1: <?php
  2: /**
  3:  * CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
  4:  * Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
  5:  *
  6:  * Licensed under The MIT License
  7:  * For full copyright and license information, please see the LICENSE.txt
  8:  * Redistributions of files must retain the above copyright notice.
  9:  *
 10:  * @copyright     Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 11:  * @link          https://cakephp.org CakePHP(tm) Project
 12:  * @since         2.0.0
 13:  * @license       https://opensource.org/licenses/mit-license.php MIT License
 14:  */
 15: namespace Cake\View;
 16: 
 17: use Cake\Core\App;
 18: use Cake\Core\ObjectRegistry;
 19: use Cake\Event\EventDispatcherInterface;
 20: use Cake\Event\EventDispatcherTrait;
 21: use Cake\View\Exception\MissingHelperException;
 22: 
 23: /**
 24:  * HelperRegistry is used as a registry for loaded helpers and handles loading
 25:  * and constructing helper class objects.
 26:  */
 27: class HelperRegistry extends ObjectRegistry implements EventDispatcherInterface
 28: {
 29:     use EventDispatcherTrait;
 30: 
 31:     /**
 32:      * View object to use when making helpers.
 33:      *
 34:      * @var \Cake\View\View
 35:      */
 36:     protected $_View;
 37: 
 38:     /**
 39:      * Constructor
 40:      *
 41:      * @param \Cake\View\View $view View object.
 42:      */
 43:     public function __construct(View $view)
 44:     {
 45:         $this->_View = $view;
 46:         $this->setEventManager($view->getEventManager());
 47:     }
 48: 
 49:     /**
 50:      * Tries to lazy load a helper based on its name, if it cannot be found
 51:      * in the application folder, then it tries looking under the current plugin
 52:      * if any
 53:      *
 54:      * @param string $helper The helper name to be loaded
 55:      * @return bool whether the helper could be loaded or not
 56:      * @throws \Cake\View\Exception\MissingHelperException When a helper could not be found.
 57:      *    App helpers are searched, and then plugin helpers.
 58:      */
 59:     public function __isset($helper)
 60:     {
 61:         if (isset($this->_loaded[$helper])) {
 62:             return true;
 63:         }
 64: 
 65:         try {
 66:             $this->load($helper);
 67:         } catch (Exception\MissingHelperException $exception) {
 68:             if ($this->_View->getPlugin()) {
 69:                 $this->load($this->_View->getPlugin() . '.' . $helper);
 70: 
 71:                 return true;
 72:             }
 73:         }
 74: 
 75:         if (!empty($exception)) {
 76:             throw $exception;
 77:         }
 78: 
 79:         return true;
 80:     }
 81: 
 82:     /**
 83:      * Provide public read access to the loaded objects
 84:      *
 85:      * @param string $name Name of property to read
 86:      * @return mixed
 87:      */
 88:     public function __get($name)
 89:     {
 90:         if (isset($this->_loaded[$name])) {
 91:             return $this->_loaded[$name];
 92:         }
 93:         if (isset($this->{$name})) {
 94:             return $this->_loaded[$name];
 95:         }
 96: 
 97:         return null;
 98:     }
 99: 
100:     /**
101:      * Resolve a helper classname.
102:      *
103:      * Part of the template method for Cake\Core\ObjectRegistry::load()
104:      *
105:      * @param string $class Partial classname to resolve.
106:      * @return string|false Either the correct classname or false.
107:      */
108:     protected function _resolveClassName($class)
109:     {
110:         return App::className($class, 'View/Helper', 'Helper');
111:     }
112: 
113:     /**
114:      * Throws an exception when a helper is missing.
115:      *
116:      * Part of the template method for Cake\Core\ObjectRegistry::load()
117:      * and Cake\Core\ObjectRegistry::unload()
118:      *
119:      * @param string $class The classname that is missing.
120:      * @param string $plugin The plugin the helper is missing in.
121:      * @return void
122:      * @throws \Cake\View\Exception\MissingHelperException
123:      */
124:     protected function _throwMissingClassError($class, $plugin)
125:     {
126:         throw new MissingHelperException([
127:             'class' => $class . 'Helper',
128:             'plugin' => $plugin
129:         ]);
130:     }
131: 
132:     /**
133:      * Create the helper instance.
134:      *
135:      * Part of the template method for Cake\Core\ObjectRegistry::load()
136:      * Enabled helpers will be registered with the event manager.
137:      *
138:      * @param string $class The class to create.
139:      * @param string $alias The alias of the loaded helper.
140:      * @param array $settings An array of settings to use for the helper.
141:      * @return \Cake\View\Helper The constructed helper class.
142:      */
143:     protected function _create($class, $alias, $settings)
144:     {
145:         $instance = new $class($this->_View, $settings);
146: 
147:         $enable = isset($settings['enabled']) ? $settings['enabled'] : true;
148:         if ($enable) {
149:             $this->getEventManager()->on($instance);
150:         }
151: 
152:         return $instance;
153:     }
154: }
155: