HTMLPurifier_URI::validate PHP Method

    public function validate($config, $context)
    {
        // ABNF definitions from RFC 3986
        $chars_sub_delims = '!$&\'()*+,;=';
        $chars_gen_delims = ':/?#[]@';
        $chars_pchar = $chars_sub_delims . ':@';
        // validate host
        if (!is_null($this->host)) {
            $host_def = new HTMLPurifier_AttrDef_URI_Host();
            $this->host = $host_def->validate($this->host, $config, $context);
            if ($this->host === false) {
                $this->host = null;
            }
        }
        // validate scheme
        // NOTE: It's not appropriate to check whether or not this
        // scheme is in our registry, since a URIFilter may convert a
        // URI that we don't allow into one we do.  So instead, we just
        // check if the scheme can be dropped because there is no host
        // and it is our default scheme.
        if (!is_null($this->scheme) && is_null($this->host) || $this->host === '') {
            // support for relative paths is pretty abysmal when the
            // scheme is present, so axe it when possible
            $def = $config->getDefinition('URI');
            if ($def->defaultScheme === $this->scheme) {
                $this->scheme = null;
            }
        }
        // validate username
        if (!is_null($this->userinfo)) {
            $encoder = new HTMLPurifier_PercentEncoder($chars_sub_delims . ':');
            $this->userinfo = $encoder->encode($this->userinfo);
        }
        // validate port
        if (!is_null($this->port)) {
            if ($this->port < 1 || $this->port > 65535) {
                $this->port = null;
            }
        }
        // validate path
        $segments_encoder = new HTMLPurifier_PercentEncoder($chars_pchar . '/');
        if (!is_null($this->host)) {
            // this catches $this->host === ''
            // path-abempty (hier and relative)
            // http://www.example.com/my/path
            // //www.example.com/my/path (looks odd, but works, and
            //                            recognized by most browsers)
            // (this set is valid or invalid on a scheme by scheme
            // basis, so we'll deal with it later)
            // file:///my/path
            // ///my/path
            $this->path = $segments_encoder->encode($this->path);
        } elseif ($this->path !== '') {
            if ($this->path[0] === '/') {
                // path-absolute (hier and relative)
                // http:/my/path
                // /my/path
                if (strlen($this->path) >= 2 && $this->path[1] === '/') {
                    // This could happen if both the host gets stripped
                    // out
                    // http://my/path
                    // //my/path
                    $this->path = '';
                } else {
                    $this->path = $segments_encoder->encode($this->path);
                }
            } elseif (!is_null($this->scheme)) {
                // path-rootless (hier)
                // http:my/path
                // Short circuit evaluation means we don't need to check nz
                $this->path = $segments_encoder->encode($this->path);
            } else {
                // path-noscheme (relative)
                // my/path
                // (once again, not checking nz)
                $segment_nc_encoder = new HTMLPurifier_PercentEncoder($chars_sub_delims . '@');
                $c = strpos($this->path, '/');
                if ($c !== false) {
                    $this->path = $segment_nc_encoder->encode(substr($this->path, 0, $c)) . $segments_encoder->encode(substr($this->path, $c));
                } else {
                    $this->path = $segment_nc_encoder->encode($this->path);
                }
            }
        } else {
            // path-empty (hier and relative)
            $this->path = '';
            // just to be safe
        }
        // qf = query and fragment
        $qf_encoder = new HTMLPurifier_PercentEncoder($chars_pchar . '/?');
        if (!is_null($this->query)) {
            $this->query = $qf_encoder->encode($this->query);
        }
        if (!is_null($this->fragment)) {
            $this->fragment = $qf_encoder->encode($this->fragment);
        }
        return true;
    }