+<?php
+/**
+ * The general feature management class. No instance is needed as this class
+ * has only public methods that are static.
+ *
+ * @author Roland Haeder <webmaster@ship-simu.org>
+ * @version 0.0.0
+ * @copyright Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2015 Core Developer Team
+ * @license GNU GPL 3.0 or any newer version
+ * @link http://www.ship-simu.org
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+class FrameworkFeature extends BaseFrameworkSystem implements Feature {
+ // Exception code constants
+ const EXCEPTION_FEATURE_METHOD_NOT_CALLABLE = 0x400;
+
+ /**
+ * "Cache" for enabled, available feature instances
+ *
+ * A typical available entry looks like this:
+ *
+ * array(
+ * 'is_enabled' => TRUE,
+ * 'is_available' => TRUE,
+ * 'instance' => SomeFeature Object
+ * )
+ *
+ * And a typical disabled entry looks like this:
+ *
+ * array(
+ * 'is_enabled' => FALSE,
+ * 'is_available' => FALSE,
+ * 'instance' => NULL
+ * )
+ */
+ private static $enabledFeatures = array();
+
+ /**
+ * Protected constructor
+ *
+ * @return void
+ */
+ protected function __construct () {
+ // Call parent constructor
+ parent::__construct(__CLASS__);
+ }
+
+ /**
+ * Checks whether the given feature is enabled in configuration. The user
+ * shall be able to disable features, even when they *could* be available.
+ *
+ * @param $featureName Name of the feature to be checked
+ * @return $isEnabled Whether the given feature is enabled
+ */
+ public static function isFeatureEnabled ($featureName) {
+ // Is the cache set?
+ if (!isset(self::$enabledFeatures[$featureName]['is_enabled'])) {
+ // Generate config key
+ $configKey = sprintf('enable_feature_%s', $featureName);
+
+ // Check configuration
+ self::$enabledFeatures[$featureName]['is_enabled'] = (FrameworkConfiguration::getSelfInstance()->getConfigEntry($configKey) === 'Y');
+ } // END - if
+
+ // Return "cached" status
+ return self::$enabledFeatures[$featureName]['is_enabled'];
+ }
+
+ /**
+ * Checks whether the given feature is enabled and available. It may be
+ * enabled by the user, but is not available due to e.g. a missing PECL
+ * extension or whatever is needed to have this feature available. If you
+ * don't write a pre filters for checking PHP requirements, this is the
+ * method you want to use.
+ *
+ * @param $featureName Name of the feature to be checked on availability
+ * @return $isAvailable Whether the given feature is available
+ */
+ public static function isFeatureAvailable ($featureName) {
+ // Is the cache set?
+ if (!isset(self::$enabledFeatures[$featureName]['is_available'])) {
+ // Default is not available
+ self::$enabledFeatures[$featureName]['is_available'] = FALSE;
+ self::$enabledFeatures[$featureName]['instance'] = NULL;
+
+ // Is the feature enabled?
+ if (!self::isFeatureEnabled($featureName)) {
+ // Then it can't be available
+ return FALSE;
+ } // END - if
+
+ // Create config key (for feature class lookup)
+ $configKey = sprintf('feature_%s_class', $featureName);
+
+ // Now try to get the instance
+ try {
+ // Try to get an instance
+ self::$enabledFeatures[$featureName]['instance'] = ObjectFactory::createObjectByConfiguredName($configKey);
+
+ // Now let the feature test itself's availability
+ self::$enabledFeatures[$featureName]['is_available'] = self::$enabledFeatures[$featureName]['instance']->isFeatureAvailable();
+ } catch (NoClassException $e) {
+ // Feature class not found
+ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d]: Feature %s not available due to missing feature class. Disabling feature ...', __METHOD__, __LINE__, $featureName));
+ }
+ } // END - if
+
+ // Return "cached" status
+ return self::$enabledFeatures[$featureName]['is_available'];
+ }
+
+ /**
+ * Calls the feature's method and handles some arguments (if not given,
+ * NULL) to it. Any returned value is being forwarded to the caller, even
+ * when the doc-tag says 'void' as returned value.
+ *
+ * @param $featureName Name of the feature, it must be available at this point
+ * @param $featureMethod Method name of the feature's class
+ * @param $args Any arguments that should be handled over
+ * @return $return Anything the feature's method has returned
+ * @throws FeatureMethodNotCallableException If the requested method cannot be called
+ */
+ public static function callFeature ($featureName, $featureMethod, array $args = NULL) {
+ /*
+ * Please make sure that isFeatureAvailable() has been called and it has
+ * returned TRUE before calling this method.
+ */
+ assert(self::isFeatureAvailable($featureName));
+
+ // Array for call-back
+ $callable = array(self::$enabledFeatures[$featureName]['instance'], $featureMethod);
+
+ // So is the feature's method callable?
+ if (!is_callable($callable)) {
+ // Not callable method requested
+ throw new FeatureMethodNotCallableException(array(self::$enabledFeatures[$featureName]['instance'], $featureMethod), self::EXCEPTION_FEATURE_METHOD_NOT_CALLABLE);
+ } // END - if
+
+ // Then call it
+ $return = call_user_func_array($callable, $args);
+
+ // Return any returned value
+ return $return;
+ }
+}
+
+// [EOF]
+?>
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