tree reindexing & sorting

readme.md

@@ -608,4 +608,4 @@ composer test
 
 Ideas or contribution is welcome. Please send a PR or submit an issue.
 
-And if you happen to like the library, spread the word 🙏.
+And if you happen to like the library, give it a star and spread the word 🙏.

src/Seed.php

@@ -95,10 +95,19 @@ public static function attr(string|int $name, mixed $default = null): callable
 
     /**
      * Accepts any iterable and returns an iterator.
-     * Useful where en iterator is required, but any iterable or array is provided.
+     * Useful where an iterator is required, but an iterable type is provided.
      */
     public static function iterator(iterable $input): Iterator
     {
         return is_array($input) ? new ArrayIterator($input) : new IteratorIterator($input);
     }
+
+    /**
+     * Accepts any iterable and returns an array.
+     * Useful where an array is required, but an iterable type is provided.
+     */
+    public static function array(iterable $input): array
+    {
+        return is_array($input) ? $input : iterator_to_array($input);
+    }
 }

src/Tree.php

@@ -9,7 +9,7 @@
 /**
  * A helper class for high-level tree operations.
  *
- * This contrasts with the low-level interface.
+ * This contrasts with the low-level interface of movable nodes:
  * @see MovableNodeContract
  *
  * @author Andrej Rypak <[email protected]>
@@ -115,6 +115,35 @@ public static function unlinkChildren(
         $parent->removeChildren();
     }
 
+    /**
+     *
+     * Usage of <=> (spaceship) operator to compare based on path props:
+     * fn(Node $a, Node $b) => $a->data()->path <=> $b->data()->path
+     *
+     */
+    public static function reindexTree(
+        MovableNodeContract $node,
+        ?callable $key,
+        ?callable $sort,
+    ): void {
+        $children = Seed::array($node->children());
+        $node->removeChildren();
+        if (null !== $sort) {
+            uasort($children, $sort);
+        }
+        $seq = 0;
+        foreach ($children as $childKey => $child) {
+            if (!$child instanceof MovableNodeContract) {
+                // TODO improve exceptions
+                throw new Exception('Child not movable.');
+            }
+            $newKey = null !== $key ? $key($child, $childKey, $seq) : $childKey;
+            $node->addChild($child, $newKey);
+            self::reindexTree($child, $key, $sort);
+            $seq += 1;
+        }
+    }
+
     /**
      * @internal
      */