Реализация json_encode

                        
<?php 

/** 

 * Реализация json_encode 

*/ 



if (!function_exists('json_encode')) {   

    function json_encode($value)  

    { 

        if (is_int($value)) { 

            return (string)$value;    

        } elseif (is_string($value)) { 

            $value = str_replace(array('\\', '/', '"', "\r", "\n", "\b", "\f", "\t"),  

                                 array('\\\\', '\/', '\"', '\r', '\n', '\b', '\f', '\t'), $value); 

            $convmap = array(0x80, 0xFFFF, 0, 0xFFFF); 

            $result = ""; 

            for ($i = mb_strlen($value) - 1; $i >= 0; $i--) { 

                $mb_char = mb_substr($value, $i, 1); 

                if (mb_ereg("&#(\\d+);", mb_encode_numericentity($mb_char, $convmap, "UTF-8"), $match)) { 

                    $result = sprintf("\\u%04x", $match[1]) . $result; 

                } else { 

                    $result = $mb_char . $result; 

                } 

            } 

            return '"' . $result . '"';                 

        } elseif (is_float($value)) { 

            return str_replace(",", ".", $value);          

        } elseif (is_null($value)) { 

            return 'null'; 

        } elseif (is_bool($value)) { 

            return $value ? 'true' : 'false'; 

        } elseif (is_array($value)) { 

            $with_keys = false; 

            $n = count($value); 

            for ($i = 0, reset($value); $i < $n; $i++, next($value)) { 

                        if (key($value) !== $i) { 

                  $with_keys = true; 

                  break; 

                        } 

            } 

        } elseif (is_object($value)) { 

            $with_keys = true; 

        } else { 

            return ''; 

        } 

        $result = array(); 

        if ($with_keys) { 

            foreach ($value as $key => $v) { 

                $result[] = json_encode((string)$key) . ':' . json_encode($v);     

            } 

            return '{' . implode(',', $result) . '}';                 

        } else { 

            foreach ($value as $key => $v) { 

                $result[] = json_encode($v);     

            } 

            return '[' . implode(',', $result) . ']'; 

        } 

    }  

}