inc/classes/main/feature/class_FrameworkFeature.php

   1 <?php
   2 /**
   3  * The general feature management class. No instance is needed as this class
   4  * has only public methods that are static.
   5  *
   6  * @author              Roland Haeder <webmaster@ship-simu.org>
   7  * @version             0.0.0
   8  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2015 Core Developer Team
   9  * @license             GNU GPL 3.0 or any newer version
  10  * @link                http://www.ship-simu.org
  11  *
  12  * This program is free software: you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation, either version 3 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  24  */
  25 class FrameworkFeature extends BaseFrameworkSystem {
  26         // Exception code constants
  27         const EXCEPTION_FEATURE_METHOD_NOT_CALLABLE = 0x400;
  28
  29         /**
  30          * "Cache" for enabled, available feature instances
  31          *
  32          * A typical available entry looks like this:
  33          *
  34          * array(
  35          *     'is_enabled'   => TRUE,
  36          *     'is_available' => TRUE,
  37          *     'instance'     => SomeFeature Object
  38          * )
  39          *
  40          * And a typical disabled entry looks like this:
  41          *
  42          * array(
  43          *     'is_enabled'   => FALSE,
  44          *     'is_available' => FALSE,
  45          *     'instance'     => NULL
  46          * )
  47          */
  48         private static $enabledFeatures = array();
  49
  50         /**
  51          * Protected constructor
  52          *
  53          * @return      void
  54          */
  55         protected function __construct () {
  56                 // Call parent constructor
  57                 parent::__construct(__CLASS__);
  58         }
  59
  60         /**
  61          * Checks whether the given feature is enabled in configuration. The user
  62          * shall be able to disable features, even when they *could* be available.
  63          *
  64          * @param       $featureName    Name of the feature to be checked
  65          * @return      $isEnabled              Whether the given feature is enabled
  66          */
  67         public static function isFeatureEnabled ($featureName) {
  68                 // Is the cache set?
  69                 if (!isset(self::$enabledFeatures[$featureName]['is_enabled'])) {
  70                         // Generate config key
  71                         $configKey = sprintf('enable_feature_%s', $featureName);
  72
  73                         // Check configuration
  74                         self::$enabledFeatures[$featureName]['is_enabled'] = (FrameworkConfiguration::getSelfInstance()->getConfigEntry($configKey) === 'Y');
  75                 } // END - if
  76
  77                 // Return "cached" status
  78                 return self::$enabledFeatures[$featureName]['is_enabled'];
  79         }
  80
  81         /**
  82          * Checks whether the given feature is enabled and available. It may be
  83          * enabled by the user, but is not available due to e.g. a missing PECL
  84          * extension or whatever is needed to have this feature available. If you
  85          * don't write a pre filters for checking PHP requirements, this is the
  86          * method you want to use.
  87          *
  88          * @param       $featureName    Name of the feature to be checked on availability
  89          * @return      $isAvailable    Whether the given feature is available
  90          */
  91         public static function isFeatureAvailable ($featureName) {
  92                 // Debug message
  93                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: featureName=%s - CALLED!', __METHOD__, __LINE__, $featureName));
  94
  95                 // Is the cache set?
  96                 if (!isset(self::$enabledFeatures[$featureName]['is_available'])) {
  97                         // Default is not available
  98                         self::$enabledFeatures[$featureName]['is_available'] = FALSE;
  99                         self::$enabledFeatures[$featureName]['instance']     = NULL;
 100
 101                         // Is the feature enabled?
 102                         if (!self::isFeatureEnabled($featureName)) {
 103                                 // Then it can't be available
 104                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: Feature "%s"is not enabled.', __METHOD__, __LINE__, $featureName));
 105                                 return FALSE;
 106                         } // END - if
 107
 108                         // Create config key (for feature class lookup)
 109                         $configKey = sprintf('feature_%s_class', $featureName);
 110
 111                         // Debug message
 112                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: configKey=%s', __METHOD__, __LINE__, $configKey));
 113
 114                         // Now try to get the instance
 115                         try {
 116                                 // Try to get an instance
 117                                 self::$enabledFeatures[$featureName]['instance'] = ObjectFactory::createObjectByConfiguredName($configKey);
 118
 119                                 // Now let the feature test itself's availability
 120                                 self::$enabledFeatures[$featureName]['is_available'] = self::$enabledFeatures[$featureName]['instance']->isFeatureAvailable();
 121                         } catch (NoClassException $e) {
 122                                 // Feature class not found
 123                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: Feature "%s"is not available due to missing feature class. Disabling feature ...', __METHOD__, __LINE__, $featureName));
 124                         }
 125                 } // END - if
 126
 127                 // Debug message
 128                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: featureName=%s,isAvailable=%d - EXIT!', __METHOD__, __LINE__, $featureName, intval(self::$enabledFeatures[$featureName]['is_available'])));
 129
 130                 // Return "cached" status
 131                 return self::$enabledFeatures[$featureName]['is_available'];
 132         }
 133
 134         /**
 135          * Calls the feature's method and handles some arguments (if not given,
 136          * NULL) to it. Any returned value is being forwarded to the caller, even
 137          * when the doc-tag says 'void' as returned value.
 138          *
 139          * @param       $featureName    Name of the feature, it must be available at this point
 140          * @param       $featureMethod  Method name of the feature's class
 141          * @param       $args                   Any arguments that should be handled over
 142          * @return      $return                 Anything the feature's method has returned
 143          * @throws      FeatureMethodNotCallableException       If the requested method cannot be called
 144          */
 145         public static function callFeature ($featureName, $featureMethod, array $args = NULL) {
 146                 /*
 147                  * Please make sure that isFeatureAvailable() has been called and it has
 148                  * returned TRUE before calling this method.
 149                  */
 150                 assert(self::isFeatureAvailable($featureName));
 151
 152                 // Array for call-back
 153                 $callable = array(self::$enabledFeatures[$featureName]['instance'], 'featureMethod' . self::convertToClassName($featureMethod));
 154
 155                 // So is the feature's method callable?
 156                 if (!is_callable($callable)) {
 157                         // Not callable method requested
 158                         throw new FeatureMethodNotCallableException(array(self::$enabledFeatures[$featureName]['instance'], $featureMethod), self::EXCEPTION_FEATURE_METHOD_NOT_CALLABLE);
 159                 } // END - if
 160
 161                 // Then call it
 162                 $return = call_user_func_array($callable, $args);
 163
 164                 // Return any returned value
 165                 return $return;
 166         }
 167 }
 168
 169 // [EOF]
 170 ?>