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typo3conf/ext/vhs/Classes/ViewHelpers/Extension/LoadedViewHelper.php

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+<?php
+namespace FluidTYPO3\Vhs\ViewHelpers\Extension;
+
+/*
+ * This file is part of the FluidTYPO3/Vhs project under GPLv2 or later.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.md file that was distributed with this source code.
+ */
+
+use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Fluid\Core\ViewHelper\AbstractConditionViewHelper;
+use FluidTYPO3\Vhs\Traits\ConditionViewHelperTrait;
+
+/**
+ * ### Extension: Loaded (Condition) ViewHelper
+ *
+ * Condition to check if an extension is loaded.
+ *
+ * ### Example:
+ *
+ *     {v:extension.loaded(extensionName: 'news', then: 'yes', else: 'no')}
+ *
+ *     <v:extension.loaded extensionName="news">
+ *         ...
+ *     </v:extension.loaded>
+ *
+ * @author Claus Due <claus@namelesscoder.net>
+ * @package Vhs
+ * @subpackage ViewHelpers\Extension
+ */
+class LoadedViewHelper extends AbstractConditionViewHelper {
+
+	use ConditionViewHelperTrait;
+
+	/**
+	 * Initialize arguments
+	 */
+	public function initializeArguments() {
+		parent::initializeArguments();
+		$this->registerArgument('extensionName', 'string', 'Name of extension that must be loaded in order to evaluate as TRUE, UpperCamelCase', TRUE);
+	}
+
+	/**
+	 * This method decides if the condition is TRUE or FALSE. It can be overriden in extending viewhelpers to adjust functionality.
+	 *
+	 * @param array $arguments ViewHelper arguments to evaluate the condition for this ViewHelper, allows for flexiblity in overriding this method.
+	 * @return bool
+	 */
+	static protected function evaluateCondition($arguments = NULL) {
+		$extensionName = $arguments['extensionName'];
+		$extensionKey = GeneralUtility::camelCaseToLowerCaseUnderscored($extensionName);
+		$isLoaded = ExtensionManagementUtility::isLoaded($extensionKey);
+		return TRUE === $isLoaded;
+	}
+
+}