419 lines
12 KiB
PHP
419 lines
12 KiB
PHP
<?php
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/**
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* This file is part of RSS-Bridge, a PHP project capable of generating RSS and
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* Atom feeds for websites that don't have one.
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*
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* For the full license information, please view the UNLICENSE file distributed
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* with this source code.
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*
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* @package Core
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* @license http://unlicense.org/ UNLICENSE
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* @link https://github.com/rss-bridge/rss-bridge
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*/
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/**
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* An abstract class for bridges that need to transform existing RSS or Atom
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* feeds.
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*
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* This class extends {@see BridgeAbstract} with functions to extract contents
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* from existing RSS or Atom feeds. Bridges that need to transform existing feeds
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* should inherit from this class instead of {@see BridgeAbstract}.
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*
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* Bridges that extend this class don't need to concern themselves with getting
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* contents from existing feeds, but can focus on adding additional contents
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* (i.e. by downloading additional data), filtering or just transforming a feed
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* into another format.
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*
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* @link http://www.rssboard.org/rss-0-9-1 RSS 0.91 Specification
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* @link http://web.resource.org/rss/1.0/spec RDF Site Summary (RSS) 1.0
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* @link http://www.rssboard.org/rss-specification RSS 2.0 Specification
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* @link https://tools.ietf.org/html/rfc4287 The Atom Syndication Format
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*
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* @todo The parsing functions should all be private. This class is complicated
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* enough without having to consider children overriding functions.
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*/
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abstract class FeedExpander extends BridgeAbstract {
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/** Indicates an RSS 1.0 feed */
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const FEED_TYPE_RSS_1_0 = 'RSS_1_0';
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/** Indicates an RSS 2.0 feed */
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const FEED_TYPE_RSS_2_0 = 'RSS_2_0';
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/** Indicates an Atom 1.0 feed */
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const FEED_TYPE_ATOM_1_0 = 'ATOM_1_0';
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/**
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* Holds the title of the current feed
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*
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* @var string
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*/
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private $title;
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/**
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* Holds the URI of the feed
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*
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* @var string
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*/
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private $uri;
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/**
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* Holds the feed type during internal operations.
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*
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* @var string
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*/
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private $feedType;
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/**
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* Collects data from an existing feed.
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*
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* Children should call this function in {@see BridgeInterface::collectData()}
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* to extract a feed.
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*
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* @param string $url URL to the feed.
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* @param int $maxItems Maximum number of items to collect from the feed
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* (`-1`: no limit).
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* @return self
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*/
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public function collectExpandableDatas($url, $maxItems = -1){
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if(empty($url)) {
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returnServerError('There is no $url for this RSS expander');
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}
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Debug::log('Loading from ' . $url);
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/* Notice we do not use cache here on purpose:
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* we want a fresh view of the RSS stream each time
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*/
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$content = getContents($url)
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or returnServerError('Could not request ' . $url);
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$rssContent = simplexml_load_string(trim($content));
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Debug::log('Detecting feed format/version');
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switch(true) {
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case isset($rssContent->item[0]):
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Debug::log('Detected RSS 1.0 format');
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$this->feedType = self::FEED_TYPE_RSS_1_0;
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break;
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case isset($rssContent->channel[0]):
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Debug::log('Detected RSS 0.9x or 2.0 format');
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$this->feedType = self::FEED_TYPE_RSS_2_0;
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break;
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case isset($rssContent->entry[0]):
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Debug::log('Detected ATOM format');
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$this->feedType = self::FEED_TYPE_ATOM_1_0;
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break;
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default:
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Debug::log('Unknown feed format/version');
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returnServerError('The feed format is unknown!');
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break;
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}
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Debug::log('Calling function "collect_' . $this->feedType . '_data"');
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$this->{'collect_' . $this->feedType . '_data'}($rssContent, $maxItems);
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return $this;
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}
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/**
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* Collect data from a RSS 1.0 compatible feed
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*
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* @link http://web.resource.org/rss/1.0/spec RDF Site Summary (RSS) 1.0
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*
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* @param string $rssContent The RSS content
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* @param int $maxItems Maximum number of items to collect from the feed
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* (`-1`: no limit).
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* @return void
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*
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* @todo Instead of passing $maxItems to all functions, just add all items
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* and remove excessive items later.
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*/
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protected function collect_RSS_1_0_data($rssContent, $maxItems){
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$this->load_RSS_2_0_feed_data($rssContent->channel[0]);
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foreach($rssContent->item as $item) {
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Debug::log('parsing item ' . var_export($item, true));
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$tmp_item = $this->parseItem($item);
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if (!empty($tmp_item)) {
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$this->items[] = $tmp_item;
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}
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if($maxItems !== -1 && count($this->items) >= $maxItems) break;
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}
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}
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/**
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* Collect data from a RSS 2.0 compatible feed
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*
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* @link http://www.rssboard.org/rss-specification RSS 2.0 Specification
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*
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* @param object $rssContent The RSS content
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* @param int $maxItems Maximum number of items to collect from the feed
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* (`-1`: no limit).
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* @return void
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*
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* @todo Instead of passing $maxItems to all functions, just add all items
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* and remove excessive items later.
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*/
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protected function collect_RSS_2_0_data($rssContent, $maxItems){
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$rssContent = $rssContent->channel[0];
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Debug::log('RSS content is ===========\n'
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. var_export($rssContent, true)
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. '===========');
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$this->load_RSS_2_0_feed_data($rssContent);
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foreach($rssContent->item as $item) {
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Debug::log('parsing item ' . var_export($item, true));
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$tmp_item = $this->parseItem($item);
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if (!empty($tmp_item)) {
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$this->items[] = $tmp_item;
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}
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if($maxItems !== -1 && count($this->items) >= $maxItems) break;
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}
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}
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/**
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* Collect data from a Atom 1.0 compatible feed
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*
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* @link https://tools.ietf.org/html/rfc4287 The Atom Syndication Format
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*
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* @param object $content The Atom content
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* @param int $maxItems Maximum number of items to collect from the feed
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* (`-1`: no limit).
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* @return void
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*
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* @todo Instead of passing $maxItems to all functions, just add all items
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* and remove excessive items later.
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*/
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protected function collect_ATOM_1_0_data($content, $maxItems){
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$this->load_ATOM_feed_data($content);
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foreach($content->entry as $item) {
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Debug::log('parsing item ' . var_export($item, true));
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$tmp_item = $this->parseItem($item);
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if (!empty($tmp_item)) {
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$this->items[] = $tmp_item;
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}
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if($maxItems !== -1 && count($this->items) >= $maxItems) break;
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}
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}
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/**
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* Convert RSS 2.0 time to timestamp
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*
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* @param object $item A feed item
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* @return int The timestamp
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*/
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protected function RSS_2_0_time_to_timestamp($item){
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return DateTime::createFromFormat('D, d M Y H:i:s e', $item->pubDate)->getTimestamp();
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}
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/**
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* Load RSS 2.0 feed data into RSS-Bridge
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*
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* @param object $rssContent The RSS content
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* @return void
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*
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* @todo set title, link, description, language, and so on
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*/
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protected function load_RSS_2_0_feed_data($rssContent){
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$this->title = trim((string)$rssContent->title);
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$this->uri = trim((string)$rssContent->link);
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}
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/**
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* Load Atom feed data into RSS-Bridge
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*
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* @param object $content The Atom content
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* @return void
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*/
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protected function load_ATOM_feed_data($content){
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$this->title = (string)$content->title;
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// Find best link (only one, or first of 'alternate')
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if(!isset($content->link)) {
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$this->uri = '';
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} elseif (count($content->link) === 1) {
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$this->uri = (string)$content->link[0]['href'];
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} else {
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$this->uri = '';
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foreach($content->link as $link) {
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if(strtolower($link['rel']) === 'alternate') {
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$this->uri = (string)$link['href'];
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break;
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}
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}
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}
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}
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/**
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* Parse the contents of a single Atom feed item into a RSS-Bridge item for
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* further transformation.
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*
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* @param object $feedItem A single feed item
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* @return object The RSS-Bridge item
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*
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* @todo To reduce confusion, the RSS-Bridge item should maybe have a class
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* of its own?
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*/
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protected function parseATOMItem($feedItem){
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// Some ATOM entries also contain RSS 2.0 fields
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$item = $this->parseRSS_2_0_Item($feedItem);
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if(isset($feedItem->id)) $item['uri'] = (string)$feedItem->id;
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if(isset($feedItem->title)) $item['title'] = (string)$feedItem->title;
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if(isset($feedItem->updated)) $item['timestamp'] = strtotime((string)$feedItem->updated);
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if(isset($feedItem->author)) $item['author'] = (string)$feedItem->author->name;
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if(isset($feedItem->content)) $item['content'] = (string)$feedItem->content;
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//When "link" field is present, URL is more reliable than "id" field
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if (count($feedItem->link) === 1) {
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$item['uri'] = (string)$feedItem->link[0]['href'];
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} else {
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foreach($feedItem->link as $link) {
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if(strtolower($link['rel']) === 'alternate') {
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$item['uri'] = (string)$link['href'];
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break;
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}
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}
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}
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return $item;
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}
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/**
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* Parse the contents of a single RSS 0.91 feed item into a RSS-Bridge item
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* for further transformation.
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*
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* @param object $feedItem A single feed item
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* @return object The RSS-Bridge item
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*
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* @todo To reduce confusion, the RSS-Bridge item should maybe have a class
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* of its own?
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*/
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protected function parseRSS_0_9_1_Item($feedItem){
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$item = array();
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if(isset($feedItem->link)) $item['uri'] = (string)$feedItem->link;
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if(isset($feedItem->title)) $item['title'] = (string)$feedItem->title;
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// rss 0.91 doesn't support timestamps
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// rss 0.91 doesn't support authors
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// rss 0.91 doesn't support enclosures
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if(isset($feedItem->description)) $item['content'] = (string)$feedItem->description;
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return $item;
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}
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/**
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* Parse the contents of a single RSS 1.0 feed item into a RSS-Bridge item
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* for further transformation.
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*
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* @param object $feedItem A single feed item
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* @return object The RSS-Bridge item
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*
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* @todo To reduce confusion, the RSS-Bridge item should maybe have a class
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* of its own?
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*/
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protected function parseRSS_1_0_Item($feedItem){
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// 1.0 adds optional elements around the 0.91 standard
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$item = $this->parseRSS_0_9_1_Item($feedItem);
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$namespaces = $feedItem->getNamespaces(true);
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if(isset($namespaces['dc'])) {
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$dc = $feedItem->children($namespaces['dc']);
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if(isset($dc->date)) $item['timestamp'] = strtotime((string)$dc->date);
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if(isset($dc->creator)) $item['author'] = (string)$dc->creator;
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}
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return $item;
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}
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/**
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* Parse the contents of a single RSS 2.0 feed item into a RSS-Bridge item
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* for further transformation.
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*
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* @param object $feedItem A single feed item
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* @return object The RSS-Bridge item
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*
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* @todo To reduce confusion, the RSS-Bridge item should maybe have a class
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* of its own?
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*/
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protected function parseRSS_2_0_Item($feedItem){
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// Primary data is compatible to 0.91 with some additional data
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$item = $this->parseRSS_0_9_1_Item($feedItem);
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$namespaces = $feedItem->getNamespaces(true);
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if(isset($namespaces['dc'])) $dc = $feedItem->children($namespaces['dc']);
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if(isset($namespaces['media'])) $media = $feedItem->children($namespaces['media']);
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if(isset($feedItem->guid)) {
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foreach($feedItem->guid->attributes() as $attribute => $value) {
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if($attribute === 'isPermaLink'
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&& ($value === 'true' || (
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filter_var($feedItem->guid, FILTER_VALIDATE_URL)
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&& (empty($item['uri']) || !filter_var($item['uri'], FILTER_VALIDATE_URL))
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)
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)
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) {
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$item['uri'] = (string)$feedItem->guid;
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break;
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}
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}
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}
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if(isset($feedItem->pubDate)) {
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$item['timestamp'] = strtotime((string)$feedItem->pubDate);
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} elseif(isset($dc->date)) {
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$item['timestamp'] = strtotime((string)$dc->date);
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}
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if(isset($feedItem->author)) {
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$item['author'] = (string)$feedItem->author;
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} elseif (isset($feedItem->creator)) {
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$item['author'] = (string)$feedItem->creator;
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} elseif(isset($dc->creator)) {
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$item['author'] = (string)$dc->creator;
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} elseif(isset($media->credit)) {
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$item['author'] = (string)$media->credit;
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}
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if(isset($feedItem->enclosure) && !empty($feedItem->enclosure['url'])) {
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$item['enclosures'] = array((string)$feedItem->enclosure['url']);
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}
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return $item;
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}
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/**
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* Parse the contents of a single feed item, depending on the current feed
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* type, into a RSS-Bridge item.
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*
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* @param object $item The current feed item
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* @return object A RSS-Bridge item, with (hopefully) the whole content
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*/
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protected function parseItem($item){
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switch($this->feedType) {
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case self::FEED_TYPE_RSS_1_0:
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return $this->parseRSS_1_0_Item($item);
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break;
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case self::FEED_TYPE_RSS_2_0:
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return $this->parseRSS_2_0_Item($item);
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break;
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case self::FEED_TYPE_ATOM_1_0:
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return $this->parseATOMItem($item);
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break;
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default: returnClientError('Unknown version ' . $this->getInput('version') . '!');
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}
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}
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/** {@inheritdoc} */
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public function getURI(){
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return !empty($this->uri) ? $this->uri : parent::getURI();
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}
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/** {@inheritdoc} */
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public function getName(){
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return !empty($this->title) ? $this->title : parent::getName();
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}
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/** {@inheritdoc} */
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public function getIcon(){
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return !empty($this->icon) ? $this->icon : parent::getIcon();
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}
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}
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