lib/AkClassExtender.php

   1 <?php
   2
   3
   4 defined('AK_CLASS_EXTENDER_ENABLE_CACHE') ? null : define('AK_CLASS_EXTENDER_ENABLE_CACHE', !AK_DEV_MODE);
   5 /**
   6  * @ WARNING too experimental. This is a proof of concept. Do not use it for production.
   7  *
   8  * The AkClassExtender provides the means for extending core Akelos Framework
   9  * functionality by chaining multiple objects and creating an extended
  10  * composite class of the original.
  11  *
  12  * It is a good practice maintaining the level of parents low when writing OO
  13  * code, but PHP classes are closed and do not allow runtime modification so
  14  * this method will allow others to write core extensions that modify the default
  15  * Akelos Framework behavior.
  16  *
  17  * This technique requires that the participants of the class chain are not included yet
  18  * during execution, ass participants code will be joined, modified and cached for
  19  * including it as a single source file.
  20  */
  21 class AkClassExtender
  22 {
  23     var $_extended_classes;
  24
  25     function extendClassWithSource($class_name_to_extend, $extension_path, $priority = 10)
  26     {
  27         $this->_extended_classes[$class_name_to_extend][$priority][] = $extension_path;
  28     }
  29
  30     function _getExtensionFilePaths($class_name_to_extend)
  31     {
  32         $extension_files = array();
  33         if(!empty($this->_extended_classes[$class_name_to_extend])){
  34             $extensions = $this->_extended_classes[$class_name_to_extend];
  35             ksort($extensions);
  36             foreach ($extensions as $files){
  37                 $extension_files = array_merge($extension_files, $files);
  38             }
  39         }
  40         return $extension_files;
  41     }
  42
  43     function _getExtensionSourceAndChecksum($class_name_to_extend)
  44     {
  45         $file_contents = '';
  46         $file_paths = $this->_getExtensionFilePaths($class_name_to_extend);
  47         $checksum = md5(serialize($file_paths));
  48         if(!$this->_canIncludeMergedFile($class_name_to_extend, $checksum)){
  49             foreach ($file_paths as $file_path){
  50                 if(is_file($file_path)){
  51                     $file_contents .= Ak::file_get_contents($file_path);
  52                 }
  53             }
  54             return array($checksum, $file_contents);
  55         }else{
  56             return false;
  57         }
  58     }
  59
  60     function extendClasses()
  61     {
  62         foreach (array_keys($this->_extended_classes) as $class_name_to_extend){
  63             $this->makeClassExtensible($class_name_to_extend);
  64         }
  65     }
  66
  67     function makeClassExtensible($class_name_to_extend)
  68     {
  69         list($checksum, $source) = $this->_getExtensionSourceAndChecksum($class_name_to_extend);
  70         $merge_path = AK_TMP_DIR.DS.'.lib';
  71         if($source){
  72             if(preg_match_all('/[ \n\t]*([a-z]+)[ \n\t]*extends[ \n\t]*('.$class_name_to_extend.')[ \n\t]*[ \n\t]*{/i', $source, $matches)){
  73                 $replacements = array();
  74                 $extended_by = array();
  75
  76                 foreach ($matches[2] as $k => $class_to_extend){
  77                     if(empty($last_method) && class_exists($class_to_extend)){
  78                         $last_method = $class_to_extend;
  79                     }
  80                     if($class_to_extend == $last_method || !empty($extended_by[$class_to_extend]) && in_array($last_method,$extended_by[$class_to_extend])){
  81                         if(!class_exists($matches[1][$k])){
  82                             $replacements[trim($matches[0][$k],"\n\t {")] = $matches[1][$k].' extends '.$last_method;
  83                             $last_method = $matches[1][$k];
  84                             $extended_by[$class_to_extend][] = $last_method;
  85                         } else {
  86                             trigger_error(Ak::t('The class %class is already defined and can\'t be used for extending %parent_class', array('%class' => $matches[1][$k], '%parent_class' => $class_name_to_extend)), E_NOTICE);
  87                         }
  88                     }
  89                 }
  90                 $source = str_replace(array_keys($replacements), array_values($replacements), $source);
  91             }
  92             $source = "$source<?php class Extensible$class_name_to_extend extends $last_method{} ?>";
  93             if(md5($source) != @md5_file($merge_path.DS.'Extensible'.$class_name_to_extend.'.php')){
  94                 Ak::file_put_contents($merge_path.DS.'Extensible'.$class_name_to_extend.'.php', $source);
  95                 Ak::file_put_contents($merge_path.DS.'checksums'.DS.'Extensible'.$class_name_to_extend, $checksum);
  96             }
  97         }
  98
  99         include_once($merge_path.DS.'Extensible'.$class_name_to_extend.'.php');
 100     }
 101
 102     function _canIncludeMergedFile($class_name_to_extend, $checksum)
 103     {
 104         $merge_path = AK_TMP_DIR.DS.'.lib';
 105         if(AK_CLASS_EXTENDER_ENABLE_CACHE && file_exists($merge_path.DS.'Extensible'.$class_name_to_extend.'.php') &&
 106         Ak::file_get_contents($merge_path.DS.'checksums'.DS.'Extensible'.$class_name_to_extend) == $checksum){
 107             return true;
 108         }
 109         return false;
 110     }
 111 }
 112
 113
 114 ?>