(#1259) Sorted Set with custom comparator

README.md

@@ -236,6 +236,22 @@ final Iterable<String> sorted = new Sorted<>(
 );
 ```
 
+To create a sorted set from existing vararg elements using comparator:
+```java
+final Set<String> sorted = new org.cactoos.set.Sorted<>(
+    (first, second) -> first.compareTo(second),
+    "abc", "bcd", "abc", "ccc", "acd"
+);
+```
+
+To create a sorted set from existing iterable using comparator:
+```java
+final Set<String> sorted = new org.cactoos.set.Sorted<>(
+    (first, second) -> first.compareTo(second),
+    new IterableOf<>("abc", "bcd", "abc", "ccc", "acd")
+);
+```
+
 ## Funcs and Procs
 
 This is a traditional `foreach` loop:

src/main/java/org/cactoos/set/SetOf.java

@@ -23,10 +23,8 @@
  */
 package org.cactoos.set;
 
-import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
-import org.cactoos.collection.CollectionEnvelope;
 import org.cactoos.iterable.IterableOf;
 import org.cactoos.scalar.Unchecked;
 
@@ -42,7 +40,7 @@
  * @param <T> Set type
  * @since 0.49.2
  */
-public final class SetOf<T> extends CollectionEnvelope<T> implements Set<T> {
+public final class SetOf<T> extends SetEnvelope<T> {
 
     /**
      * Ctor.
@@ -64,7 +62,7 @@ public SetOf(final Iterable<T> src) {
                 () -> {
                     final Set<T> tmp = new HashSet<>();
                     src.forEach(tmp::add);
-                    return Collections.unmodifiableSet(tmp);
+                    return tmp;
                 }
             ).value()
         );

src/main/java/org/cactoos/set/Sorted.java

@@ -0,0 +1,72 @@
+/*
+ * 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.set;
+
+import java.util.Comparator;
+import java.util.Set;
+import java.util.TreeSet;
+import org.cactoos.iterable.IterableOf;
+import org.cactoos.scalar.Unchecked;
+
+/**
+ * Sorted Iterable as {@link Set}.
+ *
+ * <p>This class should be used very carefully. You must understand that
+ * it will fetch the entire content of the encapsulated {@link Set} on each
+ * method call. It doesn't cache the data anyhow. </p>
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @param <T> Set type
+ * @since 1.0.0
+ */
+public final class Sorted<T> extends SetEnvelope<T> {
+
+    /**
+     * Ctor.
+     * @param cmp Comparator
+     * @param array An array of some elements
+     */
+    @SafeVarargs
+    public Sorted(final Comparator<T> cmp, final T... array) {
+        this(cmp, new IterableOf<>(array));
+    }
+
+    /**
+     * Ctor.
+     * @param cmp Comparator
+     * @param src An {@link Iterable}
+     */
+    public Sorted(final Comparator<T> cmp, final Iterable<T> src) {
+        super(
+            new Unchecked<>(
+                () -> {
+                    final Set<T> set = new TreeSet<>(cmp);
+                    src.forEach(set::add);
+                    return set;
+                }
+            ).value()
+        );
+    }
+}

src/test/java/org/cactoos/set/SortedTest.java

@@ -0,0 +1,128 @@
+/*
+ * 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.set;
+
+import java.util.Comparator;
+import org.cactoos.Text;
+import org.cactoos.list.ListOf;
+import org.cactoos.text.TextOf;
+import org.cactoos.text.UncheckedText;
+import org.hamcrest.Matcher;
+import org.hamcrest.collection.IsIterableContainingInOrder;
+import org.hamcrest.core.IsEqual;
+import org.hamcrest.core.IsNot;
+import org.junit.Test;
+import org.llorllale.cactoos.matchers.Assertion;
+
+/**
+ * Test case for {@link Sorted}.
+ * @since 1.0.0
+ * @checkstyle MagicNumber (500 line)
+ * @checkstyle JavadocMethodCheck (500 lines)
+ * @checkstyle ClassDataAbstractionCouplingCheck (500 lines)
+ */
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
+public final class SortedTest {
+
+    @Test
+    public void mustSortIntegerArrayAsSetInAscendingOrder() {
+        new Assertion<>(
+            "Must keep unique integer numbers sorted",
+            new Sorted<>(
+                Integer::compareTo,
+                2, 1, 3, 2, 1
+            ),
+            new IsIterableContainingInOrder<>(
+                new ListOf<Matcher<? super Integer>>(
+                    new IsEqual<>(1),
+                    new IsEqual<>(2),
+                    new IsEqual<>(3)
+                )
+            )
+        ).affirm();
+    }
+
+    @Test
+    public void mustSortIntegerIterableAsSetInDescendingOrder() {
+        new Assertion<>(
+            "Must keep unique integer numbers sorted in descending order",
+            new Sorted<>(
+                Comparator.reverseOrder(),
+                2, 1, 3, 2, 1
+            ),
+            new IsIterableContainingInOrder<>(
+                new ListOf<Matcher<? super Integer>>(
+                    new IsEqual<>(3),
+                    new IsEqual<>(2),
+                    new IsEqual<>(1)
+                )
+            )
+        ).affirm();
+    }
+
+    @Test
+    public void mustSortTextIterableAsSetUsingCustomCOmparator() {
+        new Assertion<>(
+            "Must keep unique integer numbers sorted in descending order",
+            new Sorted<>(
+                (first, second) -> {
+                    final String left = new UncheckedText(first).asString();
+                    final String right = new UncheckedText(second).asString();
+                    return left.compareTo(right);
+                },
+                new TextOf("cd"),
+                new TextOf("ab"),
+                new TextOf("gh"),
+                new TextOf("ef")
+            ),
+            new IsIterableContainingInOrder<>(
+                new ListOf<Matcher<? super Text>>(
+                    new IsEqual<>(new TextOf("ab")),
+                    new IsEqual<>(new TextOf("cd")),
+                    new IsEqual<>(new TextOf("ef")),
+                    new IsEqual<>(new TextOf("gh"))
+                )
+            )
+        ).affirm();
+    }
+
+    @Test
+    public void mustNotBeEqualToSortedSet() {
+        new Assertion<>(
+            "Sorted set must not be equal to the tested collection",
+            new Sorted<>(
+                Integer::compareTo,
+                2, 1, 3, 2, 1
+            ),
+            new IsNot<>(
+                new IsIterableContainingInOrder<>(
+                    new ListOf<Matcher<? super Integer>>(
+                        new IsEqual<>(1),
+                        new IsEqual<>(3),
+                        new IsEqual<>(2)
+                    )
+                ))
+        ).affirm();
+    }
+}