Seq: Get unique values of sequence

src/Seq.php

@@ -129,4 +129,31 @@ public static function map(iterable $traversable, callable $callback): Generator
             yield $key => $callback($value);
         }
     }
+
+    /**
+     * Yield every unique value of the given traversable with its original key
+     *
+     * @param iterable $traversable
+     * @param bool $caseSensitive
+     *
+     * @return Generator
+     */
+    public static function unique(iterable $traversable, bool $caseSensitive = true): Generator
+    {
+        $seen = [];
+        foreach ($traversable as $key => $value) {
+            if (is_string($value)) {
+                $needle = $caseSensitive ? $value : strtolower($value);
+            } elseif (is_object($value)) {
+                $needle = spl_object_hash($value);
+            } else {
+                $needle = $value;
+            }
+
+            if (! array_key_exists($needle, $seen)) {
+                $seen[$needle] = true;
+                yield $key => $value;
+            }
+        }
+    }
 }

tests/SeqTest.php

@@ -4,6 +4,7 @@
 
 use ArrayIterator;
 use ipl\Stdlib\Seq;
+use stdClass;
 
 class SeqTest extends TestCase
 {
@@ -214,4 +215,82 @@ public function testMapWithKeyedGenerators()
             $result
         );
     }
+
+    public function testUniqueWithArray()
+    {
+        $object1 = new stdClass();
+        $object2 = new stdClass();
+        $arr = [1, 2, 2, 3, '3', $object1, $object1, $object2];
+        $result = iterator_to_array(Seq::unique($arr));
+
+        $this->assertSame(
+            [0 => 1, 1 => 2, 3 => 3, 5 => $object1, 7 => $object2],
+            $result
+        );
+    }
+
+    public function testUniqueWithKeyedArray()
+    {
+        $object1 = new stdClass();
+        $object2 = new stdClass();
+        $arr = ['a' => 1, 'b' => 2, 0 => 2, -1 => 3, 1 => '3', 2 => $object1, 3 => $object1, 4 => $object2];
+        $result = iterator_to_array(Seq::unique($arr));
+
+        $this->assertSame(
+            ['a' => 1, 'b' => 2, -1 => 3, 2 => $object1, 4 => $object2],
+            $result
+        );
+    }
+
+    public function testUniqueWithGenerator()
+    {
+        $object1 = new stdClass();
+        $object2 = new stdClass();
+        $generator = function () use ($object1, $object2) {
+            yield from [1, 2, 2, 3, '3', $object1, $object1, $object2];
+        };
+        $result = iterator_to_array(Seq::unique($generator()));
+
+        $this->assertSame(
+            [0 => 1, 1 => 2, 3 => 3, 5 => $object1, 7 => $object2],
+            $result
+        );
+    }
+
+    public function testUniqueWithKeyedGenerator()
+    {
+        $object1 = new stdClass();
+        $object2 = new stdClass();
+        $generator = function () use ($object1, $object2) {
+            yield from ['a' => 1, 'b' => 2, 0 => 2, -1 => 3, 1 => '3', 2 => $object1, 3 => $object1, 4 => $object2];
+        };
+        $result = iterator_to_array(Seq::unique($generator()));
+
+        $this->assertSame(
+            ['a' => 1, 'b' => 2, -1 => 3, 2 => $object1, 4 => $object2],
+            $result
+        );
+    }
+
+    public function testUniqueWithStringsIsCaseSensitiveByDefault()
+    {
+        $arr = ['foo', 'bar', 'FOO', 'BAR', 'foo'];
+        $result = iterator_to_array(Seq::unique($arr));
+
+        $this->assertSame(
+            [0 => 'foo', 1 => 'bar', 2 => 'FOO', 3 => 'BAR'],
+            $result
+        );
+    }
+
+    public function testUniqueWithStringsCaseInsensitive()
+    {
+        $arr = ['foo', 'bar', 'FOO', 'BAR', 'foo'];
+        $result = iterator_to_array(Seq::unique($arr, false));
+
+        $this->assertSame(
+            [0 => 'foo', 1 => 'bar'],
+            $result
+        );
+    }
 }