<?php
/**
* SeekQuarry/Yioop --
* Open Source Pure PHP Search Engine, Crawler, and Indexer
*
* Copyright (C) 2009 - 2018 Chris Pollett chris@pollett.org
*
* LICENSE:
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
* END LICENSE
*
* @author Chris Pollett chris@pollett.org
* @license https://www.gnu.org/licenses/ GPL3
* @link https://www.seekquarry.com/
* @copyright 2009 - 2018
* @filesource
*/
namespace seekquarry\yioop\library\processors;
use seekquarry\yioop\configs as C;
use seekquarry\yioop\library\UrlParser;
/**
* Used to create crawl summary information
* for RSS or Atom files
*
* @author Chris Pollett
*/
class RssProcessor extends TextProcessor
{
/**
* Set-ups the any indexing plugins associated with this page
* processor
*
* @param array $plugins an array of indexing plugins which might
* do further processing on the data handles by this page
* processor
* @param int $max_description_len maximal length of a page summary
* @param string $summarizer_option CRAWL_CONSTANT specifying what kind
* of summarizer to use self::BASIC_SUMMARIZER,
* self::GRAPH_BASED_SUMMARIZER and self::CENTROID_SUMMARIZER
* self::CENTROID_SUMMARIZER
*/
public function __construct($plugins = [], $max_description_len = null,
$summarizer_option = self::BASIC_SUMMARIZER)
{
parent::__construct($plugins, $max_description_len, $summarizer_option);
/** Register File Types We Handle*/
self::$indexed_file_types[] = "rss";
self::$mime_processor["application/rss+xml"] = "RssProcessor";
self::$mime_processor["application/atom+xml"] = "RssProcessor";
}
/**
* Used to extract the title, description and links from
* a string consisting of rss or atom news feed data.
*
* @param string $page web-page contents
* @param string $url the url where the page contents came from,
* used to canonicalize relative links
*
* @return array a summary of the contents of the page
*
*/
public function process($page, $url)
{
$summary = null;
if (is_string($page)) {
$dom = self::dom($page);
$atom = false;
$feed_nodes = $dom->getElementsByTagName('feed');
if ($feed_nodes->length > 0) {
$atom = true;
}
if ($dom !==false) {
$summary[self::TITLE] = self::title($dom, $atom);
$summary[self::DESCRIPTION] = self::description($dom, $atom);
$summary[self::LANG] = self::lang($dom,
$summary[self::DESCRIPTION]);
$summary[self::LINKS] = self::links($dom, $url, $atom);
if (strlen($summary[self::DESCRIPTION] . $summary[self::TITLE])
== 0 && count($summary[self::LINKS]) == 0) {
//maybe not rss or atom? treat as text still try to get urls
$summary = parent::process($page, $url);
}
}
}
return $summary;
}
/**
* Determines the language of the rss document by looking at the channel
* language tag
*
* @param object $dom - a document object to check the language of
* @param string $sample_text sample text to try guess the language from
* @param string $url guess lang from url as fallback
*
* @return string language tag for guessed language
*/
public static function lang($dom, $sample_text = null, $url = null)
{
$xpath = new \DOMXPath($dom);
$languages = $xpath->evaluate("/rss/channel/language");
if ($languages && is_object($languages) &&
is_object($languages->item(0))) {
return $languages->item(0)->textContent;
} else {
$lang = self::calculateLang($sample_text, $url);
}
return $lang;
}
/**
* Return a document object based on a string containing the contents of
* an RSS page
*
* @param string $page a web page
*
* @return object document object
*/
public static function dom($page)
{
$dom = new \DOMDocument();
@$dom->loadXML($page);
return $dom;
}
/**
* Returns html head title of a webpage based on its document object
*
* @param object $dom a document object to extract a title from.
* @param bool $atom if the feed is atom or rss
* @return string a title of the page
*
*/
public static function title($dom, $atom = false)
{
$sites = [];
$xpath = new \DOMXPath($dom);
if ($atom){
$xpath->registerNamespace('atom', "http://www.w3.org/2005/Atom");
}
$title_query = ($atom) ? "/feed/title|/atom:feed/atom:title" :
"/rss/channel/title";
$titles = $xpath->evaluate($title_query);
$title = "";
foreach ($titles as $pre_title) {
$title .= $pre_title->textContent;
}
return $title;
}
/**
* Returns descriptive text concerning a webpage based on its document
* object
*
* @param object $dom a document object to extract a description from.
* @param bool $atom if the feed is atom or rss
* @return string a description of the page
*/
public static function description($dom, $atom = false) {
$sites = [];
$xpath = new \DOMXPath($dom);
$description = "";
/*
concatenate the contents of these dom elements up to
the limit of description length
*/
$page_parts = ["/rss/channel/description",
"/rss/channel/category", "/rss/channel/lastBuildDate",
"/rss/channel/copyright"];
if ($atom) {
$xpath->registerNamespace('atom', "http://www.w3.org/2005/Atom");
$page_parts = ["/feed/subtitle", "/feed/author",
"/feed/updated", "/feed/rights", "/feed/generator",
"/atom:feed/atom:subtitle", "/atom:feed/atom:author",
"/atom:feed/atom:updated", "/atom:feed/atom:rights",
"/atom:feed/atom:generator"];
}
foreach ($page_parts as $part) {
$doc_nodes = $xpath->evaluate($part);
foreach ($doc_nodes as $node) {
$description .= " ".$node->textContent;
if (strlen($description) > self::$max_description_len) {
break 2;
}
}
}
$description = mb_ereg_replace("(\s)+", " ", $description);
return $description;
}
/**
* Returns up to MAX_LINK_PER_PAGE many links from the supplied
* dom object where links have been canonicalized according to
* the supplied $site information.
*
* @param object $dom a document object with links on it
* @param string $site a string containing a url
* @param bool $atom if the feed is atom or rss
*
* @return array links from the $dom object
*/
public static function links($dom, $site, $atom = false)
{
$sites = [];
$xpath = new \DOMXPath($dom);
$link_nodes = [
"/rss/channel" => [ "url" =>"link", "text" => "title"],
"/rss/channel/image" => [ "url" =>"url", "text" => "title"],
"/rss/channel/item" => [ "url" =>"link", "text" => "title"],
];
if ($atom) {
$xpath->registerNamespace('atom', "http://www.w3.org/2005/Atom");
$link_nodes = [
"/feed/entry" => [ "url" =>"link", "text" => "title"],
"/atom:feed/atom:entry"
=> [ "url" =>"link", "text" => "title"],
];
}
$i = 0;
foreach ($link_nodes as $path => $url_text_pair) {
$nodes = $xpath->evaluate($path);
foreach ($nodes as $node) {
$result = self::linkAndTexts($node,
$url_text_pair['url'], $url_text_pair['text'], $site,
$atom);
if ($result != false) {
list($url, $text) = $result;
$sites[$url] = $text;
$i++;
}
if ($i >= C\MAX_LINKS_TO_EXTRACT) {
break 2;
}
}
}
return $sites;
}
/**
* Returns a url text pair where the url comes from the link of
* the given item node and the text comes from the text data for that node.
* urls are canonicalized according to site.
*
* @param object $item_node the DOMNode to get a link and text from
* @param string $link_name name of link tag
* @param string $text_name name of text tag to associate with link
* @param string $site a string containing a url
* @param bool $atom if the feed is atom or rss
*
* @return array a url,text pair
*/
public static function linkAndTexts($item_node, $link_name, $text_name,
$site, $atom = false)
{
$text = "";
foreach ($item_node->childNodes as $node) {
if ($node->nodeName == $link_name) {
if (!$atom) {
$url = UrlParser::canonicalLink(
$node->textContent, $site);
} else {
$url = UrlParser::canonicalLink(
$node->getAttribute("href"), $site);
}
if ($url === null || $url === "" ||
UrlParser::checkRecursiveUrl($url) ||
strlen($url) >= C\MAX_URL_LEN) {
return false;
}
}
if ($node->nodeName == $text_name) {
$text = $node->textContent;
if ($text == "") {
$text = "RSS Feed";
if ($atom) {
$text = "Atom Feed";
}
}
}
}
if (!isset($url) || $url == "") return false;
$text = mb_ereg_replace("(\s)+", " ", $text);
return [$url, $text];
}
}