";
        debug_print_backtrace();
        die();
    }

    private function _push_stack()
    {
        $this->stack[] = [ $this->r, $this->nodes ];
    }

    private function _pop_stack()
    {
        list($this->r, $this->nodes) = array_pop($this->stack);
    }

    private function _get_var($name, $retNoKey = false)
    {
        $keys = array_map('trim', explode('.', $name));
        if ($retNoKey && ! array_key_exists($keys[0], $this->r)) {
            return KEY_NOT_EXISTS;
        }

        $val = $this->r;
        foreach ($keys as $k) {
            $val = (isset($val[$k]) ? $val[$k] : null);
        }

        return template_escape($val);
    }

    /**
     * IF node
     * \code
     * {{ if <$var> }}...[{{ else }} ...] {{ endif }}
     * {{ if <$var>== }}...[{{ else }} ...]{{ endif }}
     * {{ if <$var>!= }}...[{{ else }} ...]{{ endif }}
     * \endcode
     */
    private function _replcb_if($args)
    {
        if (strpos($args[2], '==') > 0) {
            list($a,$b) = array_map('trim', explode('==', $args[2]));
            $a = $this->_get_var($a);
            if ($b[0] == '$') {
                $b =  $this->_get_var($b);
            }
            $val = ($a == $b);
        } elseif (strpos($args[2], '!=') > 0) {
            list($a,$b) = array_map('trim', explode('!=', $args[2]));
            $a = $this->_get_var($a);
            if ($b[0] == '$') {
                $b =  $this->_get_var($b);
            }
            $val = ($a != $b);
        } else {
            $val = $this->_get_var($args[2]);
        }
        $x = preg_split("|{{ *else *}}|", $args[3]);

        return ( ($val) ? $x[0] : (isset($x[1]) ? $x[1] : EMPTY_STR));
    }

    /**
     * FOR node
     * \code
     * {{ for <$var> as $name }}...{{ endfor }}
     * {{ for <$var> as $key=>$name }}...{{ endfor }}
     * \endcode
     */
    private function _replcb_for($args)
    {
        $m = array_map('trim', explode(" as ", $args[2]));
        $x = explode('=>', $m[1]);
        if (count($x) == 1) {
            $varname = $x[0];
            $keyname = EMPTY_STR;
        } else {
            list($keyname, $varname) = $x;
        }
        if ($m[0] == EMPTY_STR || $varname == EMPTY_STR || is_null($varname)) {
            die("template error: 'for " . $m[0] . " as " . $varname . "'") ;
        }

        $vals = $this->_get_var($m[0]);
        $ret = EMPTY_STR;
        if (!is_array($vals)) {
            return $ret;
        }

        foreach ($vals as $k => $v) {
            $this->_push_stack();
            $r = $this->r;
            $r[$varname] = $v;
            if ($keyname != EMPTY_STR) {
                $r[$keyname] = (($k === 0) ? '0' : $k);
            }
            $ret .=  $this->replace($args[3], $r);
            $this->_pop_stack();
        }

        return $ret;
    }

    /**
     * INC node
     * \code
     * {{ inc  [with $var1=$var2] }}{{ endinc }}
     * \endcode
     */
    private function _replcb_inc($args)
    {
        if (strpos($args[2], 'with')) {
            list($tplfile, $newctx) = array_map('trim', explode("with", $args[2]));
        } else {
            $tplfile = trim($args[2]);
            $newctx = null;
        }

        if ($tplfile[0] == '$') {
            $tplfile = $this->_get_var($tplfile);
        }

        $this->_push_stack();
        $r = $this->r;
        if (! is_null($newctx)) {
            list($a,$b) = array_map('trim', explode('=', $newctx));
            $r[$a] = $this->_get_var($b);
        }
        $this->nodes = [];
        $tpl = Theme::get_template($tplfile);
        $ret = $this->replace($tpl, $r);
        $this->_pop_stack();

        return $ret;
    }

    /**
     * DEBUG node
     * \code
     * {{ debug $var [$var [$var [...]]] }}{{ enddebug }}
     * \endcode
     * replace node with 
var_dump($var, $var, ...);
     */
    private function _replcb_debug($args)
    {
        $vars = array_map('trim', explode(" ", $args[2]));
        $vars[] = $args[1];

        $ret = "
";
        foreach ($vars as $var) {
            $ret .= htmlspecialchars(var_export($this->_get_var($var), true));
            $ret .= "\n";
        }
        $ret .= "
";

        return $ret;
    }

    private function _replcb_node($m)
    {
        $node = $this->nodes[$m[1]];
        if (method_exists($this, "_replcb_" . $node[1])) {
            $s = call_user_func([$this, "_replcb_" . $node[1]], $node);
        } else {
            $s = "";
        }
        return preg_replace_callback('/\|\|([0-9]+)\|\|/', [$this, "_replcb_node"], $s);
    }

    private function _replcb($m)
    {
        //var_dump(array_map('htmlspecialchars', $m));
        $this->done = false;
        $this->nodes[] = (array) $m;

        return "||" . (count($this->nodes) - 1) . "||";
    }

    private function _build_nodes($s)
    {
        $this->done = false;
        while (!$this->done) {
            $this->done = true;
            $s = preg_replace_callback('|{{ *([a-z]*) *([^}]*)}}([^{]*({{ *else *}}[^{]*)?){{ *end\1 *}}|', [$this, "_replcb"], $s);
            if ($s == null) {
                $this->_preg_error();
            }
        }
        //({{ *else *}}[^{]*)?
        krsort($this->nodes);

        return $s;
    }

    private function var_replace($s)
    {
        $m = [];
        /** regexp:
         * \$                       literal $
         * (\[)?                    optional open square bracket
         * ([a-zA-Z0-9-_]+\.?)+     var name, followed by optional
         *                          dot, repeated at least 1 time
         * (?(1)\])                 if there was opened square bracket
         *                          (subgrup 1), match close bracket
         */
        if (preg_match_all('/\$(\[)?([a-zA-Z0-9-_]+\.?)+(?(1)])/', $s, $m)) {
            foreach ($m[0] as $var) {
                $exp = str_replace(["[", "]"], ["", ""], $var);
                $exptks = explode("|", $exp);

                $varn = $exptks[0];
                unset($exptks[0]);
                $val = $this->_get_var($varn, true);
                if ($val != KEY_NOT_EXISTS) {
                    /* run filters */
                    /*
                     * Filter are in form of:
                     * filtername:arg:arg:arg
                     *
                     * "filtername" is function name
                     * "arg"s are optional, var value is appended to the end
                     *          if one "arg"==='x' , is replaced with var value
                     *
                     * examples:
                     * $item.body|htmlspecialchars              // escape html chars
                     * $item.body|htmlspecialchars|strtoupper   // escape html and uppercase result
                     * $item.created|date:%Y %M %j              // format date (created is a timestamp)
                     * $item.body|str_replace:cat:dog           // replace all "cat" with "dog"
                     * $item.body|str_replace:cat:dog:x:1       // replace one "cat" with "dog"
                     */
                    foreach ($exptks as $filterstr) {
                        $filter = explode(":", $filterstr);
                        $filtername = $filter[0];
                        unset($filter[0]);
                        $valkey = array_search("x", $filter);
                        if ($valkey === false) {
                            $filter[] = $val;
                        } else {
                            $filter[$valkey] = $val;
                        }
                        if (function_exists($filtername)) {
                            $val = call_user_func_array($filtername, $filter);
                        }
                    }
                    $s = str_replace($var, $val, $s);
                }
            }
        }

        return $s;
    }

    private function replace($s, $r)
    {
        return $this->replace_macros($s, $r);
    }

    // TemplateEngine interface

    public function replace_macros($s, $r)
    {
        $this->r = $r;

        $s = $this->_build_nodes($s);

        $s = preg_replace_callback('/\|\|([0-9]+)\|\|/', [$this, "_replcb_node"], $s);
        if ($s == null) {
            $this->_preg_error();
        }

        // remove comments block
        $s = preg_replace('/{#[^#]*#}/', "", $s);

        //$t2 = dba_timer();

        // replace strings recursively (limit to 10 loops)
        $os = "";
        $count = 0;
        while (($os !== $s) && $count < 10) {
            $os = $s;
            $count++;
            $s = $this->var_replace($s);
        }

        return $s;
    }

    public function get_template($file, $root = '')
    {
        $template_file = Theme::include($file, $root);
        if ($template_file) {
            $content = file_get_contents($template_file);
        }

        return $content;
    }
}


function template_escape($s)
{
    return str_replace(['$','{{'], ['!_Doll^Ars1Az_!','!_DoubLe^BraceS4Rw_!'], $s);
}

function template_unescape($s)
{
    return str_replace(['!_Doll^Ars1Az_!','!_DoubLe^BraceS4Rw_!'], ['$','{{'], $s);
}