Fix issue with TrieNode when value is ending with same string.

Author: drupol

spec/drupol/phptree/Node/TrieNodeSpec.php

@@ -20,6 +20,12 @@ public function it_can_add_node()
         $this->beConstructedWith('root', 'root');
 
         $nodes = [
+            1000,
+            1001,
+            10011,
+            2000,
+            2001,
+            20011,
             'ab',
             'abc',
             'abcd',
@@ -31,12 +37,12 @@ public function it_can_add_node()
         ];
 
         foreach ($nodes as $key => $value) {
-            $nodes[$key] = new KeyValueNode($key, $value);
+            $nodes[$key] = new KeyValueNode($key, (string) $value);
         }
 
         $this
             ->add(...$nodes)
             ->count()
-            ->shouldReturn(25);
+            ->shouldReturn(43);
     }
 }

src/Node/TrieNode.php

@@ -23,7 +23,7 @@ public function add(NodeInterface ...$nodes): NodeInterface
             $parent = $this->append($node);
 
             $dataWithoutFirstLetter = \substr($data, 1);
-            if (!empty($dataWithoutFirstLetter)) {
+            if ($dataWithoutFirstLetter > '') {
                 $parent->add(new TrieNode($hash, $dataWithoutFirstLetter));
             } else {
                 $nodes = [$node->getValue()];