Add new Filter modifier.

Author: drupol

spec/loophp/phptree/Modifier/FilterSpec.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace spec\loophp\phptree\Modifier;
+
+use loophp\phptree\Modifier\Filter;
+use loophp\phptree\Node\ValueNode;
+use loophp\phptree\Node\ValueNodeInterface;
+use PhpSpec\ObjectBehavior;
+
+class FilterSpec extends ObjectBehavior
+{
+    public function it_can_filter_a_tree_with_a_callback()
+    {
+        $tree = new ValueNode('root', 10);
+
+        $nodes = [];
+
+        foreach (range(1, 11) as $value) {
+            $nodes[] = new ValueNode($value);
+        }
+        $tree->add(...$nodes);
+
+        $this
+            ->modify($tree)
+            ->count()
+            ->shouldReturn(6);
+    }
+
+    public function it_is_initializable()
+    {
+        $this->shouldHaveType(Filter::class);
+    }
+
+    public function let()
+    {
+        $this->beConstructedWith(
+            static function (ValueNodeInterface $node) {
+                return 0 === ($node->getValue() % 2);
+            }
+        );
+    }
+}

src/Modifier/Filter.php

@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\phptree\Modifier;
+
+use loophp\phptree\Node\NodeInterface;
+
+/**
+ * Class Filter.
+ */
+class Filter implements ModifierInterface
+{
+    /**
+     * @var callable
+     */
+    private $filter;
+
+    /**
+     * Filter constructor.
+     *
+     * @param callable $filter
+     */
+    public function __construct(callable $filter)
+    {
+        $this->filter = $filter;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function modify(NodeInterface $tree): NodeInterface
+    {
+        /** @var \loophp\phptree\Node\MerkleNode $item */
+        foreach ($tree->all() as $item) {
+            if (null === $parent = $item->getParent()) {
+                continue;
+            }
+
+            if (false === (bool) ($this->filter)($item)) {
+                continue;
+            }
+
+            $parent->remove($item);
+            $this->modify($parent);
+        }
+
+        return $tree;
+    }
+}