Improve performance.

benchmarks/AbstractBench.php

@@ -11,6 +11,6 @@ abstract class AbstractBench
      */
     public function getData()
     {
-        return \range(1, 100);
+        return \range(1, 1000);
     }
 }

spec/drupol/phptree/Node/NodeSpec.php

@@ -34,12 +34,12 @@ public function it_can_remove()
         $this
             ->remove($node2);
 
-        $this->children()[0]->shouldReturn($node1);
-
         $this
             ->remove($node1);
 
-        $this->children()->shouldReturn([]);
+        $this
+            ->count()
+            ->shouldReturn(0);
     }
 
     public function it_can_get_the_size()
@@ -83,15 +83,19 @@ public function it_can_get_its_children()
     {
         $this
             ->children()
-            ->shouldReturn([]);
+            ->shouldBeAnInstanceOf(\Generator::class);
+
+        $this
+            ->children()
+            ->shouldYield(new \ArrayIterator([]));
 
         $node = new Node();
 
         $this
             ->add($node)
             ->add($node)
             ->children()
-            ->shouldReturn([$node, $node]);
+            ->shouldYield(new \ArrayIterator([$node, $node]));
     }
 
     public function it_can_get_the_last_children()
@@ -209,12 +213,12 @@ public function it_can_use_withChildren()
         $this
             ->withChildren($child)
             ->children()
-            ->shouldReturn([$child]);
+            ->shouldYield(new \ArrayIterator([$child]));
 
         $this
             ->withChildren()
             ->children()
-            ->shouldReturn([]);
+            ->shouldYield(new \ArrayIterator([]));
     }
 
     public function it_can_get_its_depth()

spec/drupol/phptree/Node/ValueNodeSpec.php

@@ -13,7 +13,7 @@ public function it_is_initializable()
     {
         $this->shouldHaveType(ValueNode::class);
 
-        $this->children()->shouldReturn([]);
+        $this->children()->shouldYield(new \ArrayIterator([]));
     }
 
     public function it_can_be_set_with_a_value()

src/Node/Node.php

@@ -77,9 +77,9 @@ public function getParent(): ?NodeInterface
     /**
      * {@inheritdoc}
      */
-    public function children(): array
+    public function children(): \Traversable
     {
-        return $this->storage['children'];
+        yield from new \ArrayIterator($this->storage['children']);
     }
 
     /**
@@ -109,32 +109,33 @@ public function getAncestors(): \Traversable
      */
     public function isLeaf(): bool
     {
-        return [] === $this->children();
+        return [] === $this->storage['children'];
     }
 
     /**
      * {@inheritdoc}
      */
     public function isRoot(): bool
     {
-        return null === $this->getParent();
+        return null === $this->storage['parent'];
     }
 
     /**
      * {@inheritdoc}
      */
     public function getSibblings(): \Traversable
     {
-        $parent = $this->getParent();
+        $parent = $this->storage['parent'];
 
         if (null === $parent) {
-            return [];
+            return new \ArrayIterator([]);
         }
 
         foreach ($parent->children() as $child) {
             if ($child === $this) {
                 continue;
             }
+
             yield $child;
         }
     }
@@ -152,13 +153,14 @@ public function degree(): int
      */
     public function count(): int
     {
-        return \array_reduce(
-            $this->children(),
-            function ($carry, $node) {
-                return 1 + $carry + $node->count();
-            },
-            0
-        );
+        $count = 0;
+
+        /** @var \drupol\phptree\Node\NodeInterface $child */
+        foreach ($this->children() as $child) {
+            $count += 1 + $child->count();
+        }
+
+        return $count;
     }
 
     /**

src/Node/NodeInterface.php

@@ -53,21 +53,21 @@ public function remove(NodeInterface ...$node): NodeInterface;
     /**
      * Get the children.
      *
-     * @return \drupol\phptree\Node\NodeInterface[]
+     * @return \Traversable<\drupol\phptree\Node\NodeInterface>
      *   The children.
      */
-    public function children(): array;
+    public function children(): \Traversable;
 
     /**
-     * Check if the node is a leaf.
+     * Check if the node has children, then it's a leaf.
      *
      * @return bool
-     *   True if it's a leaf, false otherwise.
+     *   True if it has children, false otherwise.
      */
     public function isLeaf(): bool;
 
     /**
-     * Check if the node is the root node.
+     * Check if the node is the root node (Node parent is null)
      *
      * @return bool
      *   True if it's a root node, false otherwise.
@@ -78,20 +78,20 @@ public function isRoot(): bool;
      * Get the ancestors of a node.
      *
      * @return \Traversable
-     *   The array of ancestors.
+     *   The ancestors.
      */
     public function getAncestors(): \Traversable;
 
     /**
      * Get the node's sibblings.
      *
      * @return \Traversable
-     *   The array of sibblings.
+     *   The sibblings.
      */
     public function getSibblings(): \Traversable;
 
     /**
-     * The number of children a node has.
+     * The amount of children a node has.
      *
      * @return int
      *   The amount of children.
@@ -107,7 +107,7 @@ public function degree(): int;
     public function depth(): int;
 
     /**
-     * Get a clone of the object without any children.
+     * Get a clone of the object with or without children.
      *
      * @param \drupol\phptree\Node\NodeInterface ...$nodes
      *   The children that the clone will have.