iterator.php

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<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Database
 *
 * @copyright   Copyright (C) 2005 - 2013 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

/**
 * Joomla Platform Database Driver Class
 *
 * @package     Joomla.Platform
 * @subpackage  Database
 * @since       12.1
 */
abstract class JDatabaseIterator implements Countable, Iterator
{
        /**
         * The database cursor.
         *
         * @var    mixed
         * @since  12.1
         */
        protected $cursor;

        /**
         * The class of object to create.
         *
         * @var    string
         * @since  12.1
         */
        protected $class;

        /**
         * The name of the column to use for the key of the database record.
         *
         * @var    mixed
         * @since  12.1
         */
        private $_column;

        /**
         * The current database record.
         *
         * @var    mixed
         * @since  12.1
         */
        private $_current;

        /**
         * A numeric or string key for the current database record.
         *
         * @var    scalar
         * @since  12.1
         */
        private $_key;

        /**
         * The number of fetched records.
         *
         * @var    integer
         * @since  12.1
         */
        private $_fetched = 0;

        /**
         * Database iterator constructor.
         *
         * @param   mixed   $cursor  The database cursor.
         * @param   string  $column  An option column to use as the iterator key.
         * @param   string  $class   The class of object that is returned.
         *
         * @throws  InvalidArgumentException
         */
        public function __construct($cursor, $column = null, $class = 'stdClass')
        {
                if (!class_exists($class))
                {
                        throw new InvalidArgumentException(sprintf('new %s(*%s*, cursor)', get_class($this), gettype($class)));
                }

                $this->cursor = $cursor;
                $this->class = $class;
                $this->_column = $column;
                $this->_fetched = 0;
                $this->next();
        }

        /**
         * Database iterator destructor.
         *
         * @since   12.1
         */
        public function __destruct()
        {
                if ($this->cursor)
                {
                        $this->freeResult($this->cursor);
                }
        }

        /**
         * The current element in the iterator.
         *
         * @return  object
         *
         * @see     Iterator::current()
         * @since   12.1
         */
        public function current()
        {
                return $this->_current;
        }

        /**
         * The key of the current element in the iterator.
         *
         * @return  scalar
         *
         * @see     Iterator::key()
         * @since   12.1
         */
        public function key()
        {
                return $this->_key;
        }

        /**
         * Moves forward to the next result from the SQL query.
         *
         * @return  void
         *
         * @see     Iterator::next()
         * @since   12.1
         */
        public function next()
        {
                // Set the default key as being the number of fetched object
                $this->_key = $this->_fetched;

                // Try to get an object
                $this->_current = $this->fetchObject();

                // If an object has been found
                if ($this->_current)
                {
                        // Set the key as being the indexed column (if it exists)
                        if (isset($this->_current->{$this->_column}))
                        {
                                $this->_key = $this->_current->{$this->_column};
                        }

                        // Update the number of fetched object
                        $this->_fetched++;
                }
        }

        /**
         * Rewinds the iterator.
         *
         * This iterator cannot be rewound.
         *
         * @return  void
         *
         * @see     Iterator::rewind()
         * @since   12.1
         */
        public function rewind()
        {
        }

        /**
         * Checks if the current position of the iterator is valid.
         *
         * @return  boolean
         *
         * @see     Iterator::valid()
         * @since   12.1
         */
        public function valid()
        {
                return (boolean) $this->_current;
        }

        /**
         * Method to fetch a row from the result set cursor as an object.
         *
         * @return  mixed  Either the next row from the result set or false if there are no more rows.
         *
         * @since   12.1
         */
        abstract protected function fetchObject();

        /**
         * Method to free up the memory used for the result set.
         *
         * @return  void
         *
         * @since   12.1
         */
        abstract protected function freeResult();
}