moodle/rss/class.RSS.php

<?php //$Id$

/**
 * Project:     MagpieRSS: a simple RSS integration tool
 * File:        rss_parse.inc includes code for parsing
 *              RSS, and returning an RSS object
 * Author:      Kellan Elliott-McCrea <kellan@protest.net>
 * Version:     0.51
 * License:     GPL
 *
 * The lastest version of MagpieRSS can be obtained from:
 * http://magpierss.sourceforge.net
 *
 * For questions, help, comments, discussion, etc., please join the
 * Magpie mailing list:
 * magpierss-general@lists.sourceforge.net
 *
 */
 

/**
 * NOTES ON RSS PARSING PHILOSOPHY (moderately important):
 * MagpieRSS parse all versions of RSS with a few limitation (mod_content, and
 * mod_taxonomy support is shaky) into a simple object, with 2 fields, 
 * the hash 'channel', and the array 'items'.
 *
 * MagpieRSS is a forgiving and inclusive parser.  It currently makes no
 * attempt to enforce the validity on an RSS feed.  It will include any
 * properly formatted tags it finds, allowing to you to mix RSS 0.93, with RSS
 * 1.0, with tags or your own imagining.  This sort of witches brew is a bad
 * bad idea!  But Magpie is less pendantic then I am.
 *
 * RSS validators are readily available on the web at:
 * http://feeds.archive.org/validator/
 * http://www.ldodds.com/rss_validator/1.0/validator.html
 *
 */

/*
 * EXAMPLE PARSE RESULTS:
 *
 * Magpie tries to parse RSS into ease to use PHP datastructures.
 *
 * For example, Magpie on encountering RSS 1.0 item entry:
 *
 * <item rdf:about="http://protest.net/NorthEast/calendrome.cgi?span=event&#38;ID=210257">
 * <title>Weekly Peace Vigil</title>
 * <link>http://protest.net/NorthEast/calendrome.cgi?span=event&#38;ID=210257</link>
 * <description>Wear a white ribbon</description>
 * <dc:subject>Peace</dc:subject>
 * <ev:startdate>2002-06-01T11:00:00</ev:startdate>
 * <ev:location>Northampton, MA</ev:location>
 * <ev:enddate>2002-06-01T12:00:00</ev:enddate>
 * <ev:type>Protest</ev:type>
 * </item>
 * 
 * Would transform it into the following associative array, and push it
 * onto the array $rss-items
 *
 * array(
 *  title => 'Weekly Peace Vigil',
 *  link =>
 *  'http://protest.net/NorthEast/calendrome.cgi?span=event&#38;ID=210257',
 *  description => 'Wear a white ribbon',
 *  dc => array (
 *          subject => 'Peace'
 *      ),
 *  ev => array (
 *      startdate => '2002-06-01T11:00:00',
 *      enddate => '2002-06-01T12:00:00',
 *      type => 'Protest',
 *      location => 'Northampton, MA'
 *  )
 * )
 *
 */

class MagpieRSS {
    /*
     * Hybrid parser, and object.  (probably a bad idea! :)
     *
     * Useage Example:
     *
     * $some_rss = "<?xml version="1.0"......
     *
     * $rss = new MagpieRSS( $some_rss );
     *
     * // print rss chanel title
     * echo $rss->channel['title'];
     *
     * // print the title of each item
     * foreach ($rss->items as $item ) {
     *	  echo $item[title];
     * }
     *
     * see rss_fetch.inc for a simpler interface
     */
     
    var $parser;
    
    var $current_item   = array();	// item currently being parsed
    var $items          = array();	// collection of parsed items
    var $channel        = array();	// hash of channel fields
    var $textinput      = array();
    var $image          = array();
    
    var $parent_field   = array('RDF');
    var $current_field  = '';
    var $current_namespace  = false;
    
    var $ERROR = "";
    
    /*======================================================================*\
    Function: MagpieRSS
    Purpose:  Constructor, sets up XML parser,parses source,
              and populates object.. 
    Input:	  String containing the RSS to be parsed
    \*======================================================================*/
    function MagpieRSS ($source) {
        
        # if PHP xml isn't compiled in, die
        #
        if (!function_exists('xml_parser_create')) {
            $this->error( "Failed to load PHP's XML Extension. " . 
                          "http://www.php.net/manual/en/ref.xml.php",
                           E_USER_ERROR );
        }
        
        $parser = @xml_parser_create();
        
        if (!is_resource($parser))
        {
            $this->error( "Failed to create an instance of PHP's XML parser. " .
                          "http://www.php.net/manual/en/ref.xml.php",
                          E_USER_ERROR );
        }
    
        
        $this->parser = $parser;
        
        # pass in parser, and a reference to this object
        # setup handlers
        #
        xml_set_object( $this->parser, $this );
        xml_set_element_handler($this->parser, 'start_element', 'end_element');
        xml_set_character_data_handler( $this->parser, 'cdata' ); 
    
        
        $status = xml_parse( $this->parser, $source );
        
        if (! $status ) {
            $errorcode = xml_get_error_code( $this->parser );
            if ( $errorcode != XML_ERROR_NONE ) {
                $xml_error = xml_error_string( $errorcode );
                $error_line = xml_get_current_line_number($this->parser);
                $error_col = xml_get_current_column_number($this->parser);
                $errormsg = "$xml_error at line $error_line, column $error_col";
    
                $this->error( $errormsg );
            }
        }
        
        xml_parser_free( $this->parser );
    }
    
    function start_element ($p, $element, &$attrs) {
        $element    = strtolower( $element );
        # check for a namespace, and split if found
        #
        $namespace	= false;
        if ( strpos( $element, ':' ) ) {
            list($namespace, $element) = split( ':', $element, 2); 
        }
        $this->current_field = $element;
        if ( $namespace and $namespace != 'rdf' ) {
            $this->current_namespace = $namespace;
        }
        
        if ( $element == 'channel' ) {
            array_unshift( $this->parent_field, 'channel' );
        }
        elseif ( $element == 'items' ) {
            array_unshift( $this->parent_field, 'items' );
        }
        elseif ( $element == 'item' ) {
            array_unshift( $this->parent_field, 'item' );
        }
        elseif ( $element == 'textinput' ) {
            array_unshift( $this->parent_field, 'textinput' );
        }
        elseif ( $element == 'image' ) {
            array_unshift( $this->parent_field, 'image' );
        }
        
    }
    
    function end_element ($p, $element) {
        $element = strtolower($element);
                            
        if ( $element == 'item' ) {	
            $this->items[] = $this->current_item;
            $this->current_item = array();
            array_shift( $this->parent_field );
        }
        elseif ( $element == 'channel' or $element == 'items' or 
                 $element == 'textinput' or $element == 'image' ) {
            array_shift( $this->parent_field );
        }
        
        $this->current_field = '';
        $this->current_namespace = false;
    }
    
    function cdata ($p, $text) {
        # skip item, channel, items first time we see them
        #
        if ( $this->parent_field[0] == $this->current_field or
             ! $this->current_field ) {
            return;
        }
        elseif ( $this->parent_field[0] == 'channel') {
            if ( $this->current_namespace ) {
                $this->append(
                    $this->channel[ $this->current_namespace ][ $this->current_field ],
                    $text);
            }
            else {
                $this->append($this->channel[ $this->current_field ], $text);
            }
        
        }
        elseif ( $this->parent_field[0] == 'item' ) {
            if ( $this->current_namespace ) {
                $this->append(
                    $this->current_item[ $this->current_namespace ][$this->current_field ],
                    $text);
            }
            else {
                $this->append(
                    $this->current_item[ $this->current_field ],
                    $text );
            }
        }
        elseif ( $this->parent_field[0] == 'textinput' ) {
            if ( $this->current_namespace ) {
                $this->append(
                    $this->textinput[ $this->current_namespace ][ $this->current_field ],
                     $text );
            }
            else {
                $this->append(
                    $this->textinput[ $this->current_field ],
                    $text );
            }
        }
        elseif ( $this->parent_field[0] == 'image' ) {
            if ( $this->current_namespace ) {
                $this->append(
                    $this->image[ $this->current_namespace ][ $this->current_field ],
                    $text );
            }
            else {
                $this->append(
                    $this->image[ $this->current_field ],
                    $text );
            }
        }
    }
    
    function append (&$str1, $str2="") {
        if (!isset($str1) ) {
            $str1="";
        }
        $str1 .= $str2;
    }
    
    function error ($errormsg, $lvl=E_USER_WARNING) {
        // append PHP's error message if track_errors enabled
        if ( isset($php_errormsg) ) {
            $errormsg .= " ($php_errormsg)";
        }
        $this->ERROR = $errormsg;
        //if ( MAGPIE_DEBUG ) {
        //	trigger_error( $errormsg, $lvl);		
        //}
        //else {
            error_log( $errormsg, 0);
        //}
    }
        
    
    /*======================================================================*\
    EVERYTHING BELOW HERE IS FOR DEBUGGING PURPOSES
    \*======================================================================*/
    function show_list () {
        echo "<ol>\n";
        foreach ($this->items as $item) {
            echo "<li>", $this->show_item( $item );
        }
        echo "</ol>";
    }
    
    function show_channel () {
        echo "channel:<br>";
        echo "<ul>";
        while ( list($key, $value) = each( $this->channel ) ) {
            echo "<li> $key: $value";
        }
        echo "</ul>";
    }
    
    function show_item ($item) {
        echo "item: $item[title]";
        echo "<ul>";
        while ( list($key, $value) = each($item) ) {
            if ( is_array($value) ) {
                echo "<br><b>$key</b>";
                echo "<ul>";
                while ( list( $ns_key, $ns_value) = each( $value ) ) {
                    echo "<li>$ns_key: $ns_value";
                }
                echo "</ul>";
            }
            else {
                echo "<li> $key: $value";
            }
        }
        echo "</ul>";
    }
    
    /*======================================================================*\
    END DEBUGGING FUNCTIONS	
    \*======================================================================*/
    
} # end class RSS
?>