framework/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\Loader\NoClassException;
   9 use CoreFramework\Object\BaseFrameworkSystem;
  10
  11 /**
  12  * The general feature management class. No instance is needed as this class
  13  * has only public methods that are static.
  14  *
  15  * @author              Roland Haeder <webmaster@ship-simu.org>
  16  * @version             0.0.0
  17  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2017 Core Developer Team
  18  * @license             GNU GPL 3.0 or any newer version
  19  * @link                http://www.ship-simu.org
  20  *
  21  * This program is free software: you can redistribute it and/or modify
  22  * it under the terms of the GNU General Public License as published by
  23  * the Free Software Foundation, either version 3 of the License, or
  24  * (at your option) any later version.
  25  *
  26  * This program is distributed in the hope that it will be useful,
  27  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  29  * GNU General Public License for more details.
  30  *
  31  * You should have received a copy of the GNU General Public License
  32  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  33  */
  34 class FrameworkFeature extends BaseFrameworkSystem {
  35         // Exception code constants
  36         const EXCEPTION_FEATURE_METHOD_NOT_CALLABLE = 0x400;
  37
  38         /**
  39          * "Cache" for enabled, available feature instances
  40          *
  41          * A typical available entry looks like this:
  42          *
  43          * array(
  44          *     'is_enabled'   => TRUE,
  45          *     'is_available' => TRUE,
  46          *     'instance'     => SomeFeature Object
  47          * )
  48          *
  49          * And a typical disabled entry looks like this:
  50          *
  51          * array(
  52          *     'is_enabled'   => FALSE,
  53          *     'is_available' => FALSE,
  54          *     'instance'     => NULL
  55          * )
  56          */
  57         private static $enabledFeatures = array();
  58
  59         /**
  60          * Protected constructor
  61          *
  62          * @return      void
  63          */
  64         protected function __construct () {
  65                 // Call parent constructor
  66                 parent::__construct(__CLASS__);
  67         }
  68
  69         /**
  70          * Checks whether the given feature is enabled in configuration. The user
  71          * shall be able to disable features, even when they *could* be available.
  72          *
  73          * @param       $featureName    Name of the feature to be checked
  74          * @return      $isEnabled              Whether the given feature is enabled
  75          */
  76         public static function isFeatureEnabled ($featureName) {
  77                 // Is the cache set?
  78                 if (!isset(self::$enabledFeatures[$featureName]['is_enabled'])) {
  79                         // Generate config key
  80                         $configKey = sprintf('enable_feature_%s', $featureName);
  81
  82                         // Check configuration
  83                         self::$enabledFeatures[$featureName]['is_enabled'] = (FrameworkConfiguration::getSelfInstance()->getConfigEntry($configKey) === 'Y');
  84                 } // END - if
  85
  86                 // Return "cached" status
  87                 return self::$enabledFeatures[$featureName]['is_enabled'];
  88         }
  89
  90         /**
  91          * Checks whether the given feature is enabled and available. It may be
  92          * enabled by the user, but is not available due to e.g. a missing PECL
  93          * extension or whatever is needed to have this feature available. If you
  94          * don't write a pre filters for checking PHP requirements, this is the
  95          * method you want to use.
  96          *
  97          * @param       $featureName    Name of the feature to be checked on availability
  98          * @return      $isAvailable    Whether the given feature is available
  99          */
 100         public static function isFeatureAvailable ($featureName) {
 101                 // Debug message
 102                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d]: featureName=%s - CALLED!', __METHOD__, __LINE__, $featureName));
 103
 104                 // Is the cache set?
 105                 if (!isset(self::$enabledFeatures[$featureName]['is_available'])) {
 106                         // Default is not available
 107                         self::$enabledFeatures[$featureName]['is_available'] = FALSE;
 108                         self::$enabledFeatures[$featureName]['instance']     = NULL;
 109
 110                         // Is the feature enabled?
 111                         if (!self::isFeatureEnabled($featureName)) {
 112                                 // Then it can't be available
 113                                 self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d]: Feature "%s"is not enabled.', __METHOD__, __LINE__, $featureName));
 114                                 return FALSE;
 115                         } // END - if
 116
 117                         // Create config key (for feature class lookup)
 118                         $configKey = sprintf('feature_%s_class', $featureName);
 119
 120                         // Debug message
 121                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d]: configKey=%s', __METHOD__, __LINE__, $configKey));
 122
 123                         // Now try to get the instance
 124                         try {
 125                                 // Try to get an instance
 126                                 self::$enabledFeatures[$featureName]['instance'] = ObjectFactory::createObjectByConfiguredName($configKey);
 127
 128                                 // Now let the feature test itself's availability
 129                                 self::$enabledFeatures[$featureName]['is_available'] = self::$enabledFeatures[$featureName]['instance']->isFeatureAvailable();
 130                         } catch (NoClassException $e) {
 131                                 // Feature class not found
 132                                 self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d]: Feature "%s"is not available due to missing feature class. Disabling feature ...', __METHOD__, __LINE__, $featureName));
 133                         }
 134                 } // END - if
 135
 136                 // Debug message
 137                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d]: featureName=%s,isAvailable=%d - EXIT!', __METHOD__, __LINE__, $featureName, intval(self::$enabledFeatures[$featureName]['is_available'])));
 138
 139                 // Return "cached" status
 140                 return self::$enabledFeatures[$featureName]['is_available'];
 141         }
 142
 143         /**
 144          * Calls the feature's method and handles some arguments (if not given,
 145          * NULL) to it. Any returned value is being forwarded to the caller, even
 146          * when the doc-tag says 'void' as returned value.
 147          *
 148          * @param       $featureName    Name of the feature, it must be available at this point
 149          * @param       $featureMethod  Method name of the feature's class
 150          * @param       $args                   Any arguments that should be handled over
 151          * @return      $return                 Anything the feature's method has returned
 152          * @throws      FeatureMethodNotCallableException       If the requested method cannot be called
 153          */
 154         public static function callFeature ($featureName, $featureMethod, array $args = NULL) {
 155                 /*
 156                  * Please make sure that isFeatureAvailable() has been called and it has
 157                  * returned TRUE before calling this method.
 158                  */
 159                 assert(self::isFeatureAvailable($featureName));
 160
 161                 // Array for call-back
 162                 $callable = array(self::$enabledFeatures[$featureName]['instance'], 'featureMethod' . self::convertToClassName($featureMethod));
 163
 164                 // So is the feature's method callable?
 165                 if (!is_callable($callable)) {
 166                         // Not callable method requested
 167                         throw new FeatureMethodNotCallableException(array(self::$enabledFeatures[$featureName]['instance'], $featureMethod), self::EXCEPTION_FEATURE_METHOD_NOT_CALLABLE);
 168                 } // END - if
 169
 170                 // Then call it
 171                 $return = call_user_func_array($callable, $args);
 172
 173                 // Return any returned value
 174                 return $return;
 175         }
 176
 177 }