php json decode implement

For users of php 5.1.6 or lower.

FastJSON.class.php

 
<?php
/**_______________________________________
 *
 *  FastJSON (strict version for PHP 5.2 or greater),
 *  simple and fast Pear Service_JSON encoder/decoder alternative
 *  [http://pear.php.net/pepr/pepr-proposal-show.php?id=198]
 * ---------------------------------------
 * This class is about two time faster than Pear Service_JSON class.
 * This class is probably not powerful as Service_JSON but it has
 * no dependencies and converts correctly ASCII range 0x00 - 0x1F too.
 * There's any string convertion, just regular RFC specific characters are converted
 * into \u00XX string.
 * To don't have problems with other chars try to use utf8_encode($json_encoded_string).
 * To recieve correctly JSON strings from JavaScript use encodeURIComponent then
 * use, if is necessary, utef8_decode before JS to PHP convertion.
 * decode method doesn't returns a standard object class but You can
 * create the corret class directly with FastJSON::convert method
 * and with them You can manage JS Date objects too.
 * ---------------------------------------
 * Summary of static public methods
 *
 *  convert
 *          extra, special method
 *
 *  decode
 *          converts a valid JSON string
 *          into a native PHP variable
 *
 *  encode
 *          converts a native php variable
 *          into a valid JSON string
 * ---------------------------------------
 *
 * Special FastJSON::convert method Informations
 * _______________________________________
 * ---------------------------------------
 * This method is used by FastJSON::encode method but should be used
 * to do these convertions too:
 *
 * - JSON string to time() integer:
 *
 *      FastJSON::convert(decodedDate:String):time()
 *
 *  If You recieve a date string rappresentation You
 *  could convert into respective time() integer.
 *  Example:
 *      FastJSON::convert(FastJSON::decode($clienttime));
 *      // i.e. $clienttime = 2006-11-09T14:42:30
 *      // returned time will be an integer useful with gmdate or date
 *      // to create, for example, this string
 *          // Thu Nov 09 2006 14:42:30 GMT+0100 (Rome, Europe)
 *
 * - time() to JSON string:
 *
 *      FastJSON::convert(time():Int32, true:Boolean):JSON Date String format
 *
 *  You could send server time() informations and send them to clients.
 *  Example:
 *      FastJSON::convert(time(), true);
 *      // i.e. 2006-11-09T14:42:30
 *
 * - associative array to generic class:
 *
 *      FastJSON::convert(array(params=>values), new GenericClass):new Instance of GenericClass
 *
 *  With a decoded JSON object You could convert them
 *  into a new instance of your Generic Class.
 *  Example:
 *      class MyClass {
 *          var $param = "somevalue";
 *          function MyClass($somevar) {
 *              $this->somevar = $somevar;
 *          };
 *          function getVar = function(){
 *              return $this->somevar;
 *          };
 *      };
 *
 *      $instance = new MyClass("example");
 *      $encoded = FastJSON::encode($instance);
 *      // {"param":"somevalue"}
 *
 *      $decoded = FastJSON::decode($encoded);
 *      // $decoded instanceof Object   => true
 *      // $decoded instanceof MyClass  => false
 *
 *      $decoded = FastJSON::convert($decoded, new MyClass("example"));
 *      // $decoded instanceof Object   => true
 *      // $decoded instanceof MyClass  => true
 *
 *      $decoded->getVar(); // example
 *
 * ---------------------------------------
 *
 * @author      Andrea Giammarchi
 * @site        http://www.devpro.it/
 * @version     0.4 [fixed string convertion problems, add stdClass optional convertion instead of associative array (used by default)]
 * @requires    anything
 * @compatibility   PHP >= 5
 * @license
 * ---------------------------------------
 *
 * Copyright (c) 2006 - 2007 Andrea Giammarchi
 *
 * Permission is hereby granted, free of charge,
 * to any person obtaining a copy of this software and associated
 * documentation files (the "Software"),
 * to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * _______________________________________
 */
class FastJSON {

    // public methods

    /**
     * public static method
     *
     *  FastJSON::convert(params:* [, result:Instance]):*
     *
     * @param   *   String or Object
     * @param   Instance    optional new generic class instance if first
     *              parameter is an object.
     * @return  *   time() value or new Instance with object parameters.
     *
     * @note    please read Special FastJSON::convert method Informations
     */
    static public function convert($params, $result = null){
        switch(gettype($params)){
            case    'array':
                    $tmp = array();
                    foreach($params as $key => $value) {
                        if(($value = FastJSON::encode($value)) !== '')
                            array_push($tmp, FastJSON::encode(strval($key)).':'.$value);
                    };
                    $result = '{'.implode(',', $tmp).'}';
                    break;
            case    'boolean':
                    $result = $params ? 'true' : 'false';
                    break;
            case    'double':
            case    'float':
            case    'integer':
                    $result = $result !== null ? strftime('%Y-%m-%dT%H:%M:%S', $params) : strval($params);
                    break;
            case    'NULL':
                    $result = 'null';
                    break;
            case    'string':
                    $i = create_function('&$e, $p, $l', 'return intval(substr($e, $p, $l));');
                    if(preg_match('/^[0-9]{4}\-[0-9]{2}\-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}$/', $params))
                        $result = mktime($i($params, 11, 2), $i($params, 14, 2), $i($params, 17, 2), $i($params, 5, 2), $i($params, 9, 2), $i($params, 0, 4));
                    break;
            case    'object':
                    $tmp = array();
                    if(is_object($result)) {
                        foreach($params as $key => $value)
                            $result->$key = $value;
                    } else {
                        $result = get_object_vars($params);
                        foreach($result as $key => $value) {
                            if(($value = FastJSON::encode($value)) !== '')
                                array_push($tmp, FastJSON::encode($key).':'.$value);
                        };
                        $result = '{'.implode(',', $tmp).'}';
                    }
                    break;
        }
        return $result;
    }

    /**
     * public method
     *
     *  FastJSON::decode(params:String[, useStdClass:Boolean]):*
     *
     * @param   String  valid JSON encoded string
     * @param   Bolean  uses stdClass instead of associative array if params contains objects (default false)
     * @return  *   converted variable or null
     *              is params is not a JSON compatible string.
     * @note    This method works in an optimist way. If JSON string is not valid
     *      the code execution will die using exit.
     *      This is probably not so good but JSON is often used combined with
     *      XMLHttpRequest then I suppose that's better more protection than
     *      just some WARNING.
     *      With every kind of valid JSON string the old error_reporting level
     *      and the old error_handler will be restored.
     *
     * @example
     *      FastJSON::decode('{"param":"value"}'); // associative array
     *      FastJSON::decode('{"param":"value"}', true); // stdClass
     *      FastJSON::decode('["one",two,true,false,null,{},[1,2]]'); // array
     */
    static public function decode($encode, $stdClass = false){
        $pos = 0;
        $slen = is_string($encode) ? strlen($encode) : null;
        if($slen !== null) {
            $error = error_reporting(0);
            set_error_handler(array('FastJSON', '__exit'));
            $result = FastJSON::__decode($encode, $pos, $slen, $stdClass);
            error_reporting($error);
            restore_error_handler();
        }
        else
            $result = null;
        return $result;
    }

    /**
     * public method
     *
     *  FastJSON::encode(params:*):String
     *
     * @param   *       Array, Boolean, Float, Int, Object, String or NULL variable.
     * @return  String      JSON genric object rappresentation
     *              or empty string if param is not compatible.
     *
     * @example
     *      FastJSON::encode(array(1,"two")); // '[1,"two"]'
     *
     *      $obj = new MyClass();
     *      obj->param = "value";
     *      obj->param2 = "value2";
     *      FastJSON::encode(obj); // '{"param":"value","param2":"value2"}'
     */
    static public function encode($decode){
        $result = '';
        switch(gettype($decode)){
            case    'array':
                    if(!count($decode) || array_keys($decode) === range(0, count($decode) - 1)) {
                        $keys = array();
                        foreach($decode as $value) {
                            if(($value = FastJSON::encode($value)) !== '')
                                array_push($keys, $value);
                        }
                        $result = '['.implode(',', $keys).']';
                    }
                    else
                        $result = FastJSON::convert($decode);
                    break;
            case    'string':
                    $replacement = FastJSON::__getStaticReplacement();
                    $result = '"'.str_replace($replacement['find'], $replacement['replace'], $decode).'"';
                    break;
            default:
                    if(!is_callable($decode))
                        $result = FastJSON::convert($decode);
                    break;
        }
        return $result;
    }

    // private methods, uncommented, sorry
    static private function __getStaticReplacement(){
        static $replacement = array('find'=>array(), 'replace'=>array());
        if($replacement['find'] == array()) {
            foreach(array_merge(range(0, 7), array(11), range(14, 31)) as $v) {
                $replacement['find'][] = chr($v);
                $replacement['replace'][] = "\\u00".sprintf("%02x", $v);
            }
            $replacement['find'] = array_merge(array(chr(0x5c), chr(0x2F), chr(0x22), chr(0x0d), chr(0x0c), chr(0x0a), chr(0x09), chr(0x08)), $replacement['find']);
            $replacement['replace'] = array_merge(array('\\\\', '\\/', '\\"', '\r', '\f', '\n', '\t', '\b'), $replacement['replace']);
        }
        return $replacement;
    }
    static private function __decode(&$encode, &$pos, &$slen, &$stdClass){
        switch($encode{$pos}) {
            case 't':
                $result = true;
                $pos += 4;
                break;
            case 'f':
                $result = false;
                $pos += 5;
                break;
            case 'n':
                $result = null;
                $pos += 4;
                break;
            case '[':
                $result = array();
                ++$pos;
                while($encode{$pos} !== ']') {
                    array_push($result, FastJSON::__decode($encode, $pos, $slen, $stdClass));
                    if($encode{$pos} === ',')
                        ++$pos;
                }
                ++$pos;
                break;
            case '{':
                $result = $stdClass ? new stdClass : array();
                ++$pos;
                while($encode{$pos} !== '}') {
                    $tmp = FastJSON::__decodeString($encode, $pos);
                    ++$pos;
                    if($stdClass)
                        $result->$tmp = FastJSON::__decode($encode, $pos, $slen, $stdClass);
                    else
                        $result[$tmp] = FastJSON::__decode($encode, $pos, $slen, $stdClass);
                    if($encode{$pos} === ',')
                        ++$pos;
                }
                ++$pos;
                break;
            case '"':
                switch($encode{++$pos}) {
                    case '"':
                        $result = "";
                        break;
                    default:
                        $result = FastJSON::__decodeString($encode, $pos);
                        break;
                }
                ++$pos;
                break;
            default:
                $tmp = '';
                preg_replace('/^(\-)?([0-9]+)(\.[0-9]+)?([eE]\+[0-9]+)?/e', '$tmp = "\\1\\2\\3\\4"', substr($encode, $pos));
                if($tmp !== '') {
                    $pos += strlen($tmp);
                    $nint = intval($tmp);
                    $nfloat = floatval($tmp);
                    $result = $nfloat == $nint ? $nint : $nfloat;
                }
                break;
        }
        return $result;
    }
    static private function __decodeString(&$encode, &$pos) {
        $replacement = FastJSON::__getStaticReplacement();
        $endString = FastJSON::__endString($encode, $pos, $pos);
        $result = str_replace($replacement['replace'], $replacement['find'], substr($encode, $pos, $endString));
        $pos += $endString;
        return $result;
    }
    static private function __endString(&$encode, $position, &$pos) {
        do {
            $position = strpos($encode, '"', $position + 1);
        }while($position !== false && FastJSON::__slashedChar($encode, $position - 1));
        if($position === false)
            trigger_error('', E_USER_WARNING);
        return $position - $pos;
    }
    static private function __exit($str, $a, $b) {
        exit($a.'FATAL: FastJSON decode method failure [malicious or incorrect JSON string]');
    }
    static private function __slashedChar(&$encode, $position) {
        $pos = 0;
        while($encode{$position--} === '\\')
            $pos++;
        return $pos % 2;
    }
}
?>

References

1. json_decode
2. Services_JSON
3. Zend_JSON
4. FastJSON