books/scripts/books_xml.php

<?php
#*****************************************************************************
#
# news.php
#
# Author: 		Wayne Beaton
# Date:			2005-11-07
#
# Description: This file contains the code required to read the RSS file
# into an object representation.  
#
#****************************************************************************

function get_library() {
	return get_books_from_file($_SERVER['DOCUMENT_ROOT'] . "/community/books/books.xml");
//	$xml = simplexml_load_file($_SERVER['DOCUMENT_ROOT'] . "/community/books/books.xml");
//	return xml_to_library($xml);
}

/*
 * This method extracts the RSS information from the file with the
 * given name.
 */
function &get_books_from_file($file_name) {
	// PHP 5: simplexml_load_file($newsfile);
	return parse_books_xml_file($file_name);
}
	
/*
 * The rest of the code in this file is concerned with reading XML
 * into an object format. Once we update to PHP 5, we can get rid of
 * all of this junk and just use the simpleXML apis.
 */

/*
 * This function does the actual work of parsing the RSS
 * file into an object representation. We use a SAX parser
 * to do this.
 * 
 * Note that this function is intended to be used with relatively
 * short files (the entire file contents are loaded into memory).
 * If the RSS files start to get too large, this method will need
 * to be updated.
 */
function &parse_books_xml_file($file_name) {	
	global $handler;

	$handler->reset();

	// Read the entire file contents in to memory.
	// If file sizes get too large, we'll have to be smarter here.
	$file = fopen($file_name, "r");
	$xml = fread($file, filesize($file_name));
	fclose($file);

	$parser = xml_parser_create();
	xml_set_element_handler($parser, 'startHandler', 'endHandler');
	xml_set_character_data_handler($parser, 'dataHandler');
	xml_parse($parser, $xml);
	
	return $handler->library;
}

/*
 * The $handler variable is global. It manages all the call backs
 * that come (indirectly) from the SAX parser.
 */
$handler = new XmlHandler();

/*
 * SAX parser callback method to handle the start of an element.
 * This method just defers to the global handler to do the actual
 * work.
 */
function startHandler($parser, $name, $attributes) {
	global $handler;
	$handler->start($name, $attributes);
}

/*
 * SAX parser callback method to handle the text for an element.
 * This method just defers to the global handler to do the actual
 * work.
 */
function dataHandler($parser, $data) {
	global $handler;
	$handler->data($data);
}

/*
 * SAX parser callback method to handle the end of an element.
 * This method just defers to the global handler to do the actual
 * work.
 */
function endHandler($parser, $name) {
	global $handler;
	$handler->end($name);
}

/*
 * The XmlHandler class is the focal point of the SAX parser callbacks.
 * It keeps track of a stack of element handlers. The element handlers
 * are used to handle whatever elements come in.
 */
class XmlHandler {
	var $library;
	var $stack;

	/*
	 * This method resets the handler so that it is ready to parse
	 * something. Effectively, this cleans up a potentially dirty handler.
	 */
	function reset() {
		$this->library = new Library();
		$this->stack = array(new LibraryHandler($this->library));
	}
	
	/*
	 * Handle the start callback. Here, we get the current element handler
	 * from the top of the stack and ask it what to do. The element handler
	 * is asked to provide a new handler to handle the new element. That new
	 * handler is put on the top of the stack and will handle all future
	 * callbacks until it is removed (by the end method).
	 */
	function start($name, $attributes) {
		$handler =& array_last($this->stack);
		$next =& $handler->get_next($name, $attributes);
		array_push($this->stack, $next);
	}
	
	/*
	 * Data has been encountered, send the data to the current element handler
	 * to sort out what needs to be done.
	 */
	function data($data) {
		$handler =& array_last($this->stack);
		$handler->data($data);
	}

	/*
	 * The end of an element has occurred. Pop the current element handler
	 * from the top of the stack and tell it that it's work is done.
	 */
	function end($name) {			
		$handler =& array_pop($this->stack);
		$handler->end($name);
	}
}

/*
 * The FeedHandler class takes care of the root element in the file.
 */
class LibraryHandler {
	var $library;
	
	function LibraryHandler(&$library) {
		$this->library =& $library;
	}
	
	/*
	 * Return an appropriate handler to deal with an element named $name.
	 * At this point, we only expect to see an <rss> element.
	 */
	function &get_next($name, $attributes) {
		if (strcasecmp($name, "books") == 0) {
			return new BooksHandler($this->library);
		} else {
			return new DoNothingHandler();
		}
	}
	
	/*
	 * Ignore data for this element.
	 */
	function data($data) {}
}


class BooksHandler {
	var $library;
	
	function BooksHandler(&$library) {
		$this->library =& $library;
	}
	
	function data($data) {}
	
	/*
	 * Return an appropriate handler to deal with an element named $name.
	 * At this point, we only expect to see an <channel> element.
	 */
	function &get_next($name, $attributes) {
		if (strcasecmp($name, "book") == 0) {
			return new BookHandler($this->library);
		}
	}
	
	/*
	 * Ignore data for this element.
	 */
	function end($name) {}
}

class BookHandler {
	var $library;
	var $book;
	
	function BookHandler(&$library) {
		$this->library =& $library;
		$this->book = new Book();
	}
	
	function data($data) {}
	
	function &get_next($name, $attributes) {
		if (strcasecmp($name, "title") == 0) {
			return new SimplePropertyHandler($this->book, "title");
		} else if (strcasecmp($name, "author") == 0) {
			return new AuthorHandler($this->book);
		} else if (strcasecmp($name, "url") == 0) {
			return new SimplePropertyHandler($this->book, "url");
		} else if (strcasecmp($name, "date") == 0) {
			return new DateHandler($this->book, "date");
		} else if (strcasecmp($name, "description") == 0) {
			return new SimplePropertyHandler($this->book, "description");
		} else {
			return new DoNothingHandler();
		}
	}
	
	function end($name) {
		$this->library->add_book($this->book);
	}
}

class SimpleTextHandler {
	var $text;
	
	function &get_next($name, $attributes) {
		return new DoNothingHandler();
	}
	
	function data($data) {
		$this->text .= $data;
	}
	
	function end($name) {
	}
}

class SimplePropertyHandler extends SimpleTextHandler {
	var $owner;
	var $property;
	
	function SimplePropertyHandler(&$owner, $property) {
		
		$this->owner =& $owner;
		$this->property = $property;
	}
		
	function end($name) {
		$this->set_property_value($this->text);
	}
	
	function set_property_value(&$value) {
		$property = $this->property;
		$this->owner->$property = $value;
	}
}

class DateHandler extends SimplePropertyHandler {
	function end($name) {
		$this->set_property_value(strtotime($this->text));
	}
}

class AuthorHandler extends SimpleTextHandler {
	var $book;
	
	function AuthorHandler(&$book) {
		$this->book =& $book;
	}
	
	function end($name) {
		$this->book->add_author($this->text);
	}
}

class DoNothingHandler {
	
	function DoNothingHandler() {
	}
	
	function data($data) {
	}
	
	function end($name) {
	}
	
	function &get_next($name, $attributes) {
		return $this;
	}
}


function &array_last(&$array) {
	return $array[count($array)-1];
}

//
//function xml_to_library(&$xml) {
//	$library = new Library();
//	foreach ($xml->book as $book) {
//		$library->add_book(xml_to_book($book));
//	}
//	return $library;
//}
//
//function xml_to_book(&$xml) {
//	$book = new Book();
//	$book->title = $xml->title;
//	foreach ($xml->author as $author) {
//		$book->add_author($author);
//	}
//	$date = $xml->date;
//	if (strlen($date) > 0) {
//		$book->date = strtotime($date);
//	}
//	$book->url = $xml->url;
//	$book->description = $xml->description;
//	
//	return $book;
//}
//	
?>