collections

README.md

@@ -22,7 +22,10 @@ There are a few design principles behind Cactoos:
 
   * No `null` ([why?](http://www.yegor256.com/2014/05/13/why-null-is-bad.html))
   * No code in constructors ([why?](http://www.yegor256.com/2015/05/07/ctors-must-be-code-free.html))
+  * No getters and setters ([why?](http://www.yegor256.com/2014/09/16/getters-and-setters-are-evil.html))
+  * No mutable objects ([why?](http://www.yegor256.com/2014/06/09/objects-should-be-immutable.html))
   * No `static` methods, not even `private` ones ([why?](http://www.yegor256.com/2017/02/07/private-method-is-new-class.html))
+  * No `instanceof`, type casting, or reflection ([why?](http://www.yegor256.com/2015/04/02/class-casting-is-anti-pattern.html))
   * No public methods without `@Override`
   * No statements in test methods except `assertThat` ([why?](http://www.yegor256.com/2017/05/17/single-statement-unit-tests.html))
 
@@ -105,11 +108,12 @@ To filter a collection:
 Collection<String> filtered = new IterableAsCollection(
   new FilteredIterable<>(
     new ArrayAsIterable("hello", "world", "dude"),
-    new Predicate() {
+    new Function<String, Boolean>() {
       @Override
-
+      public boolean apply(String i) {
+        return i.length() > 4;
+      }
     }
-    i -> i.length() > 4
   )
 );
 ```

src/main/java/org/cactoos/Func.java

@@ -0,0 +1,49 @@
+/**
+ * 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;
+
+import java.io.IOException;
+
+/**
+ * Function.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Yegor Bugayenko ([email protected])
+ * @version $Id$
+ * @param <X> Type of input
+ * @param <Y> Type of output
+ * @since 0.1
+ */
+public interface Func<X, Y> {
+
+    /**
+     * Apply it.
+     * @param input The argument
+     * @return The result
+     * @throws IOException If fails
+     */
+    Y apply(X input) throws IOException;
+
+}

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

@@ -0,0 +1,61 @@
+/**
+ * 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.Arrays;
+import java.util.Iterator;
+
+/**
+ * Array as iterable.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Yegor Bugayenko ([email protected])
+ * @version $Id$
+ * @param <X> Type of item
+ * @since 0.1
+ */
+public final class ArrayAsIterable<X> implements Iterable<X> {
+
+    /**
+     * The array.
+     */
+    private final X[] array;
+
+    /**
+     * Ctor.
+     * @param items The array
+     */
+    @SafeVarargs
+    @SuppressWarnings("varargs")
+    public ArrayAsIterable(final X... items) {
+        this.array = items;
+    }
+
+    @Override
+    public Iterator<X> iterator() {
+        return Arrays.asList(this.array).iterator();
+    }
+
+}

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

@@ -0,0 +1,74 @@
+/**
+ * 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.Arrays;
+import java.util.Iterator;
+
+/**
+ * A few Iterables joined together.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Yegor Bugayenko ([email protected])
+ * @version $Id$
+ * @param <T> Type of item
+ * @since 0.1
+ */
+public final class ConcatenatedIterable<T> implements Iterable<T> {
+
+    /**
+     * Iterables.
+     */
+    private final Iterable<Iterable<T>> list;
+
+    /**
+     * Ctor.
+     * @param items Items to concatenate
+     */
+    @SafeVarargs
+    @SuppressWarnings("varargs")
+    public ConcatenatedIterable(final Iterable<T>... items) {
+        this(Arrays.asList(items));
+    }
+
+    /**
+     * Ctor.
+     * @param items Items to concatenate
+     */
+    public ConcatenatedIterable(final Iterable<Iterable<T>> items) {
+        this.list = items;
+    }
+
+    @Override
+    public Iterator<T> iterator() {
+        return new ConcatenatedIterator<>(
+            new TransformedIterable<>(
+                this.list,
+                new StickyFunc<>(Iterable::iterator)
+            )
+        );
+    }
+
+}

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

@@ -0,0 +1,77 @@
+/**
+ * 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.Arrays;
+import java.util.Iterator;
+
+/**
+ * A few Iterables joined together.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Yegor Bugayenko ([email protected])
+ * @version $Id$
+ * @param <T> Type of item
+ * @since 0.1
+ */
+public final class ConcatenatedIterator<T> implements Iterator<T> {
+
+    /**
+     * Iterables.
+     */
+    private final Iterable<Iterator<T>> list;
+
+    /**
+     * Ctor.
+     * @param items Items to concatenate
+     */
+    @SafeVarargs
+    @SuppressWarnings("varargs")
+    public ConcatenatedIterator(final Iterator<T>... items) {
+        this(Arrays.asList(items));
+    }
+
+    /**
+     * Ctor.
+     * @param items Items to concatenate
+     */
+    public ConcatenatedIterator(final Iterable<Iterator<T>> items) {
+        this.list = items;
+    }
+
+    @Override
+    public boolean hasNext() {
+        return new FilteredIterable<>(
+            this.list, Iterator::hasNext
+        ).iterator().hasNext();
+    }
+
+    @Override
+    public T next() {
+        return new FilteredIterable<>(
+            this.list, Iterator::hasNext
+        ).iterator().next().next();
+    }
+}

src/main/java/org/cactoos/list/FilteredIterable.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.Iterator;
+import org.cactoos.Func;
+
+/**
+ * Filtered iterable.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Yegor Bugayenko ([email protected])
+ * @version $Id$
+ * @param <X> Type of item
+ * @since 0.1
+ */
+public final class FilteredIterable<X> implements Iterable<X> {
+
+    /**
+     * Iterable.
+     */
+    private final Iterable<X> iterable;
+
+    /**
+     * Function.
+     */
+    private final Func<X, Boolean> func;
+
+    /**
+     * Ctor.
+     * @param src Source iterable
+     * @param fnc Func
+     */
+    public FilteredIterable(final Iterable<X> src, final Func<X, Boolean> fnc) {
+        this.iterable = src;
+        this.func = fnc;
+    }
+
+    @Override
+    public Iterator<X> iterator() {
+        return new FilteredIterator<>(
+            this.iterable.iterator(), this.func
+        );
+    }
+
+}