186 lines
6.7 KiB
PHP
186 lines
6.7 KiB
PHP
<?php
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/**
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* The content negotiator performs "text/html" or "application/xhtml+xml" switching.
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* It does this through the static function ContentNegotiator::process().
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* By default, ContentNegotiator will comply to the Accept headers the clients
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* sends along with the HTTP request, which is most likely "application/xhtml+xml"
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* (see "Order of selection" below).
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*
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* Order of selection between html or xhtml is as follows:
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* - if PHP has already sent the HTTP headers, default to "html" (we can't send HTTP Content-Type headers any longer)
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* - if a GET variable ?forceFormat is set, it takes precedence (for testing purposes)
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* - if the user agent is detected as W3C Validator we always deliver "xhtml"
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* - if an HTTP Accept header is sent from the client, we respect its order (this is the most common case)
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* - if none of the above matches, fallback is "html"
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*
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* ContentNegotiator doesn't enable you to send content as a true XML document
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* through the "text/xml" or "application/xhtml+xml" Content-Type.
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* Please see http://webkit.org/blog/68/understanding-html-xml-and-xhtml/ for further information.
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*
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* @package sapphire
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* @subpackage control
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*
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* @todo Check for correct XHTML doctype in xhtml()
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* @todo Allow for other HTML4 doctypes (e.g. Transitional) in html()
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* @todo Make content replacement and doctype setting two separately configurable behaviours - some
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* devs might know what they're doing and don't want contentnegotiator messing with their HTML4 doctypes,
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* but still find it useful to have self-closing tags removed.
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*/
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class ContentNegotiator {
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protected static $encoding = 'utf-8';
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protected static $enabled = false;
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/**
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* Set the character set encoding for this page. By default it's utf-8, but you could change it to, say, windows-1252, to
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* improve interoperability with extended characters being imported from windows excel.
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*/
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static function set_encoding($encoding) {
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self::$encoding = $encoding;
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}
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/**
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* Return the character encoding set bhy ContentNegotiator::set_encoding(). It's recommended that all classes that need to
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* specify the character set make use of this function.
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*/
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static function get_encoding() {
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return self::$encoding;
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}
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/**
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* Enable content negotiation for all templates, not just those with the xml header.
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*/
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static function enable() {
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self::$enabled = true;
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}
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/*
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* Disable content negotiation for all templates, not just those with the xml header.
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*/
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static function disable() {
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self::$enabled = false;
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}
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/**
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* Returns true if negotation is enabled for the given response.
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* By default, negotiation is only enabled for pages that have the xml header.
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*/
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static function enabled_for($response) {
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$contentType = $response->getHeader("Content-Type");
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// Disable content negotation for other content types
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if($contentType && substr($contentType, 0,9) != 'text/html' && substr($contentType, 0,21) != 'application/xhtml+xml') return false;
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if(self::$enabled) return true;
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else return (substr($response->getBody(),0,5) == '<' . '?xml');
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}
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static function process(SS_HTTPResponse $response) {
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if(!self::enabled_for($response)) return;
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$mimes = array(
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"xhtml" => "application/xhtml+xml",
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"html" => "text/html",
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);
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$q = array();
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if(headers_sent()) {
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$chosenFormat = "html";
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} else if(isset($_GET['forceFormat'])) {
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$chosenFormat = $_GET['forceFormat'];
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} else {
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// The W3C validator doesn't send an HTTP_ACCEPT header, but it can support xhtml. We put this special case in here so that
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// designers don't get worried that their templates are HTML4.
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if(isset($_SERVER['HTTP_USER_AGENT']) && substr($_SERVER['HTTP_USER_AGENT'], 0, 14) == 'W3C_Validator/') {
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$chosenFormat = "xhtml";
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} else {
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foreach($mimes as $format => $mime) {
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$regExp = '/' . str_replace(array('+','/'),array('\+','\/'), $mime) . '(;q=(\d+\.\d+))?/i';
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if (isset($_SERVER['HTTP_ACCEPT']) && preg_match($regExp, $_SERVER['HTTP_ACCEPT'], $matches)) {
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$preference = isset($matches[2]) ? $matches[2] : 1;
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if(!isset($q[$preference])) $q[$preference] = $format;
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}
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}
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if($q) {
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// Get the preferred format
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krsort($q);
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$chosenFormat = reset($q);
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} else {
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$chosenFormat = "html";
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}
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}
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}
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$negotiator = new ContentNegotiator();
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$negotiator->$chosenFormat( $response );
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}
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/**
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* Only sends the HTTP Content-Type as "application/xhtml+xml"
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* if the template starts with the typical "<?xml" Pragma.
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* Assumes that a correct doctype is set, and doesn't change or append to it.
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* Replaces a few common tags and entities with their XHTML representations (<br>, <img>, ).
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*
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* @param $response SS_HTTPResponse
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* @return string
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* @todo More flexible tag and entity parsing through regular expressions or tag definition lists
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*/
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function xhtml(SS_HTTPResponse $response) {
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$content = $response->getBody();
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// Only serve "pure" XHTML if the XML header is present
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if(substr($content,0,5) == '<' . '?xml' ) {
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$response->addHeader("Content-Type", "application/xhtml+xml; charset=" . self::$encoding);
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$response->addHeader("Vary" , "Accept");
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// Fix base tag
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$content = preg_replace('/<base href="([^"]*)"><!--\[if[[^\]*]\] \/><!\[endif\]-->/',
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'<base href="$1" />', $content);
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$content = str_replace(' ',' ', $content);
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$content = str_replace('<br>','<br />', $content);
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$content = eregi_replace('(<img[^>]*[^/>])>','\\1/>', $content);
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$response->setBody($content);
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} else {
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return $this->html($response);
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}
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}
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/*
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* Sends HTTP Content-Type as "text/html", and replaces existing doctypes with
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* HTML4.01 Strict.
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* Replaces self-closing tags like <img /> with unclosed solitary tags like <img>.
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* Replaces all occurrences of "application/xhtml+xml" with "text/html" in the template.
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* Removes "xmlns" attributes and any <?xml> Pragmas.
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*/
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function html(SS_HTTPResponse $response) {
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$response->addHeader("Content-Type", "text/html; charset=" . self::$encoding);
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$response->addHeader("Vary", "Accept");
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$content = $response->getBody();
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$hasXMLHeader = (substr($content,0,5) == '<' . '?xml' );
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// Fix base tag
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$content = preg_replace('/<base href="([^"]*)" \/>/',
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'<base href="$1"><!--[if lte IE 6]></base><![endif]-->', $content);
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$content = ereg_replace("<\\?xml[^>]+\\?>\n?",'',$content);
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$content = str_replace(array('/>','xml:lang','application/xhtml+xml'),array('>','lang','text/html'), $content);
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// Only replace the doctype in templates with the xml header
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if($hasXMLHeader) {
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$content = ereg_replace('<!DOCTYPE[^>]+>', '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">', $content);
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}
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$content = ereg_replace('<html xmlns="[^"]+"','<html ', $content);
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$response->setBody($content);
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}
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}
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