Re: Ada DB bindings and APQ

[Brian May <bam@snoopy.apana.org.au>]

>>>>> "Georg" == Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de> writes:
  
    Georg> :> Example 26-3. Connect to SQLite on a Unix machine using options
    Georg> :> 
    Georg> :> sqlite:////full/unix/path/to/file.db?mode=0666
    Georg> : 
    Georg> : Not sure why there are so many leading slashes in this case.

    Georg> I think its because the database name is actually a file name?
    Georg> The example having 'hostspec:110//usr/db_file.db' may be similar.
    Georg> Not sure either.

I would speculate:

sqlite:// + nullhost + / + path

where path="/full/unix/path/to/file.db?mode=0666" maybe with the implication
that you could use:

sqlite:///file.db to refer to the database file in the current directory.

Seems kind of dodgy to me, but you don't want to have to use relative
paths for everything.

For reference, here is the code use for decoding these URLs in
PHP/PEAR. It was copied from /usr/share/php/DB.php on my computer. It
might be possible to rewrite this in Ada.

Also see documentation for rawurldecode at
<URL:http://au2.php.net/manual/en/function.rawurldecode.php>.
     
    // {{{ parseDSN()

    /**
     * Parse a data source name.
     *
     * Additional keys can be added by appending a URI query string to the
     * end of the DSN.
     *
     * The format of the supplied DSN is in its fullest form:
     * <code>
     *  phptype(dbsyntax)://username:password@protocol+hostspec/database?option=8&another=true
     * </code>
     *
     * Most variations are allowed:
     * <code>
     *  phptype://username:password@protocol+hostspec:110//usr/db_file.db?mode=0644
     *  phptype://username:password@hostspec/database_name
     *  phptype://username:password@hostspec
     *  phptype://username@hostspec
     *  phptype://hostspec/database
     *  phptype://hostspec
     *  phptype(dbsyntax)
     *  phptype
     * </code>
     *
     * @param string $dsn Data Source Name to be parsed
     *
     * @return array an associative array with the following keys:
     *  + phptype:  Database backend used in PHP (mysql, odbc etc.)
     *  + dbsyntax: Database used with regards to SQL syntax etc.
     *  + protocol: Communication protocol to use (tcp, unix etc.)
     *  + hostspec: Host specification (hostname[:port])
     *  + database: Database to use on the DBMS server
     *  + username: User name for login
     *  + password: Password for login
     *
     * @author Tomas V.V.Cox <cox@idecnet.com>
     */
    function parseDSN($dsn)
    {
        $parsed = array(
            'phptype'  => false,
            'dbsyntax' => false,
            'username' => false,
            'password' => false,
            'protocol' => false,
            'hostspec' => false,
            'port'     => false,
            'socket'   => false,
            'database' => false,
        );

        if (is_array($dsn)) {
            $dsn = array_merge($parsed, $dsn);
            if (!$dsn['dbsyntax']) {
                $dsn['dbsyntax'] = $dsn['phptype'];
            }
            return $dsn;
        }

        // Find phptype and dbsyntax
        if (($pos = strpos($dsn, '://')) !== false) {
            $str = substr($dsn, 0, $pos);
            $dsn = substr($dsn, $pos + 3);
        } else {
            $str = $dsn;
            $dsn = null;
        }

        // Get phptype and dbsyntax
        // $str => phptype(dbsyntax)
        if (preg_match('|^(.+?)\((.*?)\)$|', $str, $arr)) {
            $parsed['phptype']  = $arr[1];
            $parsed['dbsyntax'] = !$arr[2] ? $arr[1] : $arr[2];
        } else {
            $parsed['phptype']  = $str;
            $parsed['dbsyntax'] = $str;
        }

        if (!count($dsn)) {
            return $parsed;
        }

        // Get (if found): username and password
        // $dsn => username:password@protocol+hostspec/database
        if (($at = strrpos($dsn,'@')) !== false) {
            $str = substr($dsn, 0, $at);
            $dsn = substr($dsn, $at + 1);
            if (($pos = strpos($str, ':')) !== false) {
                $parsed['username'] = rawurldecode(substr($str, 0, $pos));
                $parsed['password'] = rawurldecode(substr($str, $pos + 1));
            } else {
                $parsed['username'] = rawurldecode($str);
            }
        }

        // Find protocol and hostspec

        // $dsn => proto(proto_opts)/database
        if (preg_match('|^([^(]+)\((.*?)\)/?(.*?)$|', $dsn, $match)) {
            $proto       = $match[1];
            $proto_opts  = $match[2] ? $match[2] : false;
            $dsn         = $match[3];

        // $dsn => protocol+hostspec/database (old format)
        } else {
            if (strpos($dsn, '+') !== false) {
                list($proto, $dsn) = explode('+', $dsn, 2);
            }
            if (strpos($dsn, '/') !== false) {
                list($proto_opts, $dsn) = explode('/', $dsn, 2);
            } else {
                $proto_opts = $dsn;
                $dsn = null;
            }
        }

        // process the different protocol options
        $parsed['protocol'] = (!empty($proto)) ? $proto : 'tcp';
        $proto_opts = rawurldecode($proto_opts);
        if ($parsed['protocol'] == 'tcp') {
            if (strpos($proto_opts, ':') !== false) {
                list($parsed['hostspec'], $parsed['port']) = explode(':', $proto_opts);
            } else {
                $parsed['hostspec'] = $proto_opts;
            }
        } elseif ($parsed['protocol'] == 'unix') {
            $parsed['socket'] = $proto_opts;
        }

        // Get dabase if any
        // $dsn => database
        if ($dsn) {
            // /database
            if (($pos = strpos($dsn, '?')) === false) {
                $parsed['database'] = $dsn;
            // /database?param1=value1&param2=value2
            } else {
                $parsed['database'] = substr($dsn, 0, $pos);
                $dsn = substr($dsn, $pos + 1);
                if (strpos($dsn, '&') !== false) {
                    $opts = explode('&', $dsn);
                } else { // database?param1=value1
                    $opts = array($dsn);
                }
                foreach ($opts as $opt) {
                    list($key, $value) = explode('=', $opt);
                    if (!isset($parsed[$key])) {
                        // don't allow params overwrite
                        $parsed[$key] = rawurldecode($value);
                    }
                }
            }
        }

        return $parsed;
    }

    // }}}

-- 
Brian May <bam@snoopy.apana.org.au>