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lib/pkp/classes/mail/variables/Variable.php

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+<?php
+
+/**
+ * @file classes/mail/variables/Variable.php
+ *
+ * Copyright (c) 2014-2021 Simon Fraser University
+ * Copyright (c) 2000-2021 John Willinsky
+ * Distributed under the GNU GPL v3. For full terms see the file docs/COPYING.
+ *
+ * @class Variable
+ *
+ * @ingroup mail_variables
+ *
+ * @brief A base class for email template variables
+ */
+
+namespace PKP\mail\variables;
+
+use Exception;
+use Illuminate\Support\Arr;
+use PKP\context\Context;
+use PKP\mail\Mailable;
+
+abstract class Variable
+{
+    protected Mailable $mailable;
+
+    public function __construct(Mailable $mailable)
+    {
+        $this->mailable = $mailable;
+    }
+
+    /**
+     * Retrieve mailable context from associated variables, see pkp/pkp-lib#8204
+     */
+    protected function getContext(): Context
+    {
+        $contextEmailVariable = Arr::first($this->mailable->getVariables(), function (Variable $variable) {
+            return $variable instanceof ContextEmailVariable;
+        });
+
+        if (!$contextEmailVariable) {
+            throw new Exception(static::class . ' is unable to generate email variables without providing the context to the Mailable');
+        }
+
+        return $contextEmailVariable->getContextFromVariable();
+    }
+
+    /**
+     * Get descriptions of the variables provided by this class
+     *
+     * @return string[]
+     */
+    abstract public static function descriptions(): array;
+
+    /**
+     * Get the value of variables supported by this class
+     *
+     * @return string[]
+     */
+    abstract public function values(string $locale): array;
+}