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