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April 27, 2011 23:57
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Readability Port to php from http://www.keyvan.net/2010/08/php-readability/
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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: 2010-10-29 | |
* | |
* 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. | |
*/ | |
// This class allows us to do JavaScript like assignements to innerHTML | |
require_once(dirname(__FILE__).'/JSLikeHTMLElement.php'); | |
// Alternative usage (for testing only!) | |
// uncomment the lins below and call Readability.php in your browser | |
// passing it the URL of the page you'd like content from, e.g.: | |
// Readability.php?url=http://medialens.org/alerts/09/090615_the_guardian_climate.php | |
/* | |
if (!isset($_GET['url']) || $_GET['url'] == '') { | |
die('Please pass a URL to the script. E.g. Readability.php?url=bla.com/story.html'); | |
} | |
$url = $_GET['url']; | |
if (!preg_match('!^https?://!i', $url)) $url = 'http://'.$url; | |
$html = file_get_contents($url); | |
$r = new Readability($html, $url); | |
$r->init(); | |
echo $r->articleContent->innerHTML; | |
*/ | |
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 $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 $regexps = array( | |
'unlikelyCandidates' => '/combx|comment|community|disqus|extra|foot|header|menu|remark|rss|shoutbox|sidebar|sponsor|ad-break|agegate|pagination|pager|popup|tweet|twitter/i', | |
'okMaybeItsACandidate' => '/and|article|body|column|main|shadow/i', | |
'positive' => '/article|body|content|entry|hentry|main|page|pagination|post|text|blog|story/i', | |
'negative' => '/combx|comment|com-|contact|foot|footer|footnote|masthead|media|meta|outbrain|promo|related|scroll|shoutbox|sidebar|sponsor|shopping|tags|tool|widget/i', | |
'divToPElements' => '/<(a|blockquote|dl|div|img|ol|p|pre|table|ul)/i', | |
'replaceBrs' => '/(<br[^>]*>[ \n\r\t]*){2,}/i', | |
'replaceFonts' => '/<(\/?)font[^>]*>/i', | |
// 'trimRe' => '/^\s+|\s+$/g', // PHP has trim() | |
'normalize' => '/\s{2,}/', | |
'killBreaks' => '/(<br\s*\/?>(\s| ?)*){1,}/', | |
'video' => '/http:\/\/(www\.)?(youtube|vimeo)\.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) | |
{ | |
/* Turn all double br's into p's */ | |
/* Note, this is pretty costly as far as processing goes. Maybe optimize later. */ | |
$html = preg_replace($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; | |
$this->dom->registerNodeClass('DOMElement', 'JSLikeHTMLElement'); | |
@$this->dom->loadHTML($html); | |
$this->url = $url; | |
} | |
/** | |
* 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() | |
{ | |
$this->removeScripts($this->dom); | |
//die($this->getInnerHTML($this->dom->documentElement)); | |
// 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, Readability 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'); | |
$this->postProcessContent($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'); | |
$this->dom->documentElement->appendChild($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, '<$1span>'); | |
// We do this in the constructor for PHP as that's when we have raw HTML - before parsing it into a DOM tree. | |
// Manipulating innerHTML as it's done in JS is not possible in PHP. | |
} | |
/** | |
* For easier reading, convert this document to have footnotes at the bottom rather than inline links. | |
* @see http://www.roughtype.com/archives/2010/05/experiments_in.php | |
* | |
* @return void | |
**/ | |
public function addFootnotes($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, 'object'); | |
$this->clean($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'); | |
} | |
$this->clean($articleContent, 'iframe'); | |
$this->cleanHeaders($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; | |
$objectCount = $articleParagraphs->item($i)->getElementsByTagName('object')->length; | |
if ($imgCount === 0 && $embedCount === 0 && $objectCount === 0 && $this->getInnerText($articleParagraphs->item($i), false) == '') | |
{ | |
$articleParagraphs->item($i)->parentNode->removeChild($articleParagraphs->item($i)); | |
} | |
} | |
try { | |
$articleContent->innerHTML = preg_replace('/<br[^>]*>\s*<p/i', '<p', $articleContent->innerHTML); | |
//articleContent.innerHTML = articleContent.innerHTML.replace(/<br[^>]*>\s*<p/gi, '<p'); | |
} | |
catch (Exception $e) { | |
$this->dbg("Cleaning innerHTML of breaks failed. This is an IE strict-block-elements bug. Ignoring.: " . $e); | |
} | |
} | |
/** | |
* Initialize a node with the readability object. Also checks the | |
* className/id for special names to add to its score. | |
* | |
* @param Element | |
* @return void | |
**/ | |
protected function initializeNode($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[] = $node; | |
} | |
/* Turn all divs that don't have children block level elements into p's */ | |
if ($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'); | |
$topCandidate->innerHTML = ($page instanceof DOMDocument) ? $page->saveXML($page->documentElement) : $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 = $topCandidate->parentNode->childNodes; | |
for ($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) | |
{ | |
$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)); | |
} | |
} | |
/** | |
* 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) { | |
$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' || $tag == 'embed'); | |
for ($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 ( $img > $p ) { | |
$toRemove = true; | |
} else if ($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; | |
} | |
} | |
?> |
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