do not modify data on failing add

Author: vearutop

src/JsonPointer.php

@@ -75,7 +75,15 @@ public static function add(&$holder, $pathItems, $value, $recursively = true)
                         Exception::EMPTY_PROPERTY_NAME_UNSUPPORTED);
                 }
 
-                $ref = &$ref->$key;
+                if ($recursively) {
+                    $ref = &$ref->$key;
+                } else {
+                    if (!isset($ref->$key) && count($pathItems)) {
+                        throw new Exception('Non-existent path item: ' . $key);
+                    } else {
+                        $ref = &$ref->$key;
+                    }
+                }
             } else { // null or array
                 $intKey = filter_var($key, FILTER_VALIDATE_INT);
                 if ($ref === null && (false === $intKey || $intKey !== 0)) {

tests/src/JsonPatchTest.php

@@ -123,4 +123,23 @@ public function testApplyContinueOnError()
         $this->assertSame('Key not found: missing2', $errors[1]->getMessage());
     }
 
+
+    public function testApplyNonExistentLevelTwo()
+    {
+        $data = new \stdClass();
+        $p = new JsonPatch();
+        $p->op(new JsonPatch\Add('/some/path', 22));
+        $p->apply($data, false);
+        $this->assertEquals(new \stdClass(), $data);
+    }
+
+    public function testApplyNonExistentLevelOne()
+    {
+        $data = new \stdClass();
+        $p = new JsonPatch();
+        $p->op(new JsonPatch\Add('/some', 22));
+        $p->apply($data);
+        $this->assertEquals((object)array('some' => 22), $data);
+    }
+
 }