#85 StickyIterator

src/main/java/org/cactoos/list/EndlessIterator.java

@@ -24,6 +24,8 @@
 package org.cactoos.list;
 
 import java.util.Iterator;
+import org.cactoos.Scalar;
+import org.cactoos.func.UncheckedScalar;
 
 /**
  * Iterator that never ends.
@@ -41,13 +43,29 @@ public final class EndlessIterator<T> implements Iterator<T> {
     /**
      * The element to repeat.
      */
-    private final T element;
+    private final UncheckedScalar<T> element;
 
     /**
      * Ctor.
      * @param elm Element to repeat
      */
     public EndlessIterator(final T elm) {
+        this(() -> elm);
+    }
+
+    /**
+     * Ctor.
+     * @param elm Element to repeat
+     */
+    public EndlessIterator(final Scalar<T> elm) {
+        this(new UncheckedScalar<>(elm));
+    }
+
+    /**
+     * Ctor.
+     * @param elm Element to repeat
+     */
+    public EndlessIterator(final UncheckedScalar<T> elm) {
         this.element = elm;
     }
 
@@ -58,6 +76,6 @@ public boolean hasNext() {
 
     @Override
     public T next() {
-        return this.element;
+        return this.element.asValue();
     }
 }

src/main/java/org/cactoos/list/StickyIterable.java

@@ -30,7 +30,7 @@
 import org.cactoos.func.UncheckedScalar;
 
 /**
- * Iterable that returns an iterator only once.
+ * Iterable that returns the same set of elements, always.
  *
  * <p>There is no thread-safety guarantee.
  *

src/main/java/org/cactoos/list/StickyIterator.java

@@ -0,0 +1,76 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 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.list;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.LinkedList;
+import org.cactoos.func.StickyScalar;
+import org.cactoos.func.UncheckedScalar;
+
+/**
+ * Iterator that returns the same set of elements always.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Yegor Bugayenko (yegor256@gmail.com)
+ * @version $Id$
+ * @param <X> Type of item
+ * @since 0.8
+ */
+public final class StickyIterator<X> implements Iterator<X> {
+
+    /**
+     * The gate.
+     */
+    private final UncheckedScalar<Iterator<X>> gate;
+
+    /**
+     * Ctor.
+     * @param src The iterable
+     */
+    public StickyIterator(final Iterator<X> src) {
+        this.gate = new UncheckedScalar<>(
+            new StickyScalar<>(
+                () -> {
+                    final Collection<X> temp = new LinkedList<>();
+                    while (src.hasNext()) {
+                        temp.add(src.next());
+                    }
+                    return temp.iterator();
+                }
+            )
+        );
+    }
+
+    @Override
+    public boolean hasNext() {
+        return this.gate.asValue().hasNext();
+    }
+
+    @Override
+    public X next() {
+        return this.gate.asValue().next();
+    }
+}

src/test/java/org/cactoos/list/StickyIteratorTest.java

@@ -0,0 +1,68 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 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.list;
+
+import java.util.concurrent.atomic.AtomicInteger;
+import org.cactoos.Text;
+import org.cactoos.TextHasString;
+import org.cactoos.text.FormattedText;
+import org.hamcrest.MatcherAssert;
+import org.junit.Test;
+
+/**
+ * Test case for {@link StickyIterator}.
+ *
+ * @author Yegor Bugayenko (yegor256@gmail.com)
+ * @version $Id$
+ * @since 0.8
+ * @checkstyle JavadocMethodCheck (500 lines)
+ */
+public final class StickyIteratorTest {
+
+    @Test
+    public void ignoresChangesInIterable() throws Exception {
+        final AtomicInteger count = new AtomicInteger(2);
+        final Text text = new FormattedText(
+            "%s",
+            String.join(
+                ", ",
+                () -> new MappedIterator<>(
+                    new StickyIterator<>(
+                        new LimitedIterator<>(
+                            new EndlessIterator<>(count::incrementAndGet),
+                            2
+                        )
+                    ),
+                    Object::toString
+                )
+            )
+        );
+        MatcherAssert.assertThat(
+            "Can't ignore the changes in the underlying iterator",
+            text,
+            new TextHasString(text.asString())
+        );
+    }
+
+}