lib/RssWriter.php

   1 <?php rcs_id('$Id: RssWriter.php,v 1.12 2005-07-24 09:52:59 rurban Exp $');
   2 /*
   3  * Code for creating RSS 1.0.
   4  */
   5
   6 // Encoding for RSS output.
   7 if (!defined('RSS_ENCODING'))
   8   define('RSS_ENCODING', $GLOBALS['charset']);
   9
  10 /**
  11  * A class for writing RSS 1.0.
  12  *
  13  * @see http://purl.org/rss/1.0/spec,
  14  *      http://www.usemod.com/cgi-bin/mb.pl?ModWiki
  15  */
  16 class RssWriter extends XmlElement
  17 {
  18     function RssWriter () {
  19         $this->XmlElement('rdf:RDF',
  20                           array('xmlns' => "http://purl.org/rss/1.0/",
  21                                 'xmlns:rdf' => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'));
  22
  23         $this->_modules = array(
  24             //Standards
  25             'content'   => "http://purl.org/rss/1.0/modules/content/",
  26             'dc'        => "http://purl.org/dc/elements/1.1/",
  27             'sy'        => "http://purl.org/rss/1.0/modules/syndication/",
  28             //Proposed
  29             'wiki'      => "http://purl.org/rss/1.0/modules/wiki/",
  30             'ag'        => "http://purl.org/rss/1.0/modules/aggregation/",
  31             'annotate'  => "http://purl.org/rss/1.0/modules/annotate/",
  32             'audio'     => "http://media.tangent.org/rss/1.0/",
  33             'cp'        => "http://my.theinfo.org/changed/1.0/rss/",
  34             'rss091'    => "http://purl.org/rss/1.0/modules/rss091/",
  35             'slash'     => "http://purl.org/rss/1.0/modules/slash/",
  36             'taxo'      => "http://purl.org/rss/1.0/modules/taxonomy/",
  37             'thr'       => "http://purl.org/rss/1.0/modules/threading/"
  38             );
  39
  40         $this->_uris_seen = array();
  41         $this->_items = array();
  42     }
  43
  44     function registerModule($alias, $uri) {
  45         assert(!isset($this->_modules[$alias]));
  46         $this->_modules[$alias] = $uri;
  47     }
  48
  49     // Args should include:
  50     //  'title', 'link', 'description'
  51     // and can include:
  52     //  'URI'
  53     function channel($properties, $uri = false) {
  54         $this->_channel = $this->__node('channel', $properties, $uri);
  55     }
  56
  57     // Args should include:
  58     //  'title', 'link'
  59     // and can include:
  60     //  'description', 'URI'
  61     function addItem($properties, $uri = false) {
  62         $this->_items[] = $this->__node('item', $properties, $uri);
  63     }
  64
  65     // Args should include:
  66     //  'url', 'title', 'link'
  67     // and can include:
  68     //  'URI'
  69     function image($properties, $uri = false) {
  70         $this->_image = $this->__node('image', $properties, $uri);
  71     }
  72
  73     // Args should include:
  74     //  'title', 'description', 'name', and 'link'
  75     // and can include:
  76     //  'URI'
  77     function textinput($properties, $uri = false) {
  78         $this->_textinput = $this->__node('textinput', $properties, $uri);
  79     }
  80
  81     /**
  82      * Finish construction of RSS.
  83      */
  84     function finish() {
  85         if (isset($this->_finished))
  86             return;
  87
  88         $channel = &$this->_channel;
  89         $items = &$this->_items;
  90
  91         $seq = new XmlElement('rdf:Seq');
  92         if ($items) {
  93             foreach ($items as $item)
  94                 $seq->pushContent($this->__ref('rdf:li', $item));
  95         }
  96         $channel->pushContent(new XmlElement('items', false, $seq));
  97
  98         if (isset($this->_image)) {
  99             $channel->pushContent($this->__ref('image', $this->_image));
 100             $items[] = $this->_image;
 101         }
 102         if (isset($this->_textinput)) {
 103             $channel->pushContent($this->__ref('textinput', $this->_textinput));
 104             $items[] = $this->_textinput;
 105         }
 106
 107         $this->pushContent($channel);
 108         if ($items)
 109             $this->pushContent($items);
 110
 111         $this->__spew();
 112         $this->_finished = true;
 113     }
 114
 115
 116     /**
 117      * Write output to HTTP client.
 118      */
 119     function __spew() {
 120         header("Content-Type: application/xml; charset=" . RSS_ENCODING);
 121         printf("<?xml version=\"1.0\" encoding=\"%s\"?>\n", RSS_ENCODING);
 122         printf("<!-- generator=\"PhpWiki-%s\" -->\n", PHPWIKI_VERSION);
 123         $this->printXML();
 124     }
 125
 126
 127     /**
 128      * Create a new RDF <em>typedNode</em>.
 129      */
 130     function __node($type, $properties, $uri = false) {
 131         if (! $uri)
 132             $uri = $properties['link'];
 133         $attr['rdf:about'] = $this->__uniquify_uri($uri);
 134         return new XmlElement($type, $attr,
 135                               $this->__elementize($properties));
 136     }
 137
 138     /**
 139      * Check object URI for uniqueness, create a unique URI if needed.
 140      */
 141     function __uniquify_uri ($uri) {
 142         if (!$uri || isset($this->_uris_seen[$uri])) {
 143             $n = count($this->_uris_seen);
 144             $uri = $this->_channel->getAttr('rdf:about') . "#uri$n";
 145             assert(!isset($this->_uris_seen[$uri]));
 146         }
 147         $this->_uris_seen[$uri] = true;
 148         return $uri;
 149     }
 150
 151     /**
 152      * Convert hash of RDF properties to <em>propertyElt</em>s.
 153      */
 154     function __elementize ($elements) {
 155         $out = array();
 156         foreach ($elements as $prop => $val) {
 157             $this->__check_predicate($prop);
 158             $out[] = new XmlElement($prop, false, $val);
 159         }
 160         return $out;
 161     }
 162
 163     /**
 164      * Check property predicates for XMLNS sanity.
 165      */
 166     function __check_predicate ($name) {
 167         if (preg_match('/^([^:]+):[^:]/', $name, $m)) {
 168             $ns = $m[1];
 169             if (! $this->getAttr("xmlns:$ns")) {
 170                 if (!isset($this->_modules[$ns]))
 171                     die("$name: unknown namespace ($ns)");
 172                 $this->setAttr("xmlns:$ns", $this->_modules[$ns]);
 173             }
 174         }
 175     }
 176
 177     /**
 178      * Create a <em>propertyElt</em> which references another node in the RSS.
 179      */
 180     function __ref($predicate, $reference) {
 181         $attr['rdf:resource'] = $reference->getAttr('rdf:about');
 182         return new XmlElement($predicate, $attr);
 183     }
 184 };
 185
 186
 187 // (c-file-style: "gnu")
 188 // Local Variables:
 189 // mode: php
 190 // tab-width: 8
 191 // c-basic-offset: 4
 192 // c-hanging-comment-ender-p: nil
 193 // indent-tabs-mode: nil
 194 // End:
 195 ?>