[PHP 8.5] Add array_first and array_last

Adds polyfills for the PHP 8.5's `array_first` and `array_last`
functions.

The polyfills would have been a bit cleaner if we used the
`array_key_first` and `array_key_last` functions, but they were added
in PHP 7.3, and are not available on PHP 7.2.

This adds the same tests from php-src patch.

 - [RFC: `array_first()` and `array_last()`](https://wiki.php.net/rfc/array_first_last)
 - [php-src commit](php/php-src@168343d)
 - [PHP.Watch polyfill for PHP 8.0+](https://php.watch/versions/8.5/array_first-array_last)

Co-authored-by: Nicolas Grekas <nicolas.grekas@gmail.com>

Author: Ayesh

README.md

@@ -74,6 +74,7 @@ Polyfills are provided for:
 - the `CURL_HTTP_VERSION_3` and `CURL_HTTP_VERSION_3ONLY` constants introduced in PHP 8.4;
 - the `get_error_handler` and `get_exception_handler` functions introduced in PHP 8.5;
 - the `NoDiscard` attribute introduced in PHP 8.5;
+- the `array_first` and `array_last` functions introduced in PHP 8.5;
 
 It is strongly recommended to upgrade your PHP version and/or install the missing
 extensions whenever possible. This polyfill should be used only when there is no

src/Php85/Php85.php

@@ -33,4 +33,18 @@ public static function get_exception_handler(): ?callable
 
         return $handler;
     }
+
+    public static function array_first(array $array)
+    {
+        foreach ($array as $value) {
+            return $value;
+        }
+
+        return null;
+    }
+
+    public static function array_last(array $array)
+    {
+        return $array ? current(array_slice($array, -1)) : null;
+    }
 }

src/Php85/README.md

@@ -5,6 +5,7 @@ This component provides features added to PHP 8.5 core:
 
 - [`get_error_handler` and `get_exception_handler`](https://wiki.php.net/rfc/get-error-exception-handler)
 - [`NoDiscard`](https://wiki.php.net/rfc/marking_return_value_as_important)
+- [`array_first` and `array_last`](https://wiki.php.net/rfc/array_first_last)
 
 More information can be found in the
 [main Polyfill README](https://github.com/symfony/polyfill/blob/main/README.md).

src/Php85/bootstrap.php

@@ -22,3 +22,11 @@ function get_error_handler(): ?callable { return p\Php85::get_error_handler(); }
 if (!function_exists('get_exception_handler')) {
     function get_exception_handler(): ?callable { return p\Php85::get_exception_handler(); }
 }
+
+if (!function_exists('array_first')) {
+    function array_first(array $array) { return p\Php85::array_first($array); }
+}
+
+if (!function_exists('array_last')) {
+    function array_last(array $array) { return p\Php85::array_last($array); }
+}

tests/Php85/Php85Test.php

@@ -78,6 +78,44 @@ public static function provideHandler()
         $handler = new TestHandlerInvokable();
         yield [$handler, $handler];
     }
+
+    public function testArrayFirstArrayLast()
+    {
+        $this->assertNull(array_first([]));
+        $this->assertNull(array_last([]));
+
+        $array = [1, 2, 3];
+        unset($array[0], $array[1], $array[2]);
+
+        $this->assertNull(array_first([]));
+        $this->assertNull(array_last([]));
+
+
+        $this->assertSame("single element", array_first(["single element"]));
+        $this->assertSame("single element", array_last(["single element"]));
+
+        $str = "hello world";
+        $this->assertSame($str, array_first([&$str, 1]));
+        $this->assertSame(1, array_last([&$str, 1]));
+
+        $this->assertSame(1, array_first([1, &$str]));
+        $this->assertSame($str, array_last([1, &$str]));
+
+        $this->assertSame(1, array_first([1 => 1, 0 => 0, 3 => 3, 2 => 2]));
+        $this->assertSame(2, array_last([1 => 1, 0 => 0, 3 => 3, 2 => 2]));
+
+        $this->assertSame('a1', array_first(['a' => 'a1', 'b' => 'b1', 'c' => 'c1']));
+        $this->assertSame('c1', array_last(['a' => 'a1', 'b' => 'b1', 'c' => 'c1']));
+
+        $this->assertSame([], array_first([100 => []]));
+        $this->assertSame([], array_last([100 => []]));
+
+        $this->assertEquals(new \stdClass(), array_first([new \stdClass, false]));
+        $this->assertFalse(array_last([new \stdClass, false]));
+
+        $this->assertTrue(array_first([true, new \stdClass]));
+        $this->assertEquals(new \stdClass(), array_last([true, new \stdClass]));
+    }
 }
 
 class TestHandler