Add function to get next strpos of any of a specified set of needles

tests/MD_STD_Test.php

@@ -706,4 +706,41 @@ final class MD_STD_Test extends TestCase {
         self::assertEquals("en", MD_STD::get_user_lang_no_cookie(["de", "en"], "en"));
 
     }
+
+    /**
+     * Data provider for returning a tmp file.
+     *
+     * @return array<string, array{0: non-empty-string, 1: non-empty-array<non-empty-string>, 2: int}>
+     */
+    public static function strpos_multi_provider():array {
+
+        return [
+            "Search quotation markes on when='" => ["when='", ['"', '\''], 5],
+            "Search quotation markes on when=\"" => ["when=\"", ['"', '\''], 5],
+            "Search quotation markes on when=\"'" => ["when=\"'", ['"', '\''], 5],
+            "Search quotation markes on when= (non-existent)" => ["when=", ['"', '\''], -1],
+        ];
+
+    }
+
+    /**
+     * Checks unlink_if_exists works.
+     *
+     * @param non-empty-string                  $haystack Haystack.
+     * @param non-empty-array<non-empty-string> $needles  Needles.
+     * @param integer                           $expected Expected position.
+     *
+     * @return void
+     */
+    #[DataProvider('strpos_multi_provider')]
+    public function test_strpos_multi(string $haystack, array $needles, int $expected):void {
+
+        if ($expected === -1) {
+            self::assertEmpty(MD_STD::strpos_multi($haystack, $needles));
+        }
+        else {
+            self::assertEquals($expected, MD_STD::strpos_multi($haystack, $needles)['position']);
+        }
+
+    }
 }