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<?php
/**
* Arc90's Readability ported to PHP for FiveFilters.org
* Based on readability.js version 1.7.1 (without multi-page support)
* ------------------------------------------------------
* Original URL: http://lab.arc90.com/experiments/readability/js/readability.js
* Arc90's project URL: http://lab.arc90.com/experiments/readability/
* JS Source: http://code.google.com/p/arc90labs-readability
* Ported by: Keyvan Minoukadeh, http://www.keyvan.net
* More information: http://fivefilters.org/content-only/
* License: Apache License, Version 2.0
* Requires: PHP5
* Date: 2011-07-22
*
* Differences between the PHP port and the original
* ------------------------------------------------------
* Arc90's Readability is designed to run in the browser. It works on the DOM
* tree (the parsed HTML) after the page's CSS styles have been applied and
* Javascript code executed. This PHP port does not run inside a browser.
* We use PHP's ability to parse HTML to build our DOM tree, but we cannot
* rely on CSS or Javascript support. As such, the results will not always
* match Arc90's Readability. (For example, if a web page contains CSS style
* rules or Javascript code which hide certain HTML elements from display,
* Arc90's Readability will dismiss those from consideration but our PHP port,
* unable to understand CSS or Javascript, will not know any better.)
*
* Another significant difference is that the aim of Arc90's Readability is
* to re-present the main content block of a given web page so users can
* read it more easily in their browsers. Correct identification, clean up,
* and separation of the content block is only a part of this process.
* This PHP port is only concerned with this part, it does not include code
* that relates to presentation in the browser - Arc90 already do
* that extremely well, and for PDF output there's FiveFilters.org's
* PDF Newspaper: http://fivefilters.org/pdf-newspaper/.
*
* Finally, this class contains methods that might be useful for developers
* working on HTML document fragments. So without deviating too much from
* the original code (which I don't want to do because it makes debugging
* and updating more difficult), I've tried to make it a little more
* developer friendly. You should be able to use the methods here on
* existing DOMElement objects without passing an entire HTML document to
* be parsed.
*/
class Readability
{
public $version = '1.7.1-without-multi-page';
public $convertLinksToFootnotes = false;
public $revertForcedParagraphElements = true;
// public $articleTitle;
public $articleContent;
public $dom;
public $url = null; // optional - URL where HTML was retrieved
public $domain;
public $debug = false;
protected $body = null; //
protected $bodyCache = null; // Cache the body HTML in case we need to re-use it later
protected $flags = 7; // 1 | 2 | 4; // Start with all flags set.
protected $success = false; // indicates whether we were able to extract or not
/**
* All of the regular expressions in use within readability.
* Defined up here so we don't instantiate them repeatedly in loops.
**/
public $regexps = array(
'unlikelyCandidates' => '/combx|comment|community|disqus|extra|foot|header|menu|remark|rss|shoutbox|sidebar|sponsor|ad-break|agegate|pagination|pager|popup|tweet|twitter|like|share/i',
'okMaybeItsACandidate' => '/and|article|section|body|column|main|shadow/i',
'positive' => '/article|body|content|entry|hentry|main|page|pagination|post|text|blog|story|interactiveFreeFormMain|wikistyle|wp-post-image|featured|contentPane|cnnVPLeftCol/i',
'negative' => '/combx|comment|com-|contact|foot|footer|footnote|masthead|media|meta|navigation|outbrain|promo|related|scroll|share|shoutbox|sidebar|sponsor|shopping|tags|tool|widget|cnn_strylftcexpbx/i',
'divToPElements' => '/<(a|blockquote|dl|div|img|ol|p|pre|code|table|ul|iframe|object|embed)/i',
'replaceBrs' => '/(<br[^>]*>[ \n\r\t]*){2,}/i',
'replaceFonts' => '/<(\/?)font[^>]*>/i',
// 'trimRe' => '/^\s+|\s+$/g', // PHP has trim()
'normalize' => '/\s{2,}/',
'killBreaks' => '/(<br\s*\/?>(\s|&nbsp;?)*){1,}/',
'video' => '/http:\/\/(www\.)?(youtube|vimeo|kickstarter|youtube-nocookie|brightcove)\.com/i',
'skipFootnoteLink' => '/^\s*(\[?[a-z0-9]{1,2}\]?|^|edit|citation needed)\s*$/i'
);
/* constants */
const FLAG_STRIP_UNLIKELYS = 1;
const FLAG_WEIGHT_CLASSES = 2;
const FLAG_CLEAN_CONDITIONALLY = 4;
/**
* Create instance of Readability
* @param string UTF-8 encoded string
* @param string (optional) URL associated with HTML (used for footnotes)
*/
function __construct($html, $url=null, $domain)
{
/* Turn all double br's into p's */
$html = preg_replace($this->regexps['replaceBrs'], '</p><p>', $html);
$html = preg_replace($this->regexps['replaceFonts'], '<$1span>', $html);
$html = mb_convert_encoding($html, 'HTML-ENTITIES', "UTF-8");
$this->dom = new DOMDocument();
$this->dom->preserveWhiteSpace = false;
$this->dom->registerNodeClass('DOMElement', 'JSLikeHTMLElement');
if (trim($html) == '') $html = '<html></html>';
@$this->dom->loadHTML($html);
$this->url = $url;
$this->domain = $domain;
}
/**
* Get article title element
* @return DOMElement
*/
// public function getTitle() {
// return $this->articleTitle;
// }
/**
* Get article content element
* @return DOMElement
*/
public function getContent() {
return $this->articleContent;
}
/**
* Runs readability.
*
* Workflow:
* 1. Prep the document by removing script tags, css, etc.
* 2. Build readability's DOM tree.
* 3. Grab the article content from the current dom tree.
* 4. Replace the current DOM tree with the new one.
* 5. Read peacefully.
*
* @return boolean true if we found content, false otherwise
**/
public function init()
{
if (!isset($this->dom->documentElement)) return false;
$this->removeScripts($this->dom);
// Assume successful outcome
$this->success = true;
$bodyElems = $this->dom->getElementsByTagName('body');
if ($bodyElems->length > 0) {
if ($this->bodyCache == null) {
$this->bodyCache = $bodyElems->item(0)->innerHTML;
}
if ($this->body == null) {
$this->body = $bodyElems->item(0);
}
}
$this->prepDocument();
//die($this->dom->documentElement->parentNode->nodeType);
//$this->setInnerHTML($this->dom->documentElement, $this->getInnerHTML($this->dom->documentElement));
//die($this->getInnerHTML($this->dom->documentElement));
/* Build readability's DOM tree */
$overlay = $this->dom->createElement('div');
$innerDiv = $this->dom->createElement('div');
// $articleTitle = $this->getArticleTitle();
$articleContent = $this->grabArticle();
if (!$articleContent) {
$this->success = false;
$articleContent = $this->dom->createElement('div');
$articleContent->setAttribute('id', 'readability-content');
$articleContent->innerHTML = '<p>Sorry, Orange was unable to parse this page for content.</p>';
}
$overlay->setAttribute('id', 'readOverlay');
$innerDiv->setAttribute('id', 'readInner');
/* Glue the structure of our document together. */
// $innerDiv->appendChild($articleTitle);
$innerDiv->appendChild($articleContent);
$overlay->appendChild($innerDiv);
/* Clear the old HTML, insert the new content. */
$this->body->innerHTML = '';
$this->body->appendChild($overlay);
//document.body.insertBefore(overlay, document.body.firstChild);
$this->body->removeAttribute('style');
$this->parseImages($articleContent);
$this->convertSmartQuotes($articleContent);
// Set title and content instance variables
// $this->articleTitle = $articleTitle;
$this->articleContent = $articleContent;
return $this->success;
}
/**
* Debug
*/
protected function dbg($msg) {
if ($this->debug) echo '* ',$msg, '<br />', "\n";
}
/**
* Run any post-process modifications to article content as necessary.
*
* @param DOMElement
* @return void
*/
public function postProcessContent($articleContent) {
if ($this->convertLinksToFootnotes && !preg_match('/wikipedia\.org/', @$this->url)) {
$this->addFootnotes($articleContent);
}
}
/**
* Get the article title as an H1.
*
* @return DOMElement
*/
// protected function getArticleTitle() {
// $curTitle = '';
// $origTitle = '';
//
// try {
// $curTitle = $origTitle = $this->getInnerText($this->dom->getElementsByTagName('title')->item(0));
// } catch(Exception $e) {}
//
// if (preg_match('/ [\|\-] /', $curTitle))
// {
// $curTitle = preg_replace('/(.*)[\|\-] .*/i', '$1', $origTitle);
//
// if (count(explode(' ', $curTitle)) < 3) {
// $curTitle = preg_replace('/[^\|\-]*[\|\-](.*)/i', '$1', $origTitle);
// }
// }
// else if (strpos($curTitle, ': ') !== false)
// {
// $curTitle = preg_replace('/.*:(.*)/i', '$1', $origTitle);
//
// if (count(explode(' ', $curTitle)) < 3) {
// $curTitle = preg_replace('/[^:]*[:](.*)/i','$1', $origTitle);
// }
// }
// else if(strlen($curTitle) > 150 || strlen($curTitle) < 15)
// {
// $hOnes = $this->dom->getElementsByTagName('h1');
// if($hOnes->length == 1)
// {
// $curTitle = $this->getInnerText($hOnes->item(0));
// }
// }
//
// $curTitle = trim($curTitle);
//
// if (count(explode(' ', $curTitle)) <= 4) {
// $curTitle = $origTitle;
// }
//
// $articleTitle = $this->dom->createElement('h1');
// $articleTitle->innerHTML = $curTitle;
//
// return $articleTitle;
// }
/**
* Prepare the HTML document for readability to scrape it.
* This includes things like stripping javascript, CSS, and handling terrible markup.
*
* @return void
**/
protected function prepDocument() {
/**
* In some cases a body element can't be found (if the HTML is totally hosed for example)
* so we create a new body node and append it to the document.
*/
if ($this->body == null)
{
$this->body = $this->dom->createElement('body');
$this->dom->appendChild($this->body);
}
$this->body->setAttribute('id', 'readabilityBody');
/* Remove all style tags in head */
$styleTags = $this->dom->getElementsByTagName('style');
for ($i = $styleTags->length-1; $i >= 0; $i--)
{
$styleTags->item($i)->parentNode->removeChild($styleTags->item($i));
}
/* Turn all double br's into p's */
/* Note, this is pretty costly as far as processing goes. Maybe optimize later. */
//document.body.innerHTML = document.body.innerHTML.replace(readability.regexps.replaceBrs, '</p><p>').replace(readability.regexps.replaceFonts, '<$1span>');
// We do this in the constructor for PHP as that's when we have raw HTML - before parsing it into a DOM tree.
// Manipulating innerHTML as it's done in JS is not possible in PHP.
}
/**
* Replace smart quotes with apostrophes and quotes
* @return HTML String
*/
protected function convertSmartQuotes($string) {
$search = array(chr(145),
chr(146),
chr(147),
chr(148),
chr(151));
$replace = array("'",
"'",
'"',
'"',
'-');
return str_replace($search, $replace, $string);
}
/**
* Convert relative image path to absolute URL
* @return HTML String
*/
protected function rel2abs($rel, $base) {
/* queries and anchors */
if ($rel[0]=='#' || $rel[0]=='?') return $base.$rel;
/* parse base URL and convert to local variables:
$scheme, $host, $path */
extract(parse_url($base));
/* remove non-directory element from path */
$path = preg_replace('#/[^/]*$#', '', $path);
/* destroy path if relative url points to root */
if ($rel[0] == '/') $path = '';
/* dirty absolute URL */
$abs = "$host$path/$rel";
/* replace '//' or '/./' or '/foo/../' with '/' */
$re = array('#(/\.?/)#', '#/(?!\.\.)[^/]+/\.\./#');
for($n=1; $n>0; $abs=preg_replace($re, '/', $abs, -1, $n)) {}
/* absolute URL is ready! */
return $scheme.'://'.$abs;
}
/**
* Filter article content for valuable images
* @return HTML String
*/
protected function parseImages($articleContent) {
$articleImages = $articleContent->getElementsByTagName('img');
$imagesCount = $articleImages->length;
if ($imagesCount > 0) {
if ($imagesCount >= 30) {
for($i = $imagesCount-1; $i >= 0; $i--) {
$articleImages->item($i)->parentNode->removeChild($articleImages->item($i));
}
} else {
$bestImage = '';
$maxSize = -1;
for($i = $imagesCount-1; $i >= 0; $i--) {
$img = $articleImages->item($i);
$attrWidth = $img->getAttribute('width');
$attrHeight = $img->getAttribute('height');
if ($attrWidth && $attrWidth < 150 || $attrHeight && $attrHeight < 120) {
$img->parentNode->removeChild($img);
} else {
$src = $img->getAttribute('src');
if (substr($src, 0, 4) != 'http') {
$src = $this->rel2abs($src, $this->url);
}
list($width, $height) = getimagesize($src);
if ($width && $height) {
if ($width < 150 || $height && $height < 120) {
$img->parentNode->removeChild($img);
} else {
$img->setAttribute('src', $src);
if ($height && ($width + $height) > $maxSize) {
$maxSize = $width + $height;
$bestImage = $img;
}
}
}
}
}
if ($bestImage != '') {
$bestImage->setAttribute('class', 'orange-best-image');
}
}
}
}
/**
* For easier reading, convert this document to have footnotes at the bottom rather than inline links.
* @see http://www.roughtype.com/archives/2010/05/experiments_in.php
*
* @return void
**/
public function addFootnotes($articleContent) {
$footnotesWrapper = $this->dom->createElement('div');
$footnotesWrapper->setAttribute('id', 'readability-footnotes');
$footnotesWrapper->innerHTML = '<h3>References</h3>';
$articleFootnotes = $this->dom->createElement('ol');
$articleFootnotes->setAttribute('id', 'readability-footnotes-list');
$footnotesWrapper->appendChild($articleFootnotes);
$articleLinks = $articleContent->getElementsByTagName('a');
$linkCount = 0;
for ($i = 0; $i < $articleLinks->length; $i++)
{
$articleLink = $articleLinks->item($i);
$footnoteLink = $articleLink->cloneNode(true);
$refLink = $this->dom->createElement('a');
$footnote = $this->dom->createElement('li');
$linkDomain = @parse_url($footnoteLink->getAttribute('href'), PHP_URL_HOST);
if (!$linkDomain && isset($this->url)) $linkDomain = @parse_url($this->url, PHP_URL_HOST);
//linkDomain = footnoteLink.host ? footnoteLink.host : document.location.host,
$linkText = $this->getInnerText($articleLink);
if ((strpos($articleLink->getAttribute('class'), 'readability-DoNotFootnote') !== false) || preg_match($this->regexps['skipFootnoteLink'], $linkText)) {
continue;
}
$linkCount++;
/** Add a superscript reference after the article link */
$refLink->setAttribute('href', '#readabilityFootnoteLink-' . $linkCount);
$refLink->innerHTML = '<small><sup>[' . $linkCount . ']</sup></small>';
$refLink->setAttribute('class', 'readability-DoNotFootnote');
$refLink->setAttribute('style', 'color: inherit;');
//TODO: does this work or should we use DOMNode.isSameNode()?
if ($articleLink->parentNode->lastChild == $articleLink) {
$articleLink->parentNode->appendChild($refLink);
} else {
$articleLink->parentNode->insertBefore($refLink, $articleLink->nextSibling);
}
$articleLink->setAttribute('style', 'color: inherit; text-decoration: none;');
$articleLink->setAttribute('name', 'readabilityLink-' . $linkCount);
$footnote->innerHTML = '<small><sup><a href="#readabilityLink-' . $linkCount . '" title="Jump to Link in Article">^</a></sup></small> ';
$footnoteLink->innerHTML = ($footnoteLink->getAttribute('title') != '' ? $footnoteLink->getAttribute('title') : $linkText);
$footnoteLink->setAttribute('name', 'readabilityFootnoteLink-' . $linkCount);
$footnote->appendChild($footnoteLink);
if ($linkDomain) $footnote->innerHTML = $footnote->innerHTML . '<small> (' . $linkDomain . ')</small>';
$articleFootnotes->appendChild($footnote);
}
if ($linkCount > 0) {
$articleContent->appendChild($footnotesWrapper);
}
}
/**
* Reverts P elements with class 'readability-styled'
* to text nodes - which is what they were before.
*
* @param DOMElement
* @return void
*/
function revertReadabilityStyledElements($articleContent) {
$xpath = new DOMXPath($articleContent->ownerDocument);
$elems = $xpath->query('.//p[@class="readability-styled"]', $articleContent);
//$elems = $articleContent->getElementsByTagName('p');
for ($i = $elems->length-1; $i >= 0; $i--) {
$e = $elems->item($i);
$e->parentNode->replaceChild($articleContent->ownerDocument->createTextNode($e->textContent), $e);
//if ($e->hasAttribute('class') && $e->getAttribute('class') == 'readability-styled') {
// $e->parentNode->replaceChild($this->dom->createTextNode($e->textContent), $e);
//}
}
}
/**
* Prepare the article node for display. Clean out any inline styles,
* iframes, forms, strip extraneous <p> tags, etc.
*
* @param DOMElement
* @return void
*/
function prepArticle($articleContent) {
$this->cleanStyles($articleContent);
$this->killBreaks($articleContent);
if ($this->revertForcedParagraphElements) {
$this->revertReadabilityStyledElements($articleContent);
}
/* Clean out junk from the article content */
$this->cleanConditionally($articleContent, 'form');
$this->clean($articleContent, 'input');
$this->clean($articleContent, 'button');
$this->clean($articleContent, 'h1');
/**
* If there is only one h2, they are probably using it
* as a header and not a subheader, so remove it since we already have a header.
***/
if ($articleContent->getElementsByTagName('h2')->length == 1) {
$this->clean($articleContent, 'h2');
}
$this->cleanHeaders($articleContent);
/* Do these last as the previous stuff may have removed junk that will affect these */
$this->cleanConditionally($articleContent, 'table');
$this->cleanConditionally($articleContent, 'ul');
$this->cleanConditionally($articleContent, 'div');
/* Remove extra paragraphs */
$articleParagraphs = $articleContent->getElementsByTagName('p');
for ($i = $articleParagraphs->length-1; $i >= 0; $i--)
{
$imgCount = $articleParagraphs->item($i)->getElementsByTagName('img')->length;
$embedCount = $articleParagraphs->item($i)->getElementsByTagName('embed')->length;
$iframeCount = $articleParagraphs->item($i)->getElementsByTagName('iframe')->length;
$objectCount = $articleParagraphs->item($i)->getElementsByTagName('object')->length;
if ($imgCount === 0 && $iframeCount === 0 && $embedCount === 0 && $objectCount === 0 && $this->getInnerText($articleParagraphs->item($i), false) == '')
{
$articleParagraphs->item($i)->parentNode->removeChild($articleParagraphs->item($i));
}
}
}
/**
* Initialize a node with the readability object. Also checks the
* className/id for special names to add to its score.
*
* @param Element
* @return void
**/
protected function initializeNode($node) {
$readability = $this->dom->createAttribute('readability');
$readability->value = 0; // this is our contentScore
$node->setAttributeNode($readability);
switch (strtoupper($node->tagName)) { // unsure if strtoupper is needed, but using it just in case
case 'DIV':
$readability->value += 5;
break;
case 'PRE':
case 'TD':
case 'BLOCKQUOTE':
$readability->value += 3;
break;
case 'ADDRESS':
case 'OL':
case 'UL':
case 'DL':
case 'DD':
case 'DT':
case 'LI':
case 'FORM':
$readability->value -= 3;
break;
case 'H1':
case 'H2':
case 'H3':
case 'H4':
case 'H5':
case 'H6':
case 'TH':
$readability->value -= 5;
break;
}
$readability->value += $this->getClassWeight($node);
}
/***
* grabArticle - Using a variety of metrics (content score, classname, element types), find the content that is
* most likely to be the stuff a user wants to read. Then return it wrapped up in a div.
*
* @return DOMElement
**/
protected function grabArticle($page=null) {
$stripUnlikelyCandidates = $this->flagIsActive(self::FLAG_STRIP_UNLIKELYS);
if (!$page) $page = $this->dom;
$allElements = $page->getElementsByTagName('*');
/**
* First, node prepping. Trash nodes that look cruddy (like ones with the class name "comment", etc), and turn divs
* into P tags where they have been used inappropriately (as in, where they contain no other block level elements.)
*
* Note: Assignment from index for performance. See http://www.peachpit.com/articles/article.aspx?p=31567&seqNum=5
* TODO: Shouldn't this be a reverse traversal?
**/
$node = null;
$nodesToScore = array();
for ($nodeIndex = 0; ($node = $allElements->item($nodeIndex)); $nodeIndex++) {
//for ($nodeIndex=$targetList->length-1; $nodeIndex >= 0; $nodeIndex--) {
//$node = $targetList->item($nodeIndex);
$tagName = strtoupper($node->tagName);
/* Remove unlikely candidates */
if ($stripUnlikelyCandidates) {
$unlikelyMatchString = $node->getAttribute('class') . $node->getAttribute('id');
if (
preg_match($this->regexps['unlikelyCandidates'], $unlikelyMatchString) &&
!preg_match($this->regexps['okMaybeItsACandidate'], $unlikelyMatchString) &&
$tagName != 'BODY'
)
{
$this->dbg('Removing unlikely candidate - ' . $unlikelyMatchString);
//$nodesToRemove[] = $node;
$node->parentNode->removeChild($node);
$nodeIndex--;
continue;
}
}
if ($tagName == 'P' || $tagName == 'TD' || $tagName == 'PRE') {
$nodesToScore[] = $node;
}
if ($tagName == 'IFRAME') {
if (preg_match($this->regexps['video'], $node->getAttribute('src'))) {
$nodesToScore[] = $node;
} else {
$node->parentNode->removeChild($node);
$nodeIndex--;
continue;
}
}
/* Turn all divs that don't have children block level elements into p's */
if ($tagName == 'DIV') {
if (!preg_match($this->regexps['divToPElements'], $node->innerHTML)) {
$this->dbg('Altering div to p');
$newNode = $this->dom->createElement('p');
try {
$newNode->innerHTML = $node->innerHTML;
//$nodesToReplace[] = array('new'=>$newNode, 'old'=>$node);
$node->parentNode->replaceChild($newNode, $node);
$nodeIndex--;
$nodesToScore[] = $node; // or $newNode?
}
catch(Exception $e) {
$this->dbg('Could not alter div to p, reverting back to div.: ' . $e);
}
}
else
{
/* EXPERIMENTAL */
// TODO: change these p elements back to text nodes after processing
for ($i = 0, $il = $node->childNodes->length; $i < $il; $i++) {
$childNode = $node->childNodes->item($i);
if ($childNode->nodeType == 3) { // XML_TEXT_NODE
$this->dbg('replacing text node with a p tag with the same content.');
$p = $this->dom->createElement('p');
$p->innerHTML = $childNode->nodeValue;
$p->setAttribute('style', 'display: inline;');
$p->setAttribute('class', 'readability-styled');
$childNode->parentNode->replaceChild($p, $childNode);
}
}
}
}
}
/**
* Loop through all paragraphs, and assign a score to them based on how content-y they look.
* Then add their score to their parent node.
*
* A score is determined by things like number of commas, class names, etc. Maybe eventually link density.
**/
$candidates = array();
for ($pt=0; $pt < count($nodesToScore); $pt++) {
$parentNode = $nodesToScore[$pt]->parentNode;
// $grandParentNode = $parentNode ? $parentNode->parentNode : null;
$grandParentNode = !$parentNode ? null : (($parentNode->parentNode instanceof DOMElement) ? $parentNode->parentNode : null);
$innerText = $this->getInnerText($nodesToScore[$pt]);
if (!$parentNode || !isset($parentNode->tagName)) {
continue;
}
/* If this paragraph is less than 25 characters, don't even count it. */
if(strlen($innerText) < 25) {
continue;
}
/* Initialize readability data for the parent. */
if (!$parentNode->hasAttribute('readability'))
{
$this->initializeNode($parentNode);
$candidates[] = $parentNode;
}
/* Initialize readability data for the grandparent. */
if ($grandParentNode && !$grandParentNode->hasAttribute('readability') && isset($grandParentNode->tagName))
{
$this->initializeNode($grandParentNode);
$candidates[] = $grandParentNode;
}
$contentScore = 0;
/* Add a point for the paragraph itself as a base. */
$contentScore++;
/* Add points for any commas within this paragraph */
$contentScore += count(explode(',', $innerText));
/* For every 100 characters in this paragraph, add another point. Up to 3 points. */
$contentScore += min(floor(strlen($innerText) / 100), 3);
/* Add the score to the parent. The grandparent gets half. */
$parentNode->getAttributeNode('readability')->value += $contentScore;
if ($grandParentNode) {
$grandParentNode->getAttributeNode('readability')->value += $contentScore/2;
}
}
/**
* After we've calculated scores, loop through all of the possible candidate nodes we found
* and find the one with the highest score.
**/
$topCandidate = null;
for ($c=0, $cl=count($candidates); $c < $cl; $c++)
{
/**
* Scale the final candidates score based on link density. Good content should have a
* relatively small link density (5% or less) and be mostly unaffected by this operation.
**/
$readability = $candidates[$c]->getAttributeNode('readability');
$readability->value = $readability->value * (1-$this->getLinkDensity($candidates[$c]));
$this->dbg('Candidate: ' . $candidates[$c]->tagName . ' (' . $candidates[$c]->getAttribute('class') . ':' . $candidates[$c]->getAttribute('id') . ') with score ' . $readability->value);
if (!$topCandidate || $readability->value > (int)$topCandidate->getAttribute('readability')) {
$topCandidate = $candidates[$c];
}
}
/**
* If we still have no top candidate, just use the body as a last resort.
* We also have to copy the body node so it is something we can modify.
**/
if ($topCandidate === null || strtoupper($topCandidate->tagName) == 'BODY')
{
$topCandidate = $this->dom->createElement('div');
if ($page instanceof DOMDocument) {
if (!isset($page->documentElement)) {
// we don't have a body either? what a mess! :)
} else {
$topCandidate->innerHTML = $page->documentElement->innerHTML;
$page->documentElement->innerHTML = '';
$page->documentElement->appendChild($topCandidate);
}
} else {
$topCandidate->innerHTML = $page->innerHTML;
$page->innerHTML = '';
$page->appendChild($topCandidate);
}
$this->initializeNode($topCandidate);
}
/**
* Now that we have the top candidate, look through its siblings for content that might also be related.
* Things like preambles, content split by ads that we removed, etc.
**/
$articleContent = $this->dom->createElement('div');
$articleContent->setAttribute('id', 'readability-content');
$siblingScoreThreshold = max(10, ((int)$topCandidate->getAttribute('readability')) * 0.2);
$siblingNodes = $topCandidate->parentNode->childNodes;
if (!isset($siblingNodes)) {
$siblingNodes = new stdClass;
$siblingNodes->length = 0;
}
for ($s=0, $sl=$siblingNodes->length; $s < $sl; $s++)
{
$siblingNode = $siblingNodes->item($s);
$append = false;
$this->dbg('Looking at sibling node: ' . $siblingNode->nodeName . (($siblingNode->nodeType === XML_ELEMENT_NODE && $siblingNode->hasAttribute('readability')) ? (' with score ' . $siblingNode->getAttribute('readability')) : ''));
//dbg('Sibling has score ' . ($siblingNode->readability ? siblingNode.readability.contentScore : 'Unknown'));
if ($siblingNode === $topCandidate)
// or if ($siblingNode->isSameNode($topCandidate))
{
$append = true;
}
$contentBonus = 0;
/* Give a bonus if sibling nodes and top candidates have the example same classname */
if ($siblingNode->nodeType === XML_ELEMENT_NODE && $siblingNode->getAttribute('class') == $topCandidate->getAttribute('class') && $topCandidate->getAttribute('class') != '') {
$contentBonus += ((int)$topCandidate->getAttribute('readability')) * 0.2;
}
if ($siblingNode->nodeType === XML_ELEMENT_NODE && $siblingNode->hasAttribute('readability') && (((int)$siblingNode->getAttribute('readability')) + $contentBonus) >= $siblingScoreThreshold)
{
$append = true;
}
if (strtoupper($siblingNode->nodeName) == 'P') {
$linkDensity = $this->getLinkDensity($siblingNode);
$nodeContent = $this->getInnerText($siblingNode);
$nodeLength = strlen($nodeContent);
if ($nodeLength > 80 && $linkDensity < 0.25)
{
$append = true;
}
else if ($nodeLength < 80 && $linkDensity === 0 && preg_match('/\.( |$)/', $nodeContent))
{
$append = true;
}
}
if ($append)
{
$this->dbg('Appending node: ' . $siblingNode->nodeName);
$nodeToAppend = null;
$sibNodeName = strtoupper($siblingNode->nodeName);
if ($sibNodeName != 'DIV' && $sibNodeName != 'P') {
/* We have a node that isn't a common block level element, like a form or td tag. Turn it into a div so it doesn't get filtered out later by accident. */
$this->dbg('Altering siblingNode of ' . $sibNodeName . ' to div.');
$nodeToAppend = $this->dom->createElement('div');
try {
$nodeToAppend->setAttribute('id', $siblingNode->getAttribute('id'));
$nodeToAppend->innerHTML = $siblingNode->innerHTML;
}
catch(Exception $e)
{
$this->dbg('Could not alter siblingNode to div, reverting back to original.');
$nodeToAppend = $siblingNode;
$s--;
$sl--;
}
} else {
$nodeToAppend = $siblingNode;
$s--;
$sl--;
}
/* To ensure a node does not interfere with readability styles, remove its classnames */
$nodeToAppend->removeAttribute('class');
/* Append sibling and subtract from our list because it removes the node when you append to another node */
$articleContent->appendChild($nodeToAppend);
}
}
/**
* So we have all of the content that we need. Now we clean it up for presentation.
**/
$this->prepArticle($articleContent);
/**
* Now that we've gone through the full algorithm, check to see if we got any meaningful content.
* If we didn't, we may need to re-run grabArticle with different flags set. This gives us a higher
* likelihood of finding the content, and the sieve approach gives us a higher likelihood of
* finding the -right- content.
**/
if (strlen($this->getInnerText($articleContent, false)) < 250)
{
if (!isset($this->body->childNodes)) $this->body = $this->dom->createElement('body');
$this->body->innerHTML = $this->bodyCache;
if ($this->flagIsActive(self::FLAG_STRIP_UNLIKELYS)) {
$this->removeFlag(self::FLAG_STRIP_UNLIKELYS);
return $this->grabArticle($this->body);
}
else if ($this->flagIsActive(self::FLAG_WEIGHT_CLASSES)) {
$this->removeFlag(self::FLAG_WEIGHT_CLASSES);
return $this->grabArticle($this->body);
}
else if ($this->flagIsActive(self::FLAG_CLEAN_CONDITIONALLY)) {
$this->removeFlag(self::FLAG_CLEAN_CONDITIONALLY);
return $this->grabArticle($this->body);
}
else {
return false;
}
}
return $articleContent;
}
/**
* Remove script tags from document
*
* @param DOMElement
* @return void
*/
public function removeScripts($doc) {
$scripts = $doc->getElementsByTagName('script');
for($i = $scripts->length-1; $i >= 0; $i--)
{
$scripts->item($i)->parentNode->removeChild($scripts->item($i));
}
$linkTags = $this->dom->getElementsByTagName('link');
for ($i = $linkTags->length-1; $i >= 0; $i--)
{
$linkTags->item($i)->parentNode->removeChild($linkTags->item($i));
}
}
/**
* Get the inner text of a node.
* This also strips out any excess whitespace to be found.
*
* @param DOMElement $
* @param boolean $normalizeSpaces (default: true)
* @return string
**/
public function getInnerText($e, $normalizeSpaces=true) {
$textContent = '';
if (!isset($e->textContent) || $e->textContent == '') {
return '';
}
$textContent = trim($e->textContent);
if ($normalizeSpaces) {
return preg_replace($this->regexps['normalize'], ' ', $textContent);
} else {
return $textContent;
}
}
/**
* Get the number of times a string $s appears in the node $e.
*
* @param DOMElement $e
* @param string - what to count. Default is ","
* @return number (integer)
**/
public function getCharCount($e, $s=',') {
return substr_count($this->getInnerText($e), $s);
}
/**
* Remove the style attribute on every $e and under.
*
* @param DOMElement $e
* @return void
*/
public function cleanStyles($e) {
if (!is_object($e)) return;
$elems = $e->getElementsByTagName('*');
foreach ($elems as $elem) {
$elem->removeAttribute('style');
}
}
/**
* Get the density of links as a percentage of the content
* This is the amount of text that is inside a link divided by the total text in the node.
*
* @param DOMElement $e
* @return number (float)
*/
public function getLinkDensity($e) {
$links = $e->getElementsByTagName('a');
$textLength = strlen($this->getInnerText($e));
$linkLength = 0;
for ($i=0, $il=$links->length; $i < $il; $i++)
{
$linkLength += strlen($this->getInnerText($links->item($i)));
}
if ($textLength > 0) {
return $linkLength / $textLength;
} else {
return 0;
}
}
/**
* Get an elements class/id weight. Uses regular expressions to tell if this
* element looks good or bad.
*
* @param DOMElement $e
* @return number (Integer)
*/
public function getClassWeight($e) {
if(!$this->flagIsActive(self::FLAG_WEIGHT_CLASSES)) {
return 0;
}
$weight = 0;
/* Look for a special classname */
if ($e->hasAttribute('class') && $e->getAttribute('class') != '')
{
if (preg_match($this->regexps['negative'], $e->getAttribute('class'))) {
$weight -= 25;
}
if (preg_match($this->regexps['positive'], $e->getAttribute('class'))) {
$weight += 25;
}
}
/* Look for a special ID */
if ($e->hasAttribute('id') && $e->getAttribute('id') != '')
{
if (preg_match($this->regexps['negative'], $e->getAttribute('id'))) {
$weight -= 25;
}
if (preg_match($this->regexps['positive'], $e->getAttribute('id'))) {
$weight += 25;
}
}
return $weight;
}
/**
* Remove extraneous break tags from a node.
*
* @param DOMElement $node
* @return void
*/
public function killBreaks($node) {
$html = $node->innerHTML;
$html = preg_replace($this->regexps['killBreaks'], '<br />', $html);
$node->innerHTML = $html;
}
/**
* Clean a node of all elements of type "tag".
* (Unless it's a youtube/vimeo video. People love movies.)
*
* @param DOMElement $e
* @param string $tag
* @return void
*/
public function clean($e, $tag) {
$targetList = $e->getElementsByTagName($tag);
$isEmbed = ($tag == 'object' || $tag == 'embed' || $tag == 'iframe');
for ($y=$targetList->length-1; $y >= 0; $y--) {
/* Allow youtube and vimeo videos through as people usually want to see those. */
if ($isEmbed) {
$attributeValues = '';
for ($i=0, $il=$targetList->item($y)->attributes->length; $i < $il; $i++) {
$attributeValues .= $targetList->item($y)->attributes->item($i)->value . '|'; // DOMAttr? (TODO: test)
}
/* First, check the elements attributes to see if any of them contain youtube or vimeo */
if (preg_match($this->regexps['video'], $attributeValues)) {
continue;
}
/* Then check the elements inside this element for the same. */
if (preg_match($this->regexps['video'], $targetList->item($y)->innerHTML)) {
continue;
}
}
$targetList->item($y)->parentNode->removeChild($targetList->item($y));
}
}
/**
* Clean an element of all tags of type "tag" if they look fishy.
* "Fishy" is an algorithm based on content length, classnames,
* link density, number of images & embeds, etc.
*
* @param DOMElement $e
* @param string $tag
* @return void
*/
public function cleanConditionally($e, $tag) {
if (!$this->flagIsActive(self::FLAG_CLEAN_CONDITIONALLY)) {
return;
}
$tagsList = $e->getElementsByTagName($tag);
$curTagsLength = $tagsList->length;
/**
* Gather counts for other typical elements embedded within.
* Traverse backwards so we can remove nodes at the same time without effecting the traversal.
*
* TODO: Consider taking into account original contentScore here.
*/
for ($i=$curTagsLength-1; $i >= 0; $i--) {
$weight = $this->getClassWeight($tagsList->item($i));
$contentScore = ($tagsList->item($i)->hasAttribute('readability')) ? (int)$tagsList->item($i)->getAttribute('readability') : 0;
$this->dbg('Cleaning Conditionally ' . $tagsList->item($i)->tagName . ' (' . $tagsList->item($i)->getAttribute('class') . ':' . $tagsList->item($i)->getAttribute('id') . ')' . (($tagsList->item($i)->hasAttribute('readability')) ? (' with score ' . $tagsList->item($i)->getAttribute('readability')) : ''));
if ($weight + $contentScore < 0) {
$tagsList->item($i)->parentNode->removeChild($tagsList->item($i));
}
else if ( $this->getCharCount($tagsList->item($i), ',') < 10) {
/**
* If there are not very many commas, and the number of
* non-paragraph elements is more than paragraphs or other ominous signs, remove the element.
**/
$p = $tagsList->item($i)->getElementsByTagName('p')->length;
$img = $tagsList->item($i)->getElementsByTagName('img')->length;
$li = $tagsList->item($i)->getElementsByTagName('li')->length-100;
$input = $tagsList->item($i)->getElementsByTagName('input')->length;
$embedCount = 0;
$embeds = $tagsList->item($i)->getElementsByTagName('embed');
for ($ei=0, $il=$embeds->length; $ei < $il; $ei++) {
if (preg_match($this->regexps['video'], $embeds->item($ei)->getAttribute('src'))) {
$embedCount++;
}
}
$linkDensity = $this->getLinkDensity($tagsList->item($i));
$contentLength = strlen($this->getInnerText($tagsList->item($i)));
$toRemove = false;
if ($li > $p && $tag != 'ul' && $tag != 'ol') {
$toRemove = true;
} else if ( $input > floor($p/3) ) {
$toRemove = true;
} else if ($contentLength < 25 && ($img === 0 || $img > 2) ) {
$toRemove = true;
} else if($weight < 25 && $linkDensity > 0.2) {
$toRemove = true;
} else if($weight >= 25 && $linkDensity > 0.5) {
$toRemove = true;
} else if(($embedCount == 1 && $contentLength < 75) || $embedCount > 1) {
$toRemove = true;
}
if ($toRemove) {
$tagsList->item($i)->parentNode->removeChild($tagsList->item($i));
}
}
}
}
/**
* Clean out spurious headers from an Element. Checks things like classnames and link density.
*
* @param DOMElement $e
* @return void
*/
public function cleanHeaders($e) {
for ($headerIndex = 1; $headerIndex < 3; $headerIndex++) {
$headers = $e->getElementsByTagName('h' . $headerIndex);
for ($i=$headers->length-1; $i >=0; $i--) {
if ($this->getClassWeight($headers->item($i)) < 0 || $this->getLinkDensity($headers->item($i)) > 0.33) {
$headers->item($i)->parentNode->removeChild($headers->item($i));
}
}
}
}
public function flagIsActive($flag) {
return ($this->flags & $flag) > 0;
}
public function addFlag($flag) {
$this->flags = $this->flags | $flag;
}
public function removeFlag($flag) {
$this->flags = $this->flags & ~$flag;
}
}
?>