(yegor256#825) Binary class initial commit

src/main/java/org/cactoos/scalar/Binary.java

@@ -0,0 +1,78 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017-2018 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.scalar;
+
+import org.cactoos.Scalar;
+
+/**
+ * Binary  operation.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * <p>This class implements {@link Scalar}, which throws a checked
+ * {@link Exception}. This may not be convenient in many cases. To make
+ * it more convenient and get rid of the checked exception you can
+ * use the {@link UncheckedScalar} decorator. Or you may use
+ * {@link IoCheckedScalar} to wrap it in an IOException.</p>
+ *
+ * <pre>{@code
+ * new Binary<>(
+ *     5,
+ *     input -> input > 3,
+ *     input -> input = 8,
+ *     input -> input = 2
+ * ).value() // will be equal to 8
+ * }</pre>
+ */
+public final class Binary implements Scalar<Boolean> {
+
+    /**
+     * Scalar for condition
+     */
+    private final Scalar<Boolean> condition;
+    /**
+     * Runnable executed when condition is true
+     */
+    private final Runnable operation;
+
+    /**
+     * Ctor.
+     *
+     * @param condition Boolean function
+     * @param operation Runnable executed when condition is true
+     */
+    public Binary(Scalar<Boolean> condition, Runnable operation) {
+        this.condition = condition;
+        this.operation = operation;
+    }
+
+    @Override
+    public Boolean value() throws Exception {
+        final Boolean conditionResult = condition.value();
+        if (conditionResult) {
+            operation.run();
+        }
+        return conditionResult;
+    }
+}

src/main/java/org/cactoos/scalar/Ternary.java

@@ -48,6 +48,9 @@
  *
  * @param <T> Type of item.
  * @since 0.8
+ * @todo #825:30min Use Binary class in Ternary implementation.
+ *  When Binary class has been implemented we can use composition
+ *  for the internal Ternary implementation.
  */
 public final class Ternary<T> implements Scalar<T> {
 

src/test/java/org/cactoos/scalar/BinaryTest.java

@@ -0,0 +1,35 @@
+package org.cactoos.scalar;
+
+import org.cactoos.list.ListOf;
+import org.hamcrest.core.IsEqual;
+import org.junit.Test;
+import org.llorllale.cactoos.matchers.Assertion;
+import org.llorllale.cactoos.matchers.IsTrue;
+import org.llorllale.cactoos.matchers.ScalarHasValue;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Test case for {@link Binary}.
+ * @since 1.0
+ * @checkstyle JavadocMethodCheck (500 lines)
+ * @checkstyle MagicNumberCheck (500 lines)
+ */
+public class BinaryTest {
+
+    @Test
+    public void conditionTrue() {
+        final AtomicInteger atomicInteger = new AtomicInteger();
+        final Binary binary = new Binary(new True(), atomicInteger::incrementAndGet);
+        new Assertion<>(
+            "",
+            binary,
+            new IsTrue()
+        ).affirm();
+        new Assertion<>(
+            "",
+            atomicInteger::get,
+            new IsEqual<>(1)
+        ).affirm();
+    }
+}