Parsing Javascript (not JSON) in PHP

Question

I have a php string containing the serialization of a javascript object :

$string = '{fu:"bar",baz:["bat"]}';

The actual string is far more complicated, of course, but still well-formed javascript. This is not standard JSON, so json_decode fails. Do you know any php library that would parse this string and return a php associative array ?

Answer 1

This sounded like a fun challenge, so I coded up a tiny parser :D

class JsParserException extends Exception {}
function parse_jsobj($str, &$data) {
    $str = trim($str);
    if(strlen($str) < 1) return;

    if($str{0} != '{') {
        throw new JsParserException('The given string is not a JS object');
    }
    $str = substr($str, 1);

    /* While we have data, and it's not the end of this dict (the comma is needed for nested dicts) */
    while(strlen($str) && $str{0} != '}' && $str{0} != ',') { 
        /* find the key */
        if($str{0} == "'" || $str{0} == '"') {
            /* quoted key */
            list($str, $key) = parse_jsdata($str, ':');
        } else {
            $match = null;
            /* unquoted key */
            if(!preg_match('/^s*[a-zA-z_][a-zA-Z_d]*s*:/', $str, $match)) {
            throw new JsParserException('Invalid key ("'.$str.'")');
            }   
            $key = $match[0];
            $str = substr($str, strlen($key));
            $key = trim(substr($key, 0, -1)); /* discard the ':' */
        }

        list($str, $data[$key]) = parse_jsdata($str, '}');
    }
    "Finshed dict. Str: '$str'
";
    return substr($str, 1);
}

function comma_or_term_pos($str, $term) {
    $cpos = strpos($str, ',');
    $tpos = strpos($str, $term);
    if($cpos === false && $tpos === false) {
        throw new JsParserException('unterminated dict or array');
    } else if($cpos === false) {
        return $tpos;
    } else if($tpos === false) {
        return $cpos;
    }
    return min($tpos, $cpos);
}

function parse_jsdata($str, $term="}") {
    $str = trim($str);


    if(is_numeric($str{0}."0")) {
        /* a number (int or float) */
        $newpos = comma_or_term_pos($str, $term);
        $num = trim(substr($str, 0, $newpos));
        $str = substr($str, $newpos+1); /* discard num and comma */
        if(!is_numeric($num)) {
            throw new JsParserException('OOPSIE while parsing number: "'.$num.'"');
        }
        return array(trim($str), $num+0);
    } else if($str{0} == '"' || $str{0} == "'") {
        /* string */
        $q = $str{0};
        $offset = 1;
        do {
            $pos = strpos($str, $q, $offset);
            $offset = $pos;
        } while($str{$pos-1} == '\'); /* find un-escaped quote */
        $data = substr($str, 1, $pos-1);
        $str = substr($str, $pos);
        $pos = comma_or_term_pos($str, $term);
        $str = substr($str, $pos+1);        
        return array(trim($str), $data);
    } else if($str{0} == '{') {
        /* dict */
        $data = array();
        $str = parse_jsobj($str, $data);
        return array($str, $data);
    } else if($str{0} == '[') {
        /* array */
        $arr = array();
        $str = substr($str, 1);
        while(strlen($str) && $str{0} != $term && $str{0} != ',') {
            $val = null;
            list($str, $val) = parse_jsdata($str, ']');
            $arr[] = $val;
            $str = trim($str);
        }
        $str = trim(substr($str, 1));
        return array($str, $arr);
    } else if(stripos($str, 'true') === 0) {
        /* true */
        $pos = comma_or_term_pos($str, $term);
        $str = substr($str, $pos+1); /* discard terminator */
        return array(trim($str), true);
    } else if(stripos($str, 'false') === 0) {
        /* false */
        $pos = comma_or_term_pos($str, $term);
        $str = substr($str, $pos+1); /* discard terminator */
        return array(trim($str), false);
    } else if(stripos($str, 'null') === 0) {
        /* null */
        $pos = comma_or_term_pos($str, $term);
        $str = substr($str, $pos+1); /* discard terminator */
        return array(trim($str), null);
    } else if(strpos($str, 'undefined') === 0) {
        /* null */
        $pos = comma_or_term_pos($str, $term);
        $str = substr($str, $pos+1); /* discard terminator */
        return array(trim($str), null);
    } else {
        throw new JsParserException('Cannot figure out how to parse "'.$str.'" (term is '.$term.')');
    }
}

Usage:

$data = '{fu:"bar",baz:["bat"]}';    
$parsed = array();    
parse_jsobj($data, $parsed);    
var_export($parsed);

Gives:

array (
  'fu' => 'bar',
  'baz' =>
  array (
    0 => 'bat',
  ),
)

Tested with these strings:

'{fu:"bar",baz:["bat"]}',
'{rec:{rec:{rec:false}}}',
'{foo:[1,2,[3,4]]}',
'{fu:{fu:"bar"},bar:{fu:"bar"}}',
'{"quoted key":[1,2,3]}',
'{und:undefined,"baz":[1,2,"3"]}',
'{arr:["a","b"],"baz":"foo","gar":{"faz":false,t:"2"},f:false}',