Throw exception on invalid pointer

src/Exceptions/PointerException.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Cerbero\JsonParser\Exceptions;
+
+/**
+ * The exception thrown when a pointer-related error occurs.
+ *
+ */
+class PointerException extends JsonParserException
+{
+    /**
+     * Retrieve the exception when the given pointer is invalid
+     *
+     * @param string $pointer
+     * @return static
+     */
+    public static function invalid(string $pointer): static
+    {
+        return new static("The string [$pointer] is not a valid JSON pointer", static::CODE_POINTER_INVALID);
+    }
+}

src/Pointers/Pointer.php

@@ -3,6 +3,7 @@
 namespace Cerbero\JsonParser\Pointers;
 
 use ArrayAccess;
+use Cerbero\JsonParser\Exceptions\PointerException;
 use Cerbero\JsonParser\Tree;
 use Stringable;
 
@@ -44,6 +45,10 @@ class Pointer implements ArrayAccess, Stringable
      */
     protected function toReferenceTokens(): array
     {
+        if (preg_match('#^(?:/(?:(?:[^/~])|(?:~[01]))*)*$#', $this->pointer) === 0) {
+            throw PointerException::invalid($this->pointer);
+        }
+
         $tokens = explode('/', substr($this->pointer, 1));
 
         return array_map(fn (string $token) => str_replace(['~1', '~0'], ['/', '~'], $token), $tokens);

tests/Dataset.php

@@ -59,4 +59,14 @@ class Dataset
             }
         }
     }
+
+    /**
+     * Retrieve the dataset to test invalid pointers
+     *
+     * @return Generator
+     */
+    public static function forInvalidPointers(): Generator
+    {
+        yield from ['abc', '/foo~2', '/~', ' '];
+    }
 }

tests/Feature/PointersTest.php

@@ -1,6 +1,7 @@
 <?php
 
 use Cerbero\JsonParser\Dataset;
+use Cerbero\JsonParser\Exceptions\PointerException;
 use Cerbero\JsonParser\JsonParser;
 
 it('supports single JSON pointers', function (string $json, string $pointer, array $parsed) {
@@ -8,6 +9,12 @@ it('supports single JSON pointers', function (string $json, string $pointer, arr
 })->with(Dataset::forSinglePointers());
 
 
+it('throws an exception when providing an invalid JSON pointer', function (string $pointer) {
+    expect(fn () => iterator_to_array(JsonParser::parse('{}')->pointer($pointer)))
+        ->toThrow(PointerException::class, "The string [$pointer] is not a valid JSON pointer");
+})->with(Dataset::forInvalidPointers());
+
+
 // it('supports multiple JSON pointers', function (string $json, array $pointers, array $parsed) {
 //     expect(JsonParser::parse($json)->pointer(...$pointers))->toParseTo($parsed);
 // })->with(Dataset::forMultiplePointers());