[#101] Implemented rightOuterJoin

src/main/java/org/jooq/lambda/Seq.java

@@ -135,6 +135,20 @@ default <U> Seq<Tuple2<T, U>> leftOuterJoin(Stream<U> other, BiPredicate<T, U> p
                            .map(u -> tuple(t, u)));
     }
 
+    /**
+     * Right outer join 2 streams into one.
+     * <p>
+     * <code><pre>
+     * // (tuple(1, 1), tuple(2, 2), tuple(null, 3))
+     * Seq.of(1, 2).rightOuterJoin(Seq.of(1, 2, 3), t -> Objects.equals(t.v1, t.v2))
+     * </pre></code>
+     */
+    default <U> Seq<Tuple2<T, U>> rightOuterJoin(Stream<U> other, BiPredicate<T, U> predicate) {
+        return seq(other)
+              .leftOuterJoin(this, (u, t) -> predicate.test(t, u))
+              .map(t -> tuple(t.v2, t.v1));
+    }
+
     /**
      * Produce this stream, or an alternative stream from the
      * <code>value</code>, in case this stream is empty.

src/test/java/org/jooq/lambda/SeqTest.java

@@ -458,7 +458,7 @@ public void testInnerJoin() {
     }
 
     @Test
-    public void testLeftJoin() {
+    public void testLeftOuterJoin() {
         BiPredicate<Object, Object> TRUE = (t, u) -> true;
 
         assertEquals(asList(),
@@ -489,6 +489,42 @@ public void testLeftJoin() {
             Seq.<Object>of(1).leftOuterJoin(Seq.of(1, 2), TRUE).toList());
     }
 
+    @Test
+    public void testRightOuterJoin() {
+        BiPredicate<Object, Object> TRUE = (t, u) -> true;
+
+        assertEquals(asList(),
+            Seq.of().rightOuterJoin(Seq.of(), TRUE).toList());
+        assertEquals(asList(
+            tuple(null, 1)),
+            Seq.of().rightOuterJoin(Seq.of(1), TRUE).toList());
+        assertEquals(asList(
+            tuple(null, 1),
+            tuple(null, 2)),
+            Seq.of().rightOuterJoin(Seq.of(1, 2), TRUE).toList());
+
+        assertEquals(asList(),
+            Seq.<Object>of(1).rightOuterJoin(Seq.of(), TRUE).toList());
+        assertEquals(asList(
+            tuple(null, 2)),
+            Seq.of(1).rightOuterJoin(Seq.of(2), (t, u) -> t == u).toList());
+        assertEquals(asList(
+            tuple(1, 2)),
+            Seq.of(1).rightOuterJoin(Seq.of(2), (t, u) -> t * 2 == u).toList());
+        assertEquals(asList(
+            tuple(1, 1),
+            tuple(null, 2)),
+            Seq.of(1).rightOuterJoin(Seq.of(1, 2), (t, u) -> t == u).toList());
+        assertEquals(asList(
+            tuple(null, 1),
+            tuple(1, 2)),
+            Seq.of(1).rightOuterJoin(Seq.of(1, 2), (t, u) -> t * 2 == u).toList());
+        assertEquals(asList(
+            tuple(1, 1),
+            tuple(1, 2)),
+            Seq.<Object>of(1).rightOuterJoin(Seq.of(1, 2), TRUE).toList());
+    }
+
     @Test
     public void testOnEmpty() throws X {
         assertEquals(asList(1), Seq.of().onEmpty(1).toList());