<?php
// File name:	xhtml.inc.php
// Description:	Extended PHP subroutine to read from/write to a file
// Date:	2004-12-29
// Author:	imacat <imacat@pristine.com.tw>
// Copyright:	Copyright (C) 2004-2007 Pristine Communications

// xhtml_content_type: Check whether application/xhtml+xml or text/html
//   should be sent to the client
function xhtml_content_type()
{
    // Browsers that claim to support application/xhtml+xml explicitly
    if (    array_key_exists("HTTP_ACCEPT", $_SERVER)
            && strpos($_SERVER["HTTP_ACCEPT"], "application/xhtml+xml") !== false) {
        return "application/xhtml+xml";
    }
    // Browsers that are known to support application/xhtml+xml
    if (array_key_exists("HTTP_USER_AGENT", $_SERVER)) {
        // W3C validator can recognize application/xhtml+xml
        if (substr($_SERVER["HTTP_USER_AGENT"], 0, 13) == "W3C_Validator") {
            return "application/xhtml+xml";
        }
    }
    // Else, we assume that application/xhtml+xml is not supported
    return "text/html";
}

?>