[13.x] Remove function existence checks (#54876)

* Remove function existence checks

* remove unused JsonException import

---------

Co-authored-by: Xurshudyan <[email protected]>

Author: xurshudyan

src/Illuminate/Support/Str.php

@@ -4,7 +4,6 @@
 
 use Closure;
 use Illuminate\Support\Traits\Macroable;
-use JsonException;
 use League\CommonMark\Environment\Environment;
 use League\CommonMark\Extension\GithubFlavoredMarkdownExtension;
 use League\CommonMark\Extension\InlinesOnly\InlinesOnlyExtension;
@@ -546,17 +545,7 @@ public static function isJson($value)
             return false;
         }
 
-        if (function_exists('json_validate')) {
-            return json_validate($value, 512);
-        }
-
-        try {
-            json_decode($value, true, 512, JSON_THROW_ON_ERROR);
-        } catch (JsonException) {
-            return false;
-        }
-
-        return true;
+        return json_validate($value, 512);
     }
 
     /**
@@ -906,17 +895,7 @@ public static function numbers($value)
      */
     public static function padBoth($value, $length, $pad = ' ')
     {
-        if (function_exists('mb_str_pad')) {
-            return mb_str_pad($value, $length, $pad, STR_PAD_BOTH);
-        }
-
-        $short = max(0, $length - mb_strlen($value));
-        $shortLeft = floor($short / 2);
-        $shortRight = ceil($short / 2);
-
-        return mb_substr(str_repeat($pad, $shortLeft), 0, $shortLeft).
-               $value.
-               mb_substr(str_repeat($pad, $shortRight), 0, $shortRight);
+        return mb_str_pad($value, $length, $pad, STR_PAD_BOTH);
     }
 
     /**
@@ -929,13 +908,7 @@ public static function padBoth($value, $length, $pad = ' ')
      */
     public static function padLeft($value, $length, $pad = ' ')
     {
-        if (function_exists('mb_str_pad')) {
-            return mb_str_pad($value, $length, $pad, STR_PAD_LEFT);
-        }
-
-        $short = max(0, $length - mb_strlen($value));
-
-        return mb_substr(str_repeat($pad, $short), 0, $short).$value;
+        return mb_str_pad($value, $length, $pad, STR_PAD_LEFT);
     }
 
     /**
@@ -948,13 +921,7 @@ public static function padLeft($value, $length, $pad = ' ')
      */
     public static function padRight($value, $length, $pad = ' ')
     {
-        if (function_exists('mb_str_pad')) {
-            return mb_str_pad($value, $length, $pad, STR_PAD_RIGHT);
-        }
-
-        $short = max(0, $length - mb_strlen($value));
-
-        return $value.mb_substr(str_repeat($pad, $short), 0, $short);
+        return mb_str_pad($value, $length, $pad, STR_PAD_RIGHT);
     }
 
     /**

src/Illuminate/Validation/Concerns/ValidatesAttributes.php

@@ -1526,13 +1526,7 @@ public function validateJson($attribute, $value)
             return false;
         }
 
-        if (function_exists('json_validate')) {
-            return json_validate($value);
-        }
-
-        json_decode($value);
-
-        return json_last_error() === JSON_ERROR_NONE;
+        return json_validate($value);
     }
 
     /**