From 3c90eb9a0740ddfa4c9efad45d2f9769bd34ba37 Mon Sep 17 00:00:00 2001
From: Sasha <alex@aevent.com>
Date: Fri, 17 Jul 2026 07:32:02 -0700
Subject: [PATCH] PathException with "The path does not apply to this data!"
 for objects like {"+1": ...} because filter_var('+1', FILTER_VALIDATE_INT) is
 1.

---
 src/JsonPointer.php           | 10 ++++++++++
 tests/src/AssociativeTest.php | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/JsonPointer.php b/src/JsonPointer.php
index 1311ad3..6d080aa 100644
--- a/src/JsonPointer.php
+++ b/src/JsonPointer.php
@@ -120,6 +120,16 @@ public static function add(&$holder, $pathItems, $value, $flags = self::RECURSIV
                 }
             } else { // null or array
                 $intKey = filter_var($key, FILTER_VALIDATE_INT);
+
+                // Avoid PathException with objects like {"+1": ...}
+                $hasPlus = $intKey !== false &&
+                    is_string($key) &&
+                    $key !== '' &&
+                    $key[0] === '+';
+                if ($hasPlus) {
+                    $intKey = false;
+                }
+
                 if ($ref === null && (false === $intKey || $intKey !== 0)) {
                     $key = (string)$key;
                     if ($flags & self::RECURSIVE_KEY_CREATION) {
diff --git a/tests/src/AssociativeTest.php b/tests/src/AssociativeTest.php
index d3a7cb6..0771676 100644
--- a/tests/src/AssociativeTest.php
+++ b/tests/src/AssociativeTest.php
@@ -59,4 +59,34 @@ public function testDiffAssociative()
         $patch->apply($original);
         $this->assertEquals($newJson, $original);
     }
-}
\ No newline at end of file
+
+    /**
+     * Avoid PathException with objects like {"+1": ...}
+     *
+     * @throws \Swaggest\JsonDiff\Exception
+     */
+    public function testSignedIntegerLikeKey()
+    {
+        $original = [
+            '+1' => [
+                ['name' => 'first', 'keep' => 1],
+                ['name' => 'second', 'keep' => 2],
+            ],
+            '-1' => [
+                ['name' => 'other', 'keep' => 3],
+            ],
+        ];
+
+        $patch = JsonPatch::import([
+            ['op' => 'replace', 'path' => '/+1/1/name', 'value' => 'patched'],
+            ['op' => 'replace', 'path' => '/-1/0/name', 'value' => 'negative'],
+        ]);
+        $patch->setFlags(JsonPatch::TOLERATE_ASSOCIATIVE_ARRAYS);
+        $patch->apply($original);
+
+        $this->assertSame('patched', $original['+1'][1]['name']);
+        $this->assertSame('negative', $original['-1'][0]['name']);
+        $this->assertSame('first', $original['+1'][0]['name']);
+        $this->assertArrayNotHasKey(1, $original);
+    }
+}