scalar.Sticky;
-import org.cactoos.scalar.Unchecked;
 
 /**
  * Paged iterable.
@@ -41,11 +36,7 @@
  *
  * @param <X> Type of item
  * @since 0.47
- * @todo #1183:30m Continue refactoring and add `iterator.Paged` by
- *  extracting inner anon class from this class. The checkstyle suppression
- *  should be removed after that.
  */
-@SuppressWarnings("PMD.OnlyOneConstructorShouldDoInitialization")
 public final class Paged<X> extends IterableEnvelope<X> {
 
     /**
@@ -55,47 +46,12 @@ public final class Paged<X> extends IterableEnvelope<X> {
      * @param next Subsequent bags of elements
      * @param <I> Custom iterator
      */
-    @SuppressWarnings("PMD.ConstructorOnlyInitializesOrCallOtherConstructors")
     public <I extends Iterator<X>> Paged(
         final Scalar<I> first, final Func<I, I> next
     ) {
-        // @checkstyle AnonInnerLengthCheck (30 lines)
         super(
             new IterableOf<>(
-                () -> new Iterator<X>() {
-                    private final AtomicReference<Unchecked<I>> current =
-                        new AtomicReference<>(
-                            new Unchecked<>(
-                                new Sticky<>(first)
-                            )
-                        );
-
-                    private final UncheckedFunc<I, I> subsequent =
-                        new UncheckedFunc<>(next);
-
-                    @Override
-                    public boolean hasNext() {
-                        if (!this.current.get().value().hasNext()) {
-                            final I next = this.subsequent.apply(
-                                this.current.get().value()
-                            );
-                            this.current.set(
-                                new Unchecked<>(
-                                    new Sticky<>(() -> next)
-                                )
-                            );
-                        }
-                        return this.current.get().value().hasNext();
-                    }
-
-                    @Override
-                    public X next() {
-                        if (this.hasNext()) {
-                            return this.current.get().value().next();
-                        }
-                        throw new NoSuchElementException();
-                    }
-                }
+                new org.cactoos.iterator.Paged<>(first, next)
             )
         );
     }

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

@@ -0,0 +1,99 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017-2020 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.concurrent.atomic.AtomicReference;
+import org.cactoos.Func;
+import org.cactoos.Scalar;
+import org.cactoos.func.UncheckedFunc;
+import org.cactoos.scalar.Sticky;
+import org.cactoos.scalar.Unchecked;
+
+/**
+ * Paged iterator.
+ * Elements will continue to be provided so long as {@code next} produces
+ * non-empty iterators.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @param <I> Subtype of item iterator
+ * @param <X> Type of item
+ * @since 0.49
+ * @todo #1464:30min We want to use {@code Iterator<X>} directly in the class without
+ *  introducing I, maybe using {@code Iterator<? extends X>} for example because, we don't
+ *  have to constrain the {@link Func} to give exactly the same Iterator type as long as it
+ *  is an iterator that provides X. {@link org.cactoos.iterable.Paged} should be changed too.
+ */
+public final class Paged<I extends Iterator<X>, X> implements Iterator<X> {
+
+    /**
+     * Current element.
+     */
+    private final AtomicReference<Unchecked<I>> current;
+
+    /**
+     * Function to get the next element.
+     */
+    private final Func<I, I> subsequent;
+
+    /**
+     * Ctor.
+     * @param first First element.
+     * @param next Function to get the next element.
+     */
+    public Paged(final Scalar<I> first, final Func<I, I> next) {
+        this.current =
+            new AtomicReference<>(
+                new Unchecked<>(
+                    new Sticky<>(first)
+                )
+            );
+        this.subsequent = next;
+    }
+
+    @Override
+    public boolean hasNext() {
+        if (!this.current.get().value().hasNext()) {
+            final I next = new UncheckedFunc<>(this.subsequent).apply(
+                this.current.get().value()
+            );
+            this.current.set(
+                new Unchecked<>(
+                    new Sticky<>(() -> next)
+                )
+            );
+        }
+        return this.current.get().value().hasNext();
+    }
+
+    @Override
+    public X next() {
+        if (this.hasNext()) {
+            return this.current.get().value().next();
+        }
+        throw new NoSuchElementException();
+    }
+}