inc/main/classes/feature/class_FrameworkFeature.php

   1 <?php
   2 // Own namespace
   3 namespace CoreFramework\Feature;
   4
   5 // Import framework stuff
   6 use CoreFramework\Configuration\FrameworkConfiguration;
   7 use CoreFramework\Factory\ObjectFactory;
   8 use CoreFramework\Object\BaseFrameworkSystem;
   9
  10 /**
  11  * The general feature management class. No instance is needed as this class
  12  * has only public methods that are static.
  13  *
  14  * @author              Roland Haeder <webmaster@ship-simu.org>
  15  * @version             0.0.0
  16  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2017 Core Developer Team
  17  * @license             GNU GPL 3.0 or any newer version
  18  * @link                http://www.ship-simu.org
  19  *
  20  * This program is free software: you can redistribute it and/or modify
  21  * it under the terms of the GNU General Public License as published by
  22  * the Free Software Foundation, either version 3 of the License, or
  23  * (at your option) any later version.
  24  *
  25  * This program is distributed in the hope that it will be useful,
  26  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  27  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  28  * GNU General Public License for more details.
  29  *
  30  * You should have received a copy of the GNU General Public License
  31  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  32  */
  33 class FrameworkFeature extends BaseFrameworkSystem {
  34         // Exception code constants
  35         const EXCEPTION_FEATURE_METHOD_NOT_CALLABLE = 0x400;
  36
  37         /**
  38          * "Cache" for enabled, available feature instances
  39          *
  40          * A typical available entry looks like this:
  41          *
  42          * array(
  43          *     'is_enabled'   => TRUE,
  44          *     'is_available' => TRUE,
  45          *     'instance'     => SomeFeature Object
  46          * )
  47          *
  48          * And a typical disabled entry looks like this:
  49          *
  50          * array(
  51          *     'is_enabled'   => FALSE,
  52          *     'is_available' => FALSE,
  53          *     'instance'     => NULL
  54          * )
  55          */
  56         private static $enabledFeatures = array();
  57
  58         /**
  59          * Protected constructor
  60          *
  61          * @return      void
  62          */
  63         protected function __construct () {
  64                 // Call parent constructor
  65                 parent::__construct(__CLASS__);
  66         }
  67
  68         /**
  69          * Checks whether the given feature is enabled in configuration. The user
  70          * shall be able to disable features, even when they *could* be available.
  71          *
  72          * @param       $featureName    Name of the feature to be checked
  73          * @return      $isEnabled              Whether the given feature is enabled
  74          */
  75         public static function isFeatureEnabled ($featureName) {
  76                 // Is the cache set?
  77                 if (!isset(self::$enabledFeatures[$featureName]['is_enabled'])) {
  78                         // Generate config key
  79                         $configKey = sprintf('enable_feature_%s', $featureName);
  80
  81                         // Check configuration
  82                         self::$enabledFeatures[$featureName]['is_enabled'] = (FrameworkConfiguration::getSelfInstance()->getConfigEntry($configKey) === 'Y');
  83                 } // END - if
  84
  85                 // Return "cached" status
  86                 return self::$enabledFeatures[$featureName]['is_enabled'];
  87         }
  88
  89         /**
  90          * Checks whether the given feature is enabled and available. It may be
  91          * enabled by the user, but is not available due to e.g. a missing PECL
  92          * extension or whatever is needed to have this feature available. If you
  93          * don't write a pre filters for checking PHP requirements, this is the
  94          * method you want to use.
  95          *
  96          * @param       $featureName    Name of the feature to be checked on availability
  97          * @return      $isAvailable    Whether the given feature is available
  98          */
  99         public static function isFeatureAvailable ($featureName) {
 100                 // Debug message
 101                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: featureName=%s - CALLED!', __METHOD__, __LINE__, $featureName));
 102
 103                 // Is the cache set?
 104                 if (!isset(self::$enabledFeatures[$featureName]['is_available'])) {
 105                         // Default is not available
 106                         self::$enabledFeatures[$featureName]['is_available'] = FALSE;
 107                         self::$enabledFeatures[$featureName]['instance']     = NULL;
 108
 109                         // Is the feature enabled?
 110                         if (!self::isFeatureEnabled($featureName)) {
 111                                 // Then it can't be available
 112                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: Feature "%s"is not enabled.', __METHOD__, __LINE__, $featureName));
 113                                 return FALSE;
 114                         } // END - if
 115
 116                         // Create config key (for feature class lookup)
 117                         $configKey = sprintf('feature_%s_class', $featureName);
 118
 119                         // Debug message
 120                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: configKey=%s', __METHOD__, __LINE__, $configKey));
 121
 122                         // Now try to get the instance
 123                         try {
 124                                 // Try to get an instance
 125                                 self::$enabledFeatures[$featureName]['instance'] = ObjectFactory::createObjectByConfiguredName($configKey);
 126
 127                                 // Now let the feature test itself's availability
 128                                 self::$enabledFeatures[$featureName]['is_available'] = self::$enabledFeatures[$featureName]['instance']->isFeatureAvailable();
 129                         } catch (NoClassException $e) {
 130                                 // Feature class not found
 131                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: Feature "%s"is not available due to missing feature class. Disabling feature ...', __METHOD__, __LINE__, $featureName));
 132                         }
 133                 } // END - if
 134
 135                 // Debug message
 136                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: featureName=%s,isAvailable=%d - EXIT!', __METHOD__, __LINE__, $featureName, intval(self::$enabledFeatures[$featureName]['is_available'])));
 137
 138                 // Return "cached" status
 139                 return self::$enabledFeatures[$featureName]['is_available'];
 140         }
 141
 142         /**
 143          * Calls the feature's method and handles some arguments (if not given,
 144          * NULL) to it. Any returned value is being forwarded to the caller, even
 145          * when the doc-tag says 'void' as returned value.
 146          *
 147          * @param       $featureName    Name of the feature, it must be available at this point
 148          * @param       $featureMethod  Method name of the feature's class
 149          * @param       $args                   Any arguments that should be handled over
 150          * @return      $return                 Anything the feature's method has returned
 151          * @throws      FeatureMethodNotCallableException       If the requested method cannot be called
 152          */
 153         public static function callFeature ($featureName, $featureMethod, array $args = NULL) {
 154                 /*
 155                  * Please make sure that isFeatureAvailable() has been called and it has
 156                  * returned TRUE before calling this method.
 157                  */
 158                 assert(self::isFeatureAvailable($featureName));
 159
 160                 // Array for call-back
 161                 $callable = array(self::$enabledFeatures[$featureName]['instance'], 'featureMethod' . self::convertToClassName($featureMethod));
 162
 163                 // So is the feature's method callable?
 164                 if (!is_callable($callable)) {
 165                         // Not callable method requested
 166                         throw new FeatureMethodNotCallableException(array(self::$enabledFeatures[$featureName]['instance'], $featureMethod), self::EXCEPTION_FEATURE_METHOD_NOT_CALLABLE);
 167                 } // END - if
 168
 169                 // Then call it
 170                 $return = call_user_func_array($callable, $args);
 171
 172                 // Return any returned value
 173                 return $return;
 174         }
 175
 176 }