path: root/plugins/managesieve/lib/rcube_sieve.php

<?php

/*
  Classes for managesieve operations (using PEAR::Net_Sieve)

  Author: Aleksander Machniak <alec@alec.pl>

  $Id$

*/

//  Sieve Language Basics: http://www.ietf.org/rfc/rfc5228.txt

define('SIEVE_ERROR_CONNECTION', 1);
define('SIEVE_ERROR_LOGIN', 2);
define('SIEVE_ERROR_NOT_EXISTS', 3);    // script not exists
define('SIEVE_ERROR_INSTALL', 4);       // script installation
define('SIEVE_ERROR_ACTIVATE', 5);      // script activation
define('SIEVE_ERROR_DELETE', 6);        // script deletion
define('SIEVE_ERROR_INTERNAL', 7);      // internal error
define('SIEVE_ERROR_DEACTIVATE', 8);    // script activation
define('SIEVE_ERROR_OTHER', 255);       // other/unknown error


class rcube_sieve
{
    private $sieve;                 // Net_Sieve object
    private $error = false;         // error flag
    private $list = array();        // scripts list

    public $script;                 // rcube_sieve_script object
    public $current;                // name of currently loaded script
    private $disabled;              // array of disabled extensions


    /**
     * Object constructor
     *
     * @param string  Username (for managesieve login)
     * @param string  Password (for managesieve login)
     * @param string  Managesieve server hostname/address
     * @param string  Managesieve server port number
     * @param string  Managesieve authentication method 
     * @param boolean Enable/disable TLS use
     * @param array   Disabled extensions
     * @param boolean Enable/disable debugging
     */
    public function __construct($username, $password='', $host='localhost', $port=2000,
        $auth_type=null, $usetls=true, $disabled=array(), $debug=false)
    {
        $this->sieve = new Net_Sieve();

        if ($debug) {
            $this->sieve->setDebug(true, array($this, 'debug_handler'));
        }
        if (PEAR::isError($this->sieve->connect($host, $port, NULL, $usetls))) {
            return $this->_set_error(SIEVE_ERROR_CONNECTION);
        }
        if (PEAR::isError($this->sieve->login($username, $password,
            $auth_type ? strtoupper($auth_type) : null))
        ) {
            return $this->_set_error(SIEVE_ERROR_LOGIN);
        }
        $this->disabled = $disabled;
    }

    public function __destruct() {
        $this->sieve->disconnect();
    }

    /**
     * Getter for error code
     */
    public function error()
    {
        return $this->error ? $this->error : false;
    }

    /**
     * Saves current script into server
     */
    public function save($name = null)
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        if (!$this->script)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        if (!$name)
            $name = $this->current;

        $script = $this->script->as_text();

        if (!$script)
            $script = '/* empty script */';

        if (PEAR::isError($this->sieve->installScript($name, $script)))
            return $this->_set_error(SIEVE_ERROR_INSTALL);

        return true;
    }

    /**
     * Saves text script into server
     */
    public function save_script($name, $content = null)
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        if (!$content)
            $content = '/* empty script */';

        if (PEAR::isError($this->sieve->installScript($name, $content)))
            return $this->_set_error(SIEVE_ERROR_INSTALL);

        return true;
    }

    /**
     * Activates specified script
     */
    public function activate($name = null)
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        if (!$name)
            $name = $this->current;

        if (PEAR::isError($this->sieve->setActive($name)))
            return $this->_set_error(SIEVE_ERROR_ACTIVATE);

        return true;
    }

    /**
     * De-activates specified script
     */
    public function deactivate()
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        if (PEAR::isError($this->sieve->setActive('')))
            return $this->_set_error(SIEVE_ERROR_DEACTIVATE);

        return true;
    }

    /**
     * Removes specified script
     */
    public function remove($name = null)
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        if (!$name)
            $name = $this->current;

        // script must be deactivated first
        if ($name == $this->sieve->getActive())
            if (PEAR::isError($this->sieve->setActive('')))
                return $this->_set_error(SIEVE_ERROR_DELETE);

        if (PEAR::isError($this->sieve->removeScript($name)))
            return $this->_set_error(SIEVE_ERROR_DELETE);

        if ($name == $this->current)
            $this->current = null;

        return true;
    }

    /**
     * Gets list of supported by server Sieve extensions
     */
    public function get_extensions()
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        $ext = $this->sieve->getExtensions();
        // we're working on lower-cased names
        $ext = array_map('strtolower', (array) $ext);

        if ($this->script) {
            $supported = $this->script->get_extensions();
            foreach ($ext as $idx => $ext_name)
                if (!in_array($ext_name, $supported))
                    unset($ext[$idx]);
        }

        return array_values($ext);
    }

    /**
     * Gets list of scripts from server
     */
    public function get_scripts()
    {
        if (!$this->list) {

            if (!$this->sieve)
                return $this->_set_error(SIEVE_ERROR_INTERNAL);

            $this->list = $this->sieve->listScripts();

            if (PEAR::isError($this->list))
                return $this->_set_error(SIEVE_ERROR_OTHER);
        }

        return $this->list;
    }

    /**
     * Returns active script name
     */
    public function get_active()
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        return $this->sieve->getActive();
    }

    /**
     * Loads script by name
     */
    public function load($name)
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        if ($this->current == $name)
            return true;

        $script = $this->sieve->getScript($name);

        if (PEAR::isError($script))
            return $this->_set_error(SIEVE_ERROR_OTHER);

        // try to parse from Roundcube format
        $this->script = $this->_parse($script);

        $this->current = $name;

        return true;
    }

    /**
     * Loads script from text content
     */
    public function load_script($script)
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        // try to parse from Roundcube format
        $this->script = $this->_parse($script);
    }

    /**
     * Creates rcube_sieve_script object from text script
     */
    private function _parse($txt)
    {
        // try to parse from Roundcube format
        $script = new rcube_sieve_script($txt, $this->disabled);

        // ... else try to import from different formats
        if (empty($script->content)) {
            $script = $this->_import_rules($txt);
            $script = new rcube_sieve_script($script, $this->disabled);
        }

        // replace all elsif with if+stop, we support only ifs
        foreach ($script->content as $idx => $rule) {
            if (!isset($script->content[$idx+1])
                || preg_match('/^else|elsif$/', $script->content[$idx+1]['type'])) {
                // 'stop' not found?
                if (!preg_match('/^(stop|vacation)$/', $rule['actions'][count($rule['actions'])-1]['type'])) {
                    $script->content[$idx]['actions'][] = array(
                        'type' => 'stop'
                    );
                }
            }
        }

        return $script;
    }

    /**
     * Gets specified script as text
     */
    public function get_script($name)
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        $content = $this->sieve->getScript($name);

        if (PEAR::isError($content))
            return $this->_set_error(SIEVE_ERROR_OTHER);

        return $content;
    }

    /**
     * Creates empty script or copy of other script
     */
    public function copy($name, $copy)
    {
        if (!$this->sieve)
            return $this->_set_error(SIEVE_ERROR_INTERNAL);

        if ($copy) {
            $content = $this->sieve->getScript($copy);

            if (PEAR::isError($content))
                return $this->_set_error(SIEVE_ERROR_OTHER);
        }

        return $this->save_script($name, $content);
    }

    private function _import_rules($script)
    {
        $i = 0;
        $name = array();

        // Squirrelmail (Avelsieve)
        if ($tokens = preg_split('/(#START_SIEVE_RULE.*END_SIEVE_RULE)\n/', $script, -1, PREG_SPLIT_DELIM_CAPTURE)) {
            foreach($tokens as $token) {
                if (preg_match('/^#START_SIEVE_RULE.*/', $token, $matches)) {
                    $name[$i] = "unnamed rule ".($i+1);
                    $content .= "# rule:[".$name[$i]."]\n";
                }
                elseif (isset($name[$i])) {
                    // This preg_replace is added because I've found some Avelsieve scripts
                    // with rules containing "if" here. I'm not sure it was working
                    // before without this or not.
                    $token = preg_replace('/^if\s+/', '', trim($token));
                    $content .= "if $token\n";
                    $i++;
                }
            }
        }
        // Horde (INGO)
        else if ($tokens = preg_split('/(# .+)\r?\n/i', $script, -1, PREG_SPLIT_DELIM_CAPTURE)) {
            foreach($tokens as $token) {
                if (preg_match('/^# (.+)/i', $token, $matches)) {
                    $name[$i] = $matches[1];
                    $content .= "# rule:[" . $name[$i] . "]\n";
                }
                elseif (isset($name[$i])) {
                    $token = str_replace(":comparator \"i;ascii-casemap\" ", "", $token);
                    $content .= $token . "\n";
                    $i++;
                }
            }
        }

        return $content;
    }

    private function _set_error($error)
    {
        $this->error = $error;
        return false;
    }

    /**
     * This is our own debug handler for connection
     */
    public function debug_handler(&$sieve, $message)
    {
        write_log('sieve', preg_replace('/\r\n$/', '', $message));
    }
}


class rcube_sieve_script
{
    public $content = array();      // script rules array

    private $supported = array(     // extensions supported by class
        'fileinto',
        'reject',
        'ereject',
        'copy',                     // RFC3894
        'vacation',                 // RFC5230
    // TODO: (most wanted first) body, imapflags, notify, regex
    );

    /**
     * Object constructor
     *
     * @param  string  Script's text content
     * @param  array   Disabled extensions
     */
    public function __construct($script, $disabled=NULL)
    {
        if (!empty($disabled))
            foreach ($disabled as $ext)
                if (($idx = array_search($ext, $this->supported)) !== false)
                    unset($this->supported[$idx]);

        $this->content = $this->_parse_text($script);
    }

    /**
     * Adds script contents as text to the script array (at the end)
     *
     * @param    string    Text script contents
     */
    public function add_text($script)
    {
        $content = $this->_parse_text($script);
        $result = false;

        // check existsing script rules names
        foreach ($this->content as $idx => $elem) {
            $names[$elem['name']] = $idx;
        }

        foreach ($content as $elem) {
            if (!isset($names[$elem['name']])) {
                array_push($this->content, $elem);
                $result = true;
            }
        }

        return $result;
    }

    /**
     * Adds rule to the script (at the end)
     *
     * @param string Rule name
     * @param array  Rule content (as array)
     */
    public function add_rule($content)
    {
        // TODO: check this->supported
        array_push($this->content, $content);
        return sizeof($this->content)-1;
    }

    public function delete_rule($index)
    {
        if(isset($this->content[$index])) {
            unset($this->content[$index]);
            return true;
        }
        return false;
    }

    public function size()
    {
        return sizeof($this->content);
    }

    public function update_rule($index, $content)
    {
        // TODO: check this->supported
        if ($this->content[$index]) {
            $this->content[$index] = $content;
            return $index;
        }
        return false;
    }

    /**
     * Returns script as text
     */
    public function as_text()
    {
        $script = '';
        $exts = array();
        $idx = 0;

        // rules
        foreach ($this->content as $rule) {
            $extension = '';
            $tests = array();
            $i = 0;

            // header
            $script .= '# rule:[' . $rule['name'] . "]\n";

            // constraints expressions
            foreach ($rule['tests'] as $test) {
                $tests[$i] = '';
                switch ($test['test']) {
                case 'size':
                    $tests[$i] .= ($test['not'] ? 'not ' : '');
                    $tests[$i] .= 'size :' . ($test['type']=='under' ? 'under ' : 'over ') . $test['arg'];
                    break;
                case 'true':
                    $tests[$i] .= ($test['not'] ? 'not true' : 'true');
                    break;
                case 'exists':
                    $tests[$i] .= ($test['not'] ? 'not ' : '');
                    if (is_array($test['arg']))
                        $tests[$i] .= 'exists ["' . implode('", "', $this->_escape_string($test['arg'])) . '"]';
                    else
                        $tests[$i] .= 'exists "' . $this->_escape_string($test['arg']) . '"';
                    break;
                case 'header':
                    $tests[$i] .= ($test['not'] ? 'not ' : '');
                    $tests[$i] .= 'header :' . $test['type'];
                    if (is_array($test['arg1']))
                        $tests[$i] .= ' ["' . implode('", "', $this->_escape_string($test['arg1'])) . '"]';
                    else
                        $tests[$i] .= ' "' . $this->_escape_string($test['arg1']) . '"';
                    if (is_array($test['arg2']))
                        $tests[$i] .= ' ["' . implode('", "', $this->_escape_string($test['arg2'])) . '"]';
                    else
                        $tests[$i] .= ' "' . $this->_escape_string($test['arg2']) . '"';
                    break;
                }
                $i++;
            }

//          $script .= ($idx>0 ? 'els' : '').($rule['join'] ? 'if allof (' : 'if anyof (');
            // disabled rule: if false #....
            $script .= 'if' . ($rule['disabled'] ? ' false #' : '');
            $script .= $rule['join'] ? ' allof (' : ' anyof (';
            if (sizeof($tests) > 1)
                $script .= implode(", ", $tests);
            else if (sizeof($tests))
                $script .= $tests[0];
            else
                $script .= 'true';
            $script .= ")\n{\n";

            // action(s)
            foreach ($rule['actions'] as $action) {
                switch ($action['type']) {
                case 'fileinto':
                    array_push($exts, 'fileinto');
                    $script .= "\tfileinto ";
                    if ($action['copy']) {
                        $script .= ':copy ';
                        array_push($exts, 'copy');
                    }
                    $script .= "\"" . $this->_escape_string($action['target']) . "\";\n";
                    break;
                case 'redirect':
                    $script .= "\tredirect ";
                    if ($action['copy']) {
                        $script .= ':copy ';
                        array_push($exts, 'copy');
                    }
                    $script .= "\"" . $this->_escape_string($action['target']) . "\";\n";
                    break;
                case 'reject':
                case 'ereject':
                    array_push($exts, $action['type']);
                    if (strpos($action['target'], "\n")!==false)
                        $script .= "\t".$action['type']." text:\n" . $action['target'] . "\n.\n;\n";
                    else
                        $script .= "\t".$action['type']." \"" . $this->_escape_string($action['target']) . "\";\n";
                    break;
                case 'keep':
                case 'discard':
                case 'stop':
                    $script .= "\t" . $action['type'] .";\n";
                    break;
                case 'vacation':
                    array_push($exts, 'vacation');
                    $script .= "\tvacation";
                    if ($action['days'])
                        $script .= " :days " . $action['days'];
                    if ($action['addresses'])
                        $script .= " :addresses " . $this->_print_list($action['addresses']);
                    if ($action['subject'])
                        $script .= " :subject \"" . $this->_escape_string($action['subject']) . "\"";
                    if ($action['handle'])
                        $script .= " :handle \"" . $this->_escape_string($action['handle']) . "\"";
                    if ($action['from'])
                        $script .= " :from \"" . $this->_escape_string($action['from']) . "\"";
                    if ($action['mime'])
                        $script .= " :mime";
                    if (strpos($action['reason'], "\n")!==false)
                        $script .= " text:\n" . $action['reason'] . "\n.\n;\n";
                    else
                        $script .= " \"" . $this->_escape_string($action['reason']) . "\";\n";
                    break;
                }
            }

            $script .= "}\n";
            $idx++;
        }

        // requires
        if (!empty($exts))
            $script = 'require ["' . implode('","', array_unique($exts)) . "\"];\n" . $script;

        return $script;
    }

    /**
     * Returns script object
     *
     */
    public function as_array()
    {
        return $this->content;
    }

    /**
     * Returns array of supported extensions
     *
     */
    public function get_extensions()
    {
        return array_values($this->supported);
    }

    /**
     * Converts text script to rules array
     *
     * @param string Text script
     */
    private function _parse_text($script)
    {
        $i = 0;
        $content = array();

        // remove C comments
        $script = preg_replace('|/\*.*?\*/|sm', '', $script);

        // tokenize rules
        if ($tokens = preg_split('/(# rule:\[.*\])\r?\n/', $script, -1, PREG_SPLIT_DELIM_CAPTURE)) {
            foreach($tokens as $token) {
                if (preg_match('/^# rule:\[(.*)\]/', $token, $matches)) {
                    $content[$i]['name'] = $matches[1];
                }
                else if (isset($content[$i]['name']) && sizeof($content[$i]) == 1) {
                    if ($rule = $this->_tokenize_rule($token)) {
                        $content[$i] = array_merge($content[$i], $rule);
                        $i++;
                    }
                    else // unknown rule format
                        unset($content[$i]);
                }
            }
        }

        return $content;
    }

    /**
     * Convert text script fragment to rule object
     *
     * @param string Text rule
     */
    private function _tokenize_rule($content)
    {
        $result = NULL;

        if (preg_match('/^(if|elsif|else)\s+((true|false|not\s+true|allof|anyof|exists|header|not|size)(.*))\s+\{(.*)\}$/sm',
            trim($content), $matches)) {

            $tests = trim($matches[2]);

            // disabled rule (false + comment): if false #.....
            if ($matches[3] == 'false') {
                $tests = preg_replace('/^false\s+#\s+/', '', $tests);
                $disabled = true;
            }
            else
                $disabled = false;

            list($tests, $join) = $this->_parse_tests($tests);
            $actions = $this->_parse_actions(trim($matches[5]));

            if ($tests && $actions)
                $result = array(
                    'type'     => $matches[1],
                    'tests'    => $tests,
                    'actions'  => $actions,
                    'join'     => $join,
                    'disabled' => $disabled,
            );
        }

        return $result;
    }

    /**
     * Parse body of actions section
     *
     * @param string Text body
     * @return array Array of parsed action type/target pairs
     */
    private function _parse_actions($content)
    {
        $result = NULL;

        // supported actions
        $patterns[] = '^\s*discard;';
        $patterns[] = '^\s*keep;';
        $patterns[] = '^\s*stop;';
        $patterns[] = '^\s*redirect\s+(.*?[^\\\]);';
        if (in_array('fileinto', $this->supported))
            $patterns[] = '^\s*fileinto\s+(.*?[^\\\]);';
        if (in_array('reject', $this->supported)) {
            $patterns[] = '^\s*reject\s+text:(.*)\n\.\n;';
            $patterns[] = '^\s*reject\s+(.*?[^\\\]);';
            $patterns[] = '^\s*ereject\s+text:(.*)\n\.\n;';
            $patterns[] = '^\s*ereject\s+(.*?[^\\\]);';
        }
        if (in_array('vacation', $this->supported))
            $patterns[] = '^\s*vacation\s+(.*?[^\\\]);';

        $pattern = '/(' . implode('$)|(', $patterns) . '$)/ms';

        // parse actions body
        if (preg_match_all($pattern, $content, $mm, PREG_SET_ORDER)) {
            foreach ($mm as $m) {
                $content = trim($m[0]);

                if(preg_match('/^(discard|keep|stop)/', $content, $matches)) {
                    $result[] = array('type' => $matches[1]);
                }
                else if(preg_match('/^fileinto/', $content)) {
                    $target = $m[sizeof($m)-1];
                    $copy = false;
                    if (preg_match('/^:copy\s+/', $target)) {
                        $target = preg_replace('/^:copy\s+/', '', $target);
                        $copy = true;
                    }
                    $result[] = array('type' => 'fileinto', 'copy' => $copy,
                        'target' => $this->_parse_string($target));
                }
                else if(preg_match('/^redirect/', $content)) {
                    $target = $m[sizeof($m)-1];
                    $copy = false;
                    if (preg_match('/^:copy\s+/', $target)) {
                        $target = preg_replace('/^:copy\s+/', '', $target);
                        $copy = true;
                    }
                    $result[] = array('type' => 'redirect', 'copy' => $copy,
                        'target' => $this->_parse_string($target));
                }
                else if(preg_match('/^(reject|ereject)\s+(.*);$/sm', $content, $matches)) {
                    $result[] = array('type' => $matches[1], 'target' => $this->_parse_string($matches[2]));
                }
                else if(preg_match('/^vacation\s+(.*);$/sm', $content, $matches)) {
                    $vacation = array('type' => 'vacation');

                    if (preg_match('/:days\s+([0-9]+)/', $content, $vm)) {
                        $vacation['days'] = $vm[1];
                        $content = preg_replace('/:days\s+([0-9]+)/', '', $content);
                    }
                    if (preg_match('/:subject\s+"(.*?[^\\\])"/', $content, $vm)) {
                        $vacation['subject'] = $vm[1];
                        $content = preg_replace('/:subject\s+"(.*?[^\\\])"/', '', $content);
                    }
                    if (preg_match('/:addresses\s+\[(.*?[^\\\])\]/', $content, $vm)) {
                        $vacation['addresses'] = $this->_parse_list($vm[1]);
                        $content = preg_replace('/:addresses\s+\[(.*?[^\\\])\]/', '', $content);
                    }
                    if (preg_match('/:handle\s+"(.*?[^\\\])"/', $content, $vm)) {
                        $vacation['handle'] = $vm[1];
                        $content = preg_replace('/:handle\s+"(.*?[^\\\])"/', '', $content);
                    }
                    if (preg_match('/:from\s+"(.*?[^\\\])"/', $content, $vm)) {
                        $vacation['from'] = $vm[1];
                        $content = preg_replace('/:from\s+"(.*?[^\\\])"/', '', $content);
                    }

                    $content = preg_replace('/^vacation/', '', $content);
                    $content = preg_replace('/;$/', '', $content);
                    $content = trim($content);

                    if (preg_match('/^:mime/', $content, $vm)) {
                        $vacation['mime'] = true;
                        $content = preg_replace('/^:mime/', '', $content);
                    }

                    $vacation['reason'] = $this->_parse_string($content);

                    $result[] = $vacation;
                }
            }
        }

        return $result;
    }

    /**
     * Parse test/conditions section
     *
     * @param string Text
     */
    private function _parse_tests($content)
    {
        $result = NULL;

        // lists
        if (preg_match('/^(allof|anyof)\s+\((.*)\)$/sm', $content, $matches)) {
            $content = $matches[2];
            $join = $matches[1]=='allof' ? true : false;
        }
        else
            $join = false;

        // supported tests regular expressions
        // TODO: comparators, envelope
        $patterns[] = '(not\s+)?(exists)\s+\[(.*?[^\\\])\]';
        $patterns[] = '(not\s+)?(exists)\s+(".*?[^\\\]")';
        $patterns[] = '(not\s+)?(true)';
        $patterns[] = '(not\s+)?(size)\s+:(under|over)\s+([0-9]+[KGM]{0,1})';
        $patterns[] = '(not\s+)?(header)\s+:(contains|is|matches)\s+\[(.*?[^\\\]")\]\s+\[(.*?[^\\\]")\]';
        $patterns[] = '(not\s+)?(header)\s+:(contains|is|matches)\s+(".*?[^\\\]")\s+(".*?[^\\\]")';
        $patterns[] = '(not\s+)?(header)\s+:(contains|is|matches)\s+\[(.*?[^\\\]")\]\s+(".*?[^\\\]")';
        $patterns[] = '(not\s+)?(header)\s+:(contains|is|matches)\s+(".*?[^\\\]")\s+\[(.*?[^\\\]")\]';

        // join patterns...
        $pattern = '/(' . implode(')|(', $patterns) . ')/';

        // ...and parse tests list
        if (preg_match_all($pattern, $content, $matches, PREG_SET_ORDER)) {
            foreach ($matches as $match) {
                $size = sizeof($match);

                if (preg_match('/^(not\s+)?size/', $match[0])) {
                    $result[] = array(
                        'test' => 'size',
                        'not'  => $match[$size-4] ? true : false,
                        'type' => $match[$size-2], // under/over
                        'arg'  => $match[$size-1], // value
                    );
                }
                else if (preg_match('/^(not\s+)?header/', $match[0])) {
                    $result[] = array(
                        'test' => 'header',
                        'not'  => $match[$size-5] ? true : false,
                        'type' => $match[$size-3], // is/contains/matches
                        'arg1' => $this->_parse_list($match[$size-2]), // header(s)
                        'arg2' => $this->_parse_list($match[$size-1]), // string(s)
                    );
                }
                else if (preg_match('/^(not\s+)?exists/', $match[0])) {
                    $result[] = array(
                        'test' => 'exists',
                        'not'  => $match[$size-3] ? true : false,
                        'arg'  => $this->_parse_list($match[$size-1]), // header(s)
                    );
                }
                else if (preg_match('/^(not\s+)?true/', $match[0])) {
                    $result[] = array(
                        'test' => 'true',
                        'not'  => $match[$size-2] ? true : false,
                    );
                }
            }
        }

        return array($result, $join);
    }

    /**
     * Parse string value
     *
     * @param string Text
     */
    private function _parse_string($content)
    {
        $text = '';
        $content = trim($content);

        if (preg_match('/^text:(.*)\.$/sm', $content, $matches))
            $text = trim($matches[1]);
        else if (preg_match('/^"(.*)"$/', $content, $matches))
            $text = str_replace('\"', '"', $matches[1]);

        return $text;
    }

    /**
     * Escape special chars in string value
     *
     * @param string Text
     */
    private function _escape_string($content)
    {
        $replace['/"/'] = '\\"';

        if (is_array($content)) {
            for ($x=0, $y=sizeof($content); $x<$y; $x++)
                $content[$x] = preg_replace(array_keys($replace),
                    array_values($replace), $content[$x]);

            return $content;
        }
        else
            return preg_replace(array_keys($replace), array_values($replace), $content);
    }

    /**
     * Parse string or list of strings to string or array of strings
     *
     * @param string Text
     */
    private function _parse_list($content)
    {
        $result = array();

        for ($x=0, $len=strlen($content); $x<$len; $x++) {
            switch ($content[$x]) {
            case '\\':
                $str .= $content[++$x];
                break;
            case '"':
                if (isset($str)) {
                    $result[] = $str;
                    unset($str);
                }
                else
                    $str = '';
                break;
            default:
                if(isset($str))
                    $str .= $content[$x];
            break;
            }
        }

        if (sizeof($result)>1)
            return $result;
        else if (sizeof($result) == 1)
            return $result[0];
        else
            return NULL;
    }

    /**
     * Convert array of elements to list of strings
     *
     * @param string Text
     */
    private function _print_list($list)
    {
        $list = (array) $list;
        foreach($list as $idx => $val)
            $list[$idx] = $this->_escape_string($val);

        return '["' . implode('","', $list) . '"]';
    }
}