lib/RssWriter.php

   1 <?php rcs_id('$Id: RssWriter.php,v 1.10 2004-11-21 11:59:16 rurban Exp $');
   2 /*
   3  * Code for creating RSS 1.0.
   4  */
   5
   6 // Encoding for RSS output.
   7 define('RSS_ENCODING', $GLOBALS['charset']);
   8
   9 /**
  10  * A class for writing RSS 1.0.
  11  *
  12  * @see http://purl.org/rss/1.0/spec,
  13  *      http://www.usemod.com/cgi-bin/mb.pl?ModWiki
  14  */
  15 class RssWriter extends XmlElement
  16 {
  17     function RssWriter () {
  18         $this->XmlElement('rdf:RDF',
  19                           array('xmlns' => "http://purl.org/rss/1.0/",
  20                                 'xmlns:rdf' => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'));
  21
  22         $this->_modules = array(
  23             //Standards
  24             'content'   => "http://purl.org/rss/1.0/modules/content/",
  25             'dc'        => "http://purl.org/dc/elements/1.1/",
  26             'sy'        => "http://purl.org/rss/1.0/modules/syndication/",
  27             //Proposed
  28             'wiki'      => "http://purl.org/rss/1.0/modules/wiki/",
  29             'ag'        => "http://purl.org/rss/1.0/modules/aggregation/",
  30             'annotate'  => "http://purl.org/rss/1.0/modules/annotate/",
  31             'audio'     => "http://media.tangent.org/rss/1.0/",
  32             'cp'        => "http://my.theinfo.org/changed/1.0/rss/",
  33             'rss091'    => "http://purl.org/rss/1.0/modules/rss091/",
  34             'slash'     => "http://purl.org/rss/1.0/modules/slash/",
  35             'taxo'      => "http://purl.org/rss/1.0/modules/taxonomy/",
  36             'thr'       => "http://purl.org/rss/1.0/modules/threading/"
  37             );
  38
  39         $this->_uris_seen = array();
  40         $this->_items = array();
  41     }
  42
  43     function registerModule($alias, $uri) {
  44         assert(!isset($this->_modules[$alias]));
  45         $this->_modules[$alias] = $uri;
  46     }
  47
  48     // Args should include:
  49     //  'title', 'link', 'description'
  50     // and can include:
  51     //  'URI'
  52     function channel($properties, $uri = false) {
  53         $this->_channel = $this->__node('channel', $properties, $uri);
  54     }
  55
  56     // Args should include:
  57     //  'title', 'link'
  58     // and can include:
  59     //  'description', 'URI'
  60     function addItem($properties, $uri = false) {
  61         $this->_items[] = $this->__node('item', $properties, $uri);
  62     }
  63
  64     // Args should include:
  65     //  'url', 'title', 'link'
  66     // and can include:
  67     //  'URI'
  68     function image($properties, $uri = false) {
  69         $this->_image = $this->__node('image', $properties, $uri);
  70     }
  71
  72     // Args should include:
  73     //  'title', 'description', 'name', and 'link'
  74     // and can include:
  75     //  'URI'
  76     function textinput($properties, $uri = false) {
  77         $this->_textinput = $this->__node('textinput', $properties, $uri);
  78     }
  79
  80     /**
  81      * Finish construction of RSS.
  82      */
  83     function finish() {
  84         if (isset($this->_finished))
  85             return;
  86
  87         $channel = &$this->_channel;
  88         $items = &$this->_items;
  89
  90         $seq = new XmlElement('rdf:Seq');
  91         if ($items) {
  92             foreach ($items as $item)
  93                 $seq->pushContent($this->__ref('rdf:li', $item));
  94         }
  95         $channel->pushContent(new XmlElement('items', false, $seq));
  96
  97         if (isset($this->_image)) {
  98             $channel->pushContent($this->__ref('image', $this->_image));
  99             $items[] = $this->_image;
 100         }
 101         if (isset($this->_textinput)) {
 102             $channel->pushContent($this->__ref('textinput', $this->_textinput));
 103             $items[] = $this->_textinput;
 104         }
 105
 106         $this->pushContent($channel);
 107         if ($items)
 108             $this->pushContent($items);
 109
 110         $this->__spew();
 111         $this->_finished = true;
 112     }
 113
 114
 115     /**
 116      * Write output to HTTP client.
 117      */
 118     function __spew() {
 119         header("Content-Type: application/xml; charset=" . RSS_ENCODING);
 120         printf("<?xml version=\"1.0\" encoding=\"%s\"?>\n", RSS_ENCODING);
 121         $this->printXML();
 122     }
 123
 124
 125     /**
 126      * Create a new RDF <em>typedNode</em>.
 127      */
 128     function __node($type, $properties, $uri = false) {
 129         if (! $uri)
 130             $uri = $properties['link'];
 131         $attr['rdf:about'] = $this->__uniquify_uri($uri);
 132         return new XmlElement($type, $attr,
 133                               $this->__elementize($properties));
 134     }
 135
 136     /**
 137      * Check object URI for uniqueness, create a unique URI if needed.
 138      */
 139     function __uniquify_uri ($uri) {
 140         if (!$uri || isset($this->_uris_seen[$uri])) {
 141             $n = count($this->_uris_seen);
 142             $uri = $this->_channel->getAttr('rdf:about') . "#uri$n";
 143             assert(!isset($this->_uris_seen[$uri]));
 144         }
 145         $this->_uris_seen[$uri] = true;
 146         return $uri;
 147     }
 148
 149     /**
 150      * Convert hash of RDF properties to <em>propertyElt</em>s.
 151      */
 152     function __elementize ($elements) {
 153         $out = array();
 154         foreach ($elements as $prop => $val) {
 155             $this->__check_predicate($prop);
 156             $out[] = new XmlElement($prop, false, $val);
 157         }
 158         return $out;
 159     }
 160
 161     /**
 162      * Check property predicates for XMLNS sanity.
 163      */
 164     function __check_predicate ($name) {
 165         if (preg_match('/^([^:]+):[^:]/', $name, $m)) {
 166             $ns = $m[1];
 167             if (! $this->getAttr("xmlns:$ns")) {
 168                 if (!isset($this->_modules[$ns]))
 169                     die("$name: unknown namespace ($ns)");
 170                 $this->setAttr("xmlns:$ns", $this->_modules[$ns]);
 171             }
 172         }
 173     }
 174
 175     /**
 176      * Create a <em>propertyElt</em> which references another node in the RSS.
 177      */
 178     function __ref($predicate, $reference) {
 179         $attr['rdf:resource'] = $reference->getAttr('rdf:about');
 180         return new XmlElement($predicate, $attr);
 181     }
 182 };
 183
 184
 185 // (c-file-style: "gnu")
 186 // Local Variables:
 187 // mode: php
 188 // tab-width: 8
 189 // c-basic-offset: 4
 190 // c-hanging-comment-ender-p: nil
 191 // indent-tabs-mode: nil
 192 // End:
 193 ?>