framework/web/UrlRule.php
private function preparePattern()
    {
        $this->pattern = $this->trimSlashes($this->pattern);
        $this->route = trim($this->route, '/');

        if ($this->host !== null) {
            $this->host = rtrim($this->host, '/');
            $this->pattern = rtrim($this->host . '/' . $this->pattern, '/');
        } elseif ($this->pattern === '') {
            $this->_template = '';
            $this->pattern = '#^$#u';

            return;
        } elseif (($pos = strpos($this->pattern, '://')) !== false) {
            if (($pos2 = strpos($this->pattern, '/', $pos + 3)) !== false) {
                $this->host = substr($this->pattern, 0, $pos2);
            } else {
                $this->host = $this->pattern;
            }
        } elseif (strncmp($this->pattern, '//', 2) === 0) {
            if (($pos2 = strpos($this->pattern, '/', 2)) !== false) {
                $this->host = substr($this->pattern, 0, $pos2);
            } else {
                $this->host = $this->pattern;
            }
        } else {
            $this->pattern = '/' . $this->pattern . '/';
        }

        if (strpos($this->route, '<') !== false && preg_match_all('/<([\w._-]+)>/', $this->route, $matches)) {
            foreach ($matches[1] as $name) {
                $this->_routeParams[$name] = "<$name>";
            }
        }

        $this->translatePattern(true);
    }
private function preparePattern()
    {
        $this->pattern = $this->trimSlashes($this->pattern);
        $this->route = trim($this->route, '/');

        if ($this->host !== null) {
            $this->host = rtrim($this->host, '/');
            $this->pattern = rtrim($this->host . '/' . $this->pattern, '/');
        } elseif ($this->pattern === '') {
            $this->_template = '';
            $this->pattern = '#^$#u';

            return;
        } elseif (($pos = strpos($this->pattern, '://')) !== false) {
            if (($pos2 = strpos($this->pattern, '/', $pos + 3)) !== false) {
                $this->host = substr($this->pattern, 0, $pos2);
            } else {
                $this->host = $this->pattern;
            }
        } elseif (strncmp($this->pattern, '//', 2) === 0) {
            if (($pos2 = strpos($this->pattern, '/', 2)) !== false) {
                $this->host = substr($this->pattern, 0, $pos2);
            } else {
                $this->host = $this->pattern;
            }
        } else {
            $this->pattern = '/' . $this->pattern . '/';
        }

        if (strpos($this->route, '<') !== false && preg_match_all('/<([\w._-]+)>/', $this->route, $matches)) {
            foreach ($matches[1] as $name) {
                $this->_routeParams[$name] = "<$name>";
            }
        }

        $this->translatePattern(true);
    }
Process [[$pattern]] on rule initialization.