Reader.php

<?php

/**
 * The Reader class file.
 *
 * This file is part of PicaReader.
 *
 * PicaReader is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * PicaReader is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with PicaReader.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @package   PicaReader
 * @author    David Maus <maus@hab.de>
 * @copyright Copyright (c) 2012, 2013 by Herzog August Bibliothek Wolfenbüttel
 * @license   http://www.gnu.org/licenses/gpl.html GNU General Public License v3
 */

namespace HAB\Pica\Reader;

use Exception;
use RuntimeException;

use HAB\Pica\Record\Record;

abstract class Reader
{

    /**
     * TRUE if the reader was opened with input data.
     *
     * @var boolean
     */
    protected $_isOpen = false;

    /**
     * Filter function or NULL if none set.
     *
     * @see Reader::setFilter()
     *
     * @var callback|null
     */
    protected $_filter = null;

    /**
     * Constructor.
     *
     * @return void
     */
    public function __construct ()
    {}

    /**
     * Open the reader with input data.
     *
     * @return void
     */
    public function open ($data)
    {
        if ($this->isOpen()) {
            $this->close();
        }
        $this->_isOpen = true;
    }

    /**
     * Return next record in input data or FALSE if no more records.
     *
     * This function uses the Record::factory() method to create a record and
     * applies a possible filter function to the input data.
     *
     * @see Reader::setFilter()
     * @see Record::factory()
     *
     * @throws RuntimeException Error creating a record instance via factory function
     * @return Record|false
     */
    public function read ()
    {
        $record = $this->next();
        if (is_array($record)) {
            $record = $this->applyFilter($record);
            if (is_array($record)) {
                try {
                    return Record::factory($record);
                } catch (Exception $e) {
                    throw new RuntimeException("Error creating record instance in Record::factory()", -1, $e);
                }
            }
        }
        return false;
    }

    /**
     * Set a filter function.
     *
     * A filter function is every valid callback function that takes the array
     * representation of a record as only argument and returns a possibly
     * modifed array or false to skip the record.
     *
     * @param  callback $filter Filter function
     * @return array|false
     */
    public function setFilter ($filter)
    {
        $this->_filter = $filter;
    }

    /**
     * Return current filter function.
     *
     * @return callback|null
     */
    public function getFilter ()
    {
        return $this->_filter;
    }

    /**
     * Unset the filter function.
     *
     * @return void
     */
    public function unsetFilter ()
    {
        $this->_filter = null;
    }

    /**
     * Close the reader.
     *
     * @return void
     */
    public function close ()
    {
        $this->_isOpen = false;
    }

    /**
     * Return true if the reader is open.
     *
     * @return boolean
     */
    public function isOpen ()
    {
        return $this->_isOpen;
    }


    /**
     * Read the next record in input data.
     *
     * Returns array representation of the record or false if no more records.
     *
     * @return array|false
     */
    abstract protected function next ();

    /**
     * Return filtered record.
     *
     * Applies the filter function to the array representation of a record.
     *
     * @param  array $record Array representation of record
     * @return array|false
     */
    protected function applyFilter (array $record)
    {
        $filter = $this->getFilter();
        if ($filter) {
            return call_user_func($filter, $record);
        } else {
            return $record;
        }
    }
}