Analysis of common functions of Common/files in ThinkPHP

/**
  * Get and set configuration parameters Support batch definition
  * @param string|array $name configuration variable
  * @param mixed $value configuration value
  * @return mixed
  */
function C($name=null, $value=null) {
  static $_config = array();
  // Get all without parameters  if (empty($name)) {
    if(!empty($value) && $array = cache('c_'.$value)) {
      //array_change_key_case(): Change all key names in the array to all lowercase or uppercase, and the default will be changed to all lowercase      $_config = array_merge($_config, array_change_key_case($array));
    }
    return $_config;
  }
  // Priority is given to setting acquisition or assignment. If parameter 2 is empty, it is the case of obtaining the value of the configuration configuration variable; if parameter 2 is not empty, it is the case of setting the value of the configuration variable.  if (is_string($name)) {//Set the value of the configuration variable or get the value of the configuration variable    if (!strpos($name, '.')) {//If there is no "." in the configuration variable name, execute the following code      $name = strtolower($name);//Convert configuration variable name to lowercase      if (is_null($value))
        return isset($_config[$name]) ? $_config[$name] : null;//Get the configuration variable value and return the configuration variable value      $_config[$name] = $value;//Set values ​​for configuration variables      return;
    }
    // Two-dimensional array setting and obtain support    $name = explode('.', $name);
    $name[0]  = strtolower($name[0]);
    if (is_null($value))
      return isset($_config[$name[0]][$name[1]]) ? $_config[$name[0]][$name[1]] : null;//Stories of getting value    $_config[$name[0]][$name[1]] = $value;//Assignment situation    return;
  }
  // Batch setting  if (is_array($name)){//Batch setting value    //array_change_key_case(): Change all key names in the array to all lowercase or uppercase, the default will be changed to all lowercase. Note: Just change the key names to lowercase    $_config = array_merge($_config, array_change_key_case($name));
    if(!empty($value)) {// Save configuration values      cache('c_'.$value,$_config);
    }
    return;
  }
  return null; // Avoid illegal parameters}

/**
  * Process tag extensions, such as: call to the project start tag, tag('app_begin');
  * @param string $tag tag name
  * @param mixed $params Pass in parameters
  * @return mixed
  */
function tag($tag, &$params=NULL) {
  // System or framework tag extension  // C('extends', include THINK_PATH.'Conf/');//This file is very important  $extends  = C('extends.' . $tag);//$_config['extends'][app_init]
  // Application or project tag extension  // C('tags', include CONF_PATH.''); // You can also write your own files in the project  $tags    = C('tags.' . $tag);//$_config['tags'][app_init]
  if (!empty($tags)) {//If $tags is not empty    if(empty($tags['_overlay']) && !empty($extends)) { // Merge and expand      $tags = array_unique(array_merge($extends,$tags));
    }elseif(isset($tags['_overlay'])){ // Overwrite the system tag by setting '_overlay'=>1      unset($tags['_overlay']);
    }
  }elseif(!empty($extends)) {
    $tags = $extends;
  }
  if($tags) {
    if(APP_DEBUG) {
      G($tag.'Start');
      trace('[ '.$tag.' ] --START--','','INFO');
    }
    // Execute extension    foreach ($tags as $key=>$name) {
      if(!is_int($key)) { // Specify the full path to the behavior class for schema extension        $name  = $key;
      }
      //Create a behavior class object, such as: $class=$name.'Behavior';$behavior = new $class();//Create a behavior class object      B($name, $params);//Execute a certain behavior, parameter 1-behavior name Parameter 2-incoming parameters    }
    if(APP_DEBUG) { // Record the execution log of behavior      trace('[ '.$tag.' ] --END-- [ RunTime:'.G($tag.'Start',$tag.'End',6).'s ]','','INFO');
    }
  }else{ // No behavior is executed Return false    return false;
  }
}

/**
  * Perform a certain action
  * @param string $name behavior name
  * @param Mixed $params Parameters of the successor
  * @return void
  */
function B($name, &$params=NULL) {
  //The behavior class is automatically loaded in the autoload($class) function in the file  $class   = $name.'Behavior';//The name of the behavior class  G('behaviorStart');
  $behavior  = new $class();//Create a behavior class object  $behavior->run($params);//Pass parameters to the current behavioral object  if(APP_DEBUG) { // Record the execution log of behavior    trace('Run '.$name.' Behavior [ RunTime:'.G('behaviorStart','behaviorEnd',6).'s ]','','INFO');
  }
}

/**
 * The system automatically loads the ThinkPHP class library
 * And supports automatic loading path configuration
 * @param string $class object class name
 * @return void
 */
//Behavior classes, model classes, and controller classes are all automatically loaded through the autoload functionpublic static function autoload($class) {
    // Check if there is an alias definition    if(alias_import($class)) return ;
    //The behavior classes are automatically loaded through this function    if(substr($class,-8)=='Behavior') { // Loading behavior      if(require_cache(CORE_PATH.'Behavior/'.$class.'.')
        || require_cache(EXTEND_PATH.'Behavior/'.$class.'.')
        || require_cache(LIB_PATH.'Behavior/'.$class.'.')
        || (defined('MODE_NAME') && require_cache(MODE_PATH.ucwords(MODE_NAME).'/Behavior/'.$class.'.'))) {
        return ;
      }
    }elseif(substr($class,-5)=='Model'){ // Load the model      if((defined('GROUP_NAME') && require_cache(LIB_PATH.'Model/'.GROUP_NAME.'/'.$class.'.'))
        || require_cache(LIB_PATH.'Model/'.$class.'.')
        || require_cache(EXTEND_PATH.'Model/'.$class.'.') ) {
        return ;
      }
    }elseif(substr($class,-6)=='Action'){ // Load the controller      if((defined('GROUP_NAME') && require_cache(LIB_PATH.'Action/'.GROUP_NAME.'/'.$class.'.'))
        || require_cache(LIB_PATH.'Action/'.$class.'.')
        || require_cache(EXTEND_PATH.'Action/'.$class.'.') ) {
        return ;
      }
    }
    // Try searching according to the automatic loading path settings    $paths =  explode(',',C('APP_AUTOLOAD_PATH'));
    foreach ($paths as $path){
      if(import($path.'.'.$class))
        // If the loading class is successful, return        return ;
    }
}