*      <li>
     *        <kbd>odbc</kbd> -> <samp>1/0</samp>
     *        (<kbd>SMALLINT</kbd>) [1]
     *      </li>
     *      <li>
     *        <kbd>pgsql</kbd> -> <samp>TRUE/FALSE</samp>
     *        (<kbd>BOOLEAN</kbd>)
     *      </li>
     *      <li>
     *        <kbd>sqlite</kbd> -> <samp>1/0</samp>
     *        (<kbd>INTEGER</kbd>)
     *      </li>
     *      <li>
     *        <kbd>sybase</kbd> -> <samp>1/0</samp>
     *        (<kbd>TINYINT(1)</kbd>)
     *      </li>
     *    </ul>
     *    [1] Accommodate the lowest common denominator because not all
     *    versions of have <kbd>BOOLEAN</kbd>.
     *  </li>
     *  <li>
     *    other (including strings and numeric strings) ->
     *    the data with single quotes escaped by preceeding
     *    single quotes, backslashes are escaped by preceeding
     *    backslashes, then the whole string is encapsulated
     *    between single quotes
     *  </li>
     * </ul>
     *
     * @see DB_common::escapeSimple()
     * @since Method available since Release 1.6.0
     */
    function quoteSmart($in)
    {
        if (is_int($in) || is_double($in)) {
            return $in;
        } elseif (is_bool($in)) {
            return $in ? 1 : 0;
        } elseif (is_null($in)) {
            return 'NULL';
        } else {
            return "'" . $this->escapeSimple($in) . "'";
        }
    }

    // }}}
    // {{{ escapeSimple()

    /**
     * Escapes a string according to the current DBMS's standards
     *
     * In SQLite, this makes things safe for inserts/updates, but may
     * cause problems when performing text comparisons against columns
     * containing binary data. See the
     * {@link http://php.net/sqlite_escape_string PHP manual} for more info.
     *
     * @param string $str  the string to be escaped
     *
     * @return string  the escaped string
     *
     * @see DB_common::quoteSmart()
     * @since Method available since Release 1.6.0
     */
    function escapeSimple($str)
    {
        return str_replace("'", "''", $str);
    }

    // }}}
    // {{{ provides()

    /**
     * Tells whether the present driver supports a given feature
     *
     * @param string $feature  the feature you're curious about
     *
     * @return bool  whether this driver supports $feature
     */
    function provides($feature)
    {
        return $this->features[$feature];
    }

    // }}}
    // {{{ setFetchMode()

    /**
     * Sets the fetch mode that should be used by default for query results
     *
     * @param integer $fetchmode    DB_FETCHMODE_ORDERED, DB_FETCHMODE_ASSOC
     *                               or DB_FETCHMODE_OBJECT
     * @param string $object_class  the class name of the object to be returned
     *                               by the fetch methods when the
     *                               DB_FETCHMODE_OBJECT mode is selected.
     *                               If no class is specified by default a cast
     *                               to object from the assoc array row will be
     *                               done.  There is also the posibility to use
     *                               and extend the 'DB_row' class.
     *
     * @see DB_FETCHMODE_ORDERED, DB_FETCHMODE_ASSOC, DB_FETCHMODE_OBJECT
     */
    function setFetchMode($fetchmode, $object_class = 'stdClass')
    {
        switch ($fetchmode) {
            case DB_FETCHMODE_OBJECT:
                $this->fetchmode_object_class = $object_class;
            case DB_FETCHMODE_ORDERED:
            case DB_FETCHMODE_ASSOC:
                $this->fetchmode = $fetchmode;
                break;
            default:
                return $this->raiseError('invalid fetchmode mode');
        }
    }

    // }}}
    // {{{ setOption()

    /**
     * Sets run-time configuration options for PEAR DB
     *
     * Options, their data types, default values and description:
     * <ul>
     * <li>
     * <var>autofree</var> <kbd>boolean</kbd> = <samp>false</samp>
     *      <br />should results be freed automatically when there are no
     *            more rows?
     * </li><li>
     * <var>result_buffering</var> <kbd>integer</kbd> = <samp>500</samp>
     *      <br />how many rows of the result set should be buffered?
     *      <br />In mysql: mysql_unbuffered_query() is used instead of
     *            mysql_query() if this value is 0.  (Release 1.7.0)
     *      <br />In oci8: this value is passed to ocisetprefetch().
     *            (Release 1.7.0)
     * </li><li>
     * <var>debug</var> <kbd>integer</kbd> = <samp>0</samp>
     *      <br />debug level
     * </li><li>
     * <var>persistent</var> <kbd>boolean</kbd> = <samp>false</samp>
     *      <br />should the connection be persistent?
     * </li><li>
     * <var>portability</var> <kbd>integer</kbd> = <samp>DB_PORTABILITY_NONE</samp>
     *      <br />portability mode constant (see below)
     * </li><li>
     * <var>seqname_format</var> <kbd>string</kbd> = <samp>%s_seq</samp>
     *      <br />the sprintf() format string used on sequence names.  This
     *            format is applied to sequence names passed to
     *            createSequence(), nextID() and dropSequence().
     * </li><li>
     * <var>ssl</var> <kbd>boolean</kbd> = <samp>false</samp>
     *      <br />use ssl to connect?
     * </li>
     * </ul>
     *
     * -----------------------------------------
     *
     * PORTABILITY MODES
     *
     * These modes are bitwised, so they can be combined using <kbd>|</kbd>
     * and removed using <kbd>^</kbd>.  See the examples section below on how
     * to do this.
     *
     * <samp>DB_PORTABILITY_NONE</samp>
     * turn off all portability features
     *
     * This mode gets automatically turned on if the deprecated
     * <var>optimize</var> option gets set to <samp>performance</samp>.
     *
     *
     * <samp>DB_PORTABILITY_LOWERCASE</samp>
     * convert names of tables and fields to lower case when using
     * <kbd>get*()</kbd>, <kbd>fetch*()</kbd> and <kbd>tableInfo()</kbd>
     *
     * This mode gets automatically turned on in the following databases
     * if the deprecated option <var>optimize</var> gets set to
     * <samp>portability</samp>:
     * + oci8
     *
     *
     * <samp>DB_PORTABILITY_RTRIM</samp>
     * right trim the data output by <kbd>get*()</kbd> <kbd>fetch*()</kbd>
     *
     *
     * <samp>DB_PORTABILITY_DELETE_COUNT</samp>
     * force reporting the number of rows deleted
     *
     * Some DBMS's don't count the number of rows deleted when performing
     * simple <kbd>DELETE FROM tablename</kbd> queries.  This portability
     * mode tricks such DBMS's into telling the count by adding
     * <samp>WHERE 1=1</samp> to the end of <kbd>DELETE</kbd> queries.
     *
     * This mode gets automatically turned on in the following databases
     * if the deprecated option <var>optimize</var> gets set to
     * <samp>portability</samp>:
     * + fbsql
     * + mysql
     * + mysqli
     * + sqlite
     *
     *
     * <samp>DB_PORTABILITY_NUMROWS</samp>
     * enable hack that makes <kbd>numRows()</kbd> work in Oracle
     *
     * This mode gets automatically turned on in the following databases
     * if the deprecated option <var>optimize</var> gets set to
     * <samp>portability</samp>:
     * + oci8
     *
     *
     * <samp>DB_PORTABILITY_ERRORS</samp>
     * makes certain error messages in certain drivers compatible
     * with those from other DBMS's
     *
     * + mysql, mysqli:  change unique/primary key constraints
     *   DB_ERROR_ALREADY_EXISTS -> DB_ERROR_CONSTRAINT
     *
     * + odbc(access):  MS's ODBC driver reports 'no such field' as code
     *   07001, which means 'too few parameters.'  When this option is on
     *   that code gets mapped to DB_ERROR_NOSUCHFIELD.
     *   DB_ERROR_MISMATCH -> DB_ERROR_NOSUCHFIELD
     *
     * <samp>DB_PORTABILITY_NULL_TO_EMPTY</samp>
     * convert null values to empty strings in data output by get*() and
     * fetch*().  Needed because Oracle considers empty strings to be null,
     * while most other DBMS's know the difference between empty and null.
     *
     *
     * <samp>DB_PORTABILITY_ALL</samp>
     * turn on all portability features
     *
     * -----------------------------------------
     *
     * Example 1. Simple setOption() example
     * <code>
     * $db->setOption('autofree', true);
     * </code>
     *
     * Example 2. Portability for lowercasing and trimming
     * <code>
     * $db->setOption('portability',
     *                 DB_PORTABILITY_LOWERCASE | DB_PORTABILITY_RTRIM);
     * </code>
     *
     * Example 3. All portability options except trimming
     * <code>
     * $db->setOption('portability',
     *                 DB_PORTABILITY_ALL ^ DB_PORTABILITY_RTRIM);
     * </code>
     *
     * @param string $option option name
     * @param mixed  $value value for the option
     *
     * @return int  DB_OK on success.  A DB_Error object on failure.
     *
     * @see DB_common::$options
     */
    function setOption($option, $value)
    {
        if (isset($this->options[$option])) {
            $this->options[$option] = $value;

            /*
             * Backwards compatibility check for the deprecated 'optimize'
             * option.  Done here in case settings change after connecting.
             */
            if ($option == 'optimize') {
                if ($value == 'portability') {
                    switch ($this->phptype) {
                        case 'oci8':
                            $this->options['portability'] =
                                    DB_PORTABILITY_LOWERCASE |
                                    DB_PORTABILITY_NUMROWS;
                            break;
                        case 'fbsql':
                        case 'mysql':
                        case 'mysqli':
                        case 'sqlite':
                            $this->options['portability'] =
                                    DB_PORTABILITY_DELETE_COUNT;
                            break;
                    }
                } else {
                    $this->options['portability'] = DB_PORTABILITY_NONE;
                }
            }

            return DB_OK;
        }
        return $this->raiseError("unknown option $option");
    }

    // }}}
    // {{{ getOption()

    /**
     * Returns the value of an option
     *
     * @param string $option  the option name you're curious about
     *
     * @return mixed  the option's value
     */
    function getOption($option)
    {
        if (isset($this->options[$option])) {
            return $this->options[$option];
        }
        return $this->raiseError("unknown option $option");
    }

    // }}}
    // {{{ prepare()

    /**
     * Prepares a query for multiple execution with execute()
     *
     * Creates a query that can be run multiple times.  Each time it is run,
     * the placeholders, if any, will be replaced by the contents of
     * execute()'s $data argument.
     *
     * Three types of placeholders can be used:
     *   + <kbd>?</kbd>  scalar value (i.e. strings, integers).  The system
     *                   will automatically quote and escape the data.
     *   + <kbd>!</kbd>  value is inserted 'as is'
     *   + <kbd>&</kbd>  requires a file name.  The file's contents get
     *                   inserted into the query (i.e. saving binary
     *                   data in a db)
     *
     * Example 1.
     * <code>
     * $sth = $db->prepare('INSERT INTO tbl (a, b, c) VALUES (?, !, &)');
     * $data = array(
     *     "John's text",
     *     "'it''s good'",
     *     'filename.txt'
     * );
     * $res = $db->execute($sth, $data);
     * </code>
     *
     * Use backslashes to escape placeholder characters if you don't want
     * them to be interpreted as placeholders:
     * <pre>
     *    "UPDATE foo SET col=? WHERE col='over \& under'"
     * </pre>
     *
     * With some database backends, this is emulated.
     *
     * {@internal ibase and oci8 have their own prepare() methods.}}
     *
     * @param string $query  the query to be prepared
     *
     * @return mixed  DB statement resource on success. A DB_Error object
     *                 on failure.
     *
     * @see DB_common::execute()
     */
    function prepare($query)
    {
        $tokens   = preg_split('/((?<!\\\)[&?!])/', $query, -1,
                               PREG_SPLIT_DELIM_CAPTURE);
        $token     = 0;
        $types     = array();
        $newtokens = array();

        foreach ($tokens as $val) {
            switch ($val) {
                case '?':
                    $types[$token++] = DB_PARAM_SCALAR;
                    break;
                case '&':
                    $types[$token++] = DB_PARAM_OPAQUE;
                    break;
                case '!':
                    $types[$token++] = DB_PARAM_MISC;
                    break;
                default:
                    $newtokens[] = preg_replace('/\\\([&?!])/', "\\1", $val);
            }
        }

        $this->prepare_tokens[] = &$newtokens;
        end($this->prepare_tokens);

        $k = key($this->prepare_tokens);
        $this->prepare_types[$k] = $types;
        $this->prepared_queries[$k] = implode(' ', $newtokens);

        return $k;
    }

    // }}}
    // {{{ autoPrepare()