class cache
{
    var $cache_dir = './cache/';//This is the directory where the cache files will be stored;
    var $cache_time = 120;//How much time will keep the cache files in seconds.

    var $caching = false;
    var $file = '';

    function cache()
    {
    //Constructor of the class
    $this->file = $this->cache_dir . urlencode( $_SERVER['REQUEST_URI'] );
    if(file_exists($this->file)) $expired = $this->check_expire();
    else $expired = false;
    if ( file_exists ( $this->file ) && ( filemtime ( $this->file ) + $this->cache_time ) > time() && !$expired )
    {
        //Grab the cache:
        $handle = fopen( $this->file , "r");
        do {
        $data = fread($handle, 8192);
        if (strlen($data) == 0) {
            break;
        }
        echo $data;
        } while (true);
        fclose($handle);
        exit();
    }
    else
    {
        //create cache :
        $this->caching = true;
        ob_start();
        $now = time();
        echo "<!--last modified:".$now."-->\n";
    }
    }

    function close()
    {
    //You should have this at the end of each page
    if ( $this->caching )
    {
        //You were caching the contents so display them, and write the cache file
        $data = ob_get_clean();
        echo $data;
        $fp = fopen( $this->file , 'w' );
        fwrite ( $fp , $data );
        fclose ( $fp );
    }
    }
    function check_expire(){
    $fp = fopen($this->file,"r");
    preg_match("/\:([\d]+)\-/",fread($fp,200),$time);
    $modify_time = $time[1];
    if($modify_time<filemtime($_SERVER['SCRIPT_FILENAME'])){
        return true;
    }
    else{
        return false;
    }

    }
}
 

//Example :
$ch = new cache();
echo date("D M j G:i:s T Y");
$ch->close();