private static $status_code = 200;

private static $status_header;

private static $static = static_cache;

private static $memory = memory_cache;

private static $nocache = false;

private static $started = false;

private static $host;

/**

* disable()

*

* @param mixed $in

* @return mixed $in

**/

static function disable($in = null) {

self::$nocache = true;

return $in;

} # disable()

/**

* status_header()

*

* @param string $status_header

* @param int $status_code

* @return string $status_header

**/

static function status_header($status_header, $status_code) {

self::$status_code = (int) $status_code;

self::$status_header = $status_header;

return $status_header;

} # status_header()

/**

* wp_redirect_status()

*

* @param int $status_code

* @return int $status_code

**/

static function wp_redirect_status($status_code) {

$text = get_status_header_desc($status_code);

$protocol = $_SERVER["SERVER_PROTOCOL"];

if ( 'HTTP/1.1' != $protocol && 'HTTP/1.0' != $protocol )

$protocol = 'HTTP/1.0';

$status_header = "$protocol $status_code $text";

if ( function_exists('apply_filters') )

$status_header = apply_filters('status_header', $status_header, $status_code, $text, $protocol);

return $status_code;

} # wp_redirect_status()

/**

* send_headers()

*

* @param array $headers

* @return void

**/

static function send_headers($headers) {

$bail = false;

$server_etag = false;

$client_etag = !empty($_SERVER['HTTP_IF_NONE_MATCH'])

? trim(strip_tags(stripslashes($_SERVER['HTTP_IF_NONE_MATCH'])))

: $req_etag = false;

$server_modified = false;

$client_modified = !empty($_SERVER['HTTP_IF_MODIFIED_SINCE'])

? trim($_SERVER['HTTP_IF_MODIFIED_SINCE'])

: '';

if ( $client_etag || $client_modified ) {

foreach ( $headers as $header ) {

list($k, $v) = array_merge( preg_split("/:\s*/", $header), '');

switch ( strtolower($k) ) {

case 'etag':

$server_etag = trim(strip_tags($v));

break;

case 'last-modified':

$server_modified = trim($v);

}

}

}

if ( $client_etag && $server_etag || $client_modified && $server_modified ) {

if ( $client_modified && $server_modified ) {

$client_modified = strtotime($client_modified);

$server_modified = strtotime($server_modified);

}

if ( $client_etag && $server_etag && $client_modified && $server_modified ) {

$bail = ( $client_etag == $server_etag ) && ( $client_modified >= $server_modified );

} elseif ( $client_etag && $server_etag ) {

$bail = ( $client_etag == $server_etag );

} elseif ( $client_modified && $server_modified ) {

$bail = ( $client_modified >= $server_modified );

}

}

foreach ( $headers as $header )

header($header, true);

if ( $bail ) {

$protocol = $_SERVER["SERVER_PROTOCOL"];

if ( 'HTTP/1.1' != $protocol && 'HTTP/1.0' != $protocol )

$protocol = 'HTTP/1.0';

header("$protocol 304 Not Modified", true, 304);

die;

}

} # send_headers()

/**

* start()

*

* @return void

**/

static function start() {

# some things can be taken care of at all times

switch ( basename($_SERVER['REQUEST_URI']) ) {

case 'favicon.ico':

# bypass WP entirely on favicon.ico

$protocol = $_SERVER["SERVER_PROTOCOL"];

if ( 'HTTP/1.1' != $protocol && 'HTTP/1.0' != $protocol )

$protocol = 'HTTP/1.0';

$headers = array(

"$protocol 404 Not Found",

'Expires: Wed, 11 Jan 1984 05:00:00 GMT',

'Last-Modified: ' . gmdate( 'D, d M Y H:i:s' ) . ' GMT',

'Cache-Control: no-cache, must-revalidate, max-age=0',

'Pragma: no-cache',

'Content-Type: image/x-icon',

);

foreach ( $headers as $header )

header($header, true);

die;

case 'sitemap.xml':

case 'sitemap.xml.gz':

case 'sitemap_index.xml':

# let xml sitemap plugins cache themselves

return;

}

global $sem_cache_cookies;

if ( ( !defined('WP_CACHE') || !WP_CACHE )

|| isset($_GET['action']) || isset($_GET['doing_wp_cron'])

|| isset($_GET['debug']) || isset($_GET['preview'])

|| ( defined('WP_INSTALLING') && WP_INSTALLING )

|| ( defined('WP_ADMIN') && WP_ADMIN )

|| ( defined('DOING_CRON') && DOING_CRON )

|| ( defined('DOING_AJAX') && DOING_AJAX )

|| $_POST || !$sem_cache_cookies

|| array_intersect(array_keys($_COOKIE), (array) $sem_cache_cookies)

|| self::$nocache

)

return;

# kill static cache on multisite installs

self::$static &= !( function_exists('is_multisite') && is_multisite() );

if ( self::$started || headers_sent() || !self::$static && !self::$memory )

return;

if ( isset($_SERVER['HTTPS']) && ( 'on' == strtolower($_SERVER['HTTPS']) || '1' == $_SERVER['HTTPS'] ) || isset($_SERVER['SERVER_PORT']) && ( '443' == $_SERVER['SERVER_PORT'] ) ) {

self::$host = 'https://' . $_SERVER['HTTP_HOST'];

} else {

self::$host = 'http://' . $_SERVER['HTTP_HOST'];

}

$cache_id = self::$host . preg_replace("/#.*/", '', $_SERVER['REQUEST_URI']);

$cache_id = md5($cache_id);

if ( self::$memory ) {

$headers = wp_cache_get($cache_id, 'cached_headers');

if ( $headers !== false ) {

self::send_headers($headers);

$buffer = wp_cache_get($cache_id, 'cached_buffers');

if ( $buffer )

echo $buffer;

die;

}

} elseif ( !( function_exists('is_multisite') && is_multisite() ) ) {

# poor man's memcached

$headers = '/semi-static/' . $cache_id . '.meta';

if ( cache_fs::exists($headers, cache_timeout) ) {

$headers = unserialize(cache_fs::get_contents($headers));

self::send_headers($headers);

$buffer = '/semi-static/' . $cache_id . '.html';

if ( cache_fs::exists($buffer) )

cache_fs::readfile($buffer);

die;

}

}

self::$started = true;

ob_start(array('static_cache', 'ob_callback'));

} # start()

/**

* ob_callback()

*

* @param string $buffer

* @return string $buffer

**/

static function ob_callback($buffer) {

if ( !class_exists('sem_cache') )

return $buffer;

if ( DONOTCACHEPAGE )

return $buffer;

# some things just shouldn't be cached

if ( self::$nocache && !in_array(self::$status_code, array(301, 302, 404))

|| !in_array(self::$status_code, array(200, 301, 302, 404)) ) {

return $buffer;

}

# sanity check on cookies

global $sem_cache_cookies;

if ( !$sem_cache_cookies || $sem_cache_cookies != sem_cache::get_cookies() )

return $buffer;

# only cache visitor requests

if ( array_intersect(array_keys($_COOKIE), $sem_cache_cookies) )

return $buffer;

# bail on valid but rarely served pages

if ( self::$status_code == 200

&& !(

# post or page

!is_feed() && is_singular()

# first page of blog or category

|| !is_feed() && ( is_home() || is_category() ) && !is_paged()

# blog and category feed

|| is_feed() && ( !is_archive() && !is_singular() /* home feed */ || is_category() )

) ) {

return $buffer;

}

// let's see if this page is excluded

$exclude_pages = get_site_option( 'sem_cache_excluded_pages', '' );

if ( ! empty ( $exclude_pages ) ) {

$exclude_pages = explode( ' ', $exclude_pages );

$request_uri = $_SERVER['REQUEST_URI'];

$request_uri = parse_url( $request_uri, PHP_URL_PATH );

if ( in_array( $request_uri, $exclude_pages) )

return $buffer;

}

// and no point caching querystring requests since htaccess ignores those

/* $request_uri = $_SERVER['REQUEST_URI'];

$querystring = parse_url( $request_uri, PHP_URL_QUERY );

if ( $querystring !== NULL )

return $buffer;

*/

#don't cache a contact form page due to spam prevention techniques

// if ( preg_match("/(\bsem_contact_form\b)/i",$buffer) )

// return $buffer;

#don't cache a page due if a sem_no_cache flag is found. Provide manual way to exclude a page

if ( preg_match("/(\bsem_do_not_cache\b)/i",$buffer) )

return $buffer;

$permalink_structure = get_option('permalink_structure');

# statically cache only when relevant

self::$static &= ( strpos($_SERVER['REQUEST_URI'], './') === false )

&& ( self::$status_code == 200 )

&& !is_feed()

&& empty($_GET)

&& $permalink_structure

&& ( strpos($permalink_structure, "|/index\.php/|") === false );

# sanity check on the base folder

$host = get_option('home');

// check if we're on a dev site

if( strpos( $host, 'localhost') === false ) {

if ( preg_match( "|^([^/]+://[^/]+)/|", $host, $_host ) ) {

$host = end( $_host );

}

if ( $host != self::$host ) {

return $buffer;

}

}

# sanity check on incomplete files

if ( !in_array(self::$status_code, array(301, 302)) && !preg_match("/(?:<\/html>|<\/rss>|<\/feed>)/i",$buffer) )

return $buffer;

# sanity check on mobile users

/* global $sem_mobile_agents;

if ( $sem_mobile_agents != sem_cache::get_mobile_agents() )

return $buffer;

$mobile_agents = $sem_mobile_agents;

// $mobile_agents = array_map('preg_quote', (array) $mobile_agents);

$mobile_agents = implode("|", $mobile_agents);

if ( preg_match("{($mobile_agents)}i", $_SERVER['HTTP_USER_AGENT']) )

return $buffer;

if ( preg_match("/(?=.*?\bandroid\b)(?=.*?\bmobile\b).*$/i", $_SERVER['HTTP_USER_AGENT']) )

return $buffer;

*/

// made it through all the checks. Let's minify the html now

$buffer = self::minify_html( $buffer );

if ( self::$static ) {

$file = preg_replace("/#.*/", '', $_SERVER['REQUEST_URI']);

$file = '/static/' . trim($file, '/');

if ( !preg_match("/\.html$/", $file) ) {

global $wp_rewrite;

if ( $wp_rewrite->use_trailing_slashes )

$file = $file . '/index.html';

else

$file = $file . '.html';

}

cache_fs::put_contents($file, $buffer);

} elseif ( self::$memory ) {

$cache_id = $host . preg_replace("/#.*/", '', $_SERVER['REQUEST_URI']);

$cache_id = md5($cache_id);

$headers = headers_list();

if ( self::$status_header )

array_unshift($headers, self::$status_header);

wp_cache_add($cache_id, $headers, 'cached_headers', cache_timeout);

if ( $buffer && !in_array(self::$status_code, array(301, 302)) )

wp_cache_add($cache_id, $buffer, 'cached_buffers', cache_timeout);

} elseif ( !( function_exists('is_multisite') && is_multisite() ) ) {

# poor man's memcached

$cache_id = $host . preg_replace("/#.*/", '', $_SERVER['REQUEST_URI']);

$cache_id = md5($cache_id);

$file = '/semi-static/' . $cache_id;

$headers = headers_list();

if ( self::$status_header )

array_unshift($headers, self::$status_header);

cache_fs::put_contents($file . '.meta', serialize($headers));

if ( $buffer && !in_array(self::$status_code, array(301, 302)) )

cache_fs::put_contents($file . '.html', $buffer);

}

return $buffer;

} # ob_callback()

/**

* minify_html()

*

* @param string $buffer

* @return string $buffer

**/

static function minify_html($buffer) {

// props: http://stackoverflow.com/questions/5312349/minifying-final-html-output-using-regular-expressions-with-codeigniter

ini_set("pcre.recursion_limit", "524");

$re = '%# Collapse ws everywhere but in blacklisted elements.

(?> # Match all whitespans other than single space.

[^\S ]\s* # Either one [\t\r\n\f\v] and zero or more ws,

| \s{2,} # or two or more consecutive-any-whitespace.

) # Note: The remaining regex consumes no text at all...

(?= # Ensure we are not in a blacklist tag.

(?: # Begin (unnecessary) group.

(?: # Zero or more of...

[^<]++ # Either one or more non-"<"

| < # or a < starting a non-blacklist tag.

(?!/?(?:textarea|pre)\b)

)*+ # (This could be "unroll-the-loop"ified.)

) # End (unnecessary) group.

(?: # Begin alternation group.

< # Either a blacklist start tag.

(?>textarea|pre)\b

| \z # or end of file.

) # End alternation group.

) # If we made it here, we are not in a blacklist tag.

%ix';

$buffer = preg_replace($re, " ", $buffer);

// $buffer = preg_replace("/^\s+/m", "", $buffer);

return $buffer;

} #minify_html()