Update InOrder traverser.

Author: drupol

spec/drupol/phptree/Exporter/GraphSpec.php

@@ -5,7 +5,6 @@
 namespace spec\drupol\phptree\Exporter;
 
 use drupol\phptree\Exporter\Graph;
-use drupol\phptree\Node\Node;
 use drupol\phptree\Node\ValueNode;
 use drupol\phptree\Traverser\BreadthFirst;
 use PhpSpec\ObjectBehavior;
@@ -20,9 +19,9 @@ public function it_is_initializable()
     public function it_can_generate_a_graph()
     {
         $root = new ValueNode('root');
-        $child1 = new Node();
-        $child2 = new Node();
-        $child3 = new Node();
+        $child1 = new ValueNode();
+        $child2 = new ValueNode();
+        $child3 = new ValueNode();
         $root
             ->add($child1, $child2, $child3);
 

spec/drupol/phptree/Exporter/SimpleArraySpec.php

@@ -25,7 +25,7 @@ public function it_can_export_to_an_array()
 
         $nodes = [];
         foreach (\range('A', 'J') as $value) {
-            $nodes[$value] = new ValueNode($value);
+            $nodes[$value] = new ValueNode($value, 2);
         }
 
         $tree->add(...\array_values($nodes));

spec/drupol/phptree/Exporter/TextSpec.php

@@ -25,7 +25,7 @@ public function it_can_export_to_text()
 
         $nodes = [];
         foreach (\range('A', 'J') as $value) {
-            $nodes[$value] = new ValueNode($value);
+            $nodes[$value] = new ValueNode($value, 2);
         }
 
         $tree->add(...\array_values($nodes));

spec/drupol/phptree/Node/NodeSpec.php

@@ -237,7 +237,7 @@ public function it_can_get_its_depth()
 
         $nodes = [];
         foreach (\range('A', 'Z') as $v) {
-            $nodes[] = new \drupol\phptree\Node\ValueNode($v);
+            $nodes[] = new \drupol\phptree\Node\ValueNode($v, 2);
         }
 
         $tree->add(...$nodes);

spec/drupol/phptree/Traverser/InOrderSpec.php

@@ -15,7 +15,7 @@ public function it_is_initializable()
         $this->shouldHaveType(InOrder::class);
     }
 
-    public function it_can_traverse_a_tree()
+    public function it_can_traverse_a_tree_of_degree2()
     {
         $tree = new ValueNode('root', 2);
 
@@ -39,4 +39,50 @@ public function it_can_traverse_a_tree()
             ->traverse($tree)
             ->shouldYield(new \ArrayIterator($nodes));
     }
+
+    public function it_can_traverse_a_tree_of_degree4()
+    {
+        $tree = new ValueNode('root', 4);
+
+        foreach (\range('A', 'Z') as $key => $value) {
+            $nodes[$value] = new ValueNode($value, 4);
+        }
+
+        $tree->add(...\array_values($nodes));
+
+        $nodes['root'] = $tree;
+        $nodes = [
+            $nodes['U'],
+            $nodes['V'],
+            $nodes['E'],
+            $nodes['W'],
+            $nodes['X'],
+            $nodes['Y'],
+            $nodes['F'],
+            $nodes['Z'],
+            $nodes['A'],
+            $nodes['G'],
+            $nodes['H'],
+            $nodes['I'],
+            $nodes['J'],
+            $nodes['B'],
+            $nodes['K'],
+            $nodes['L'],
+            $nodes['root'],
+            $nodes['M'],
+            $nodes['N'],
+            $nodes['C'],
+            $nodes['O'],
+            $nodes['P'],
+            $nodes['Q'],
+            $nodes['R'],
+            $nodes['D'],
+            $nodes['S'],
+            $nodes['T'],
+        ];
+
+        $this
+            ->traverse($tree)
+            ->shouldYield(new \ArrayIterator($nodes));
+    }
 }

src/Node/NaryNode.php

@@ -61,6 +61,7 @@ public function capacity(): int
     public function add(NodeInterface ...$nodes): NodeInterface
     {
         foreach ($nodes as $node) {
+            /** @var \drupol\phptree\Node\Node $parent */
             $parent = $this->findFirstAvailableNode();
             $parent->storage['children'][] = $node->setParent($parent);
         }
@@ -83,8 +84,14 @@ public function getTraverser()
      */
     private function findFirstAvailableNode(): NodeInterface
     {
+        $capacity = $this->capacity();
+
         foreach ($this->getTraverser()->traverse($this) as $node) {
-            if ($node->degree() >= $node->capacity()) {
+            if (\method_exists($node, 'capacity')) {
+                $capacity = $node->capacity();
+            }
+
+            if ($node->degree() >= $capacity) {
                 continue;
             }
 

src/Traverser/InOrder.php

@@ -31,8 +31,11 @@ public function traverse(NodeInterface $node): \Traversable
      */
     private function doTraverse(NodeInterface $node): \Traversable
     {
-        foreach ($node->children() as $child) {
-            if ($node->lastChild() === $child) {
+        $countChildren = $node->degree();
+        $middle = \floor($countChildren/2);
+
+        foreach ($node->children() as $key => $child) {
+            if ((int) $key === (int) $middle) {
                 yield $this->index => $node;
                 $this->index++;
             }