How to dynamically compress js and css files using PHP

<meta charset="utf-8"/>
<title>demo</title>
<?php
//定义需要压缩的文件
$css = array(
CSS_PATH . &#39;base.css&#39;,
CSS_PATH . &#39;style.css&#39;,
CSS_PATH . &#39;my.css&#39;
);
$js = array(
PUB_PATH . &#39;/lib/zepto.min.js&#39;,
PUB_PATH . &#39;/js/1.js&#39;,
JS_PATH . &#39;2.js&#39;,
);
$css_path = base_url(parse_css($css));
$js_path = base_url(parse_script($js));
?>
<link rel="stylesheet" type="text/css" href="<?php echo $css_path ?>" rel="external nofollow" >
<script src="<?php echo $js_path ?>"></script>
<!--下面可以继续放不能压缩或者不想压缩的文件-->
<script src="http://res.wx.qq.com/open/js/jweixin-1.0.0.js"></script>

4e387d5edce14cc2bd6396f6ebb7921b.css
7c10211f113f3175489196d336d67734.js

/**
*  合并压缩css
*/
function parse_css($urls)
{
  $url = md5(implode(',', $urls));
  $path = FCPATH. 'static/parse/';
  $css_url = $path . $url . '.css';
  if (!file_exists($css_url)) {
    if (!file_exists($path))
      mkdir($path, 0777);
    $css_content = '';
    foreach ($urls as $url) {
      $css_content .= @file_get_contents($url);
    }
    $css_content = str_replace("\r\n", '', $css_content); //清除换行符
    $css_content = str_replace("\n", '', $css_content); //清除换行符
    $css_content = str_replace("\t", '', $css_content); //清除制表符
    $css_content = str_replace("../images/", "./../common/images/", $css_content);
    @file_put_contents($css_url, $css_content);
  }
  $css_url = str_replace(FCPATH, '', $css_url);
  return $css_url;
}
/**
*  合并压缩js
*/
function parse_script($urls)
{
  $url = md5(implode(',', $urls));
  $path = FCPATH. '/static/parse/';
  $js_url = $path . $url . '.js';
  if (!file_exists($js_url)) {
    if (!file_exists($path))
      mkdir($path, 0777);
    load_qy_lib('JavaScriptPacker');
    $js_content = '';
    foreach ($urls as $url) {
      $append_content = @file_get_contents($url) . "\r\n";
      $packer = new JavaScriptPacker($append_content);
      $append_content = $packer->_basicCompression($append_content);
      $js_content .= $append_content;
    }
    @file_put_contents($js_url, $js_content);
  }
  $js_url = str_replace(FCPATH, '', $js_url);
  return $js_url;
}

/**
 * 9 April 2008. version 1.1
 *
 * This is the php version of the Dean Edwards JavaScript's Packer,
 * Based on :
 *
 * ParseMaster, version 1.0.2 (2005-08-19) Copyright 2005, Dean Edwards
 * a multi-pattern parser.
 * KNOWN BUG: erroneous behavior when using escapeChar with a replacement
 * value that is a function
 *
 * packer, version 2.0.2 (2005-08-19) Copyright 2004-2005, Dean Edwards
 *
 * License: http://creativecommons.org/licenses/LGPL/2.1/
 *
 * Ported to PHP by Nicolas Martin.
 *
 * ----------------------------------------------------------------------
 * changelog:
 * 1.1 : correct a bug, '\0' packed then unpacked becomes '\'.
 * ----------------------------------------------------------------------
 *
 * Changes:
 * 2014-08-28: grkalik: change class for composer support. no functionality change.
 *
 */