add exportElementProvider to provide elements dynamically to export manager

Export/ExportElementsProviderInterface.php

@@ -0,0 +1,35 @@
+<?php
+/*
+ * Copyright (C) 2018 Champs Libres Cooperative <info@champs-libres.coop>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+namespace Chill\MainBundle\Export;
+
+/**
+ * Interface to provide export elements dynamically.
+ * 
+ * The typical use case is providing exports or aggregators depending on 
+ * dynamic data. Example: providing exports for reports, reports depending
+ * on data stored in database.
+ *
+ * @author Julien Fastré <julien.fastre@champs-libres.coop>
+ */
+interface ExportElementsProviderInterface
+{
+    /**
+     * @return ExportElementInterface[]
+     */
+    public function getExportElements();
+}

Export/ExportManager.php

@@ -169,6 +169,26 @@ class ExportManager
         $this->formatters[$alias] = $formatter;
     }
     
+    public function addExportElementsProvider(ExportElementsProviderInterface $provider, $prefix)
+    {
+        foreach ($provider->getExportElements() as $suffix => $element) {
+            $alias = $prefix.'_'.$suffix;
+            
+            if ($element instanceof ExportInterface) {
+                $this->addExport($element, $alias);
+            } elseif ($element instanceof FilterInterface) {
+                $this->addFilter($element, $alias);
+            } elseif ($element instanceof AggregatorInterface) {
+                $this->addAggregator($element, $alias);
+            } elseif ($element instanceof FormatterInterface) {
+                $this->addFormatter($element, $alias);
+            } else {
+                throw new \LogicException("This element ".\get_class($element)." "
+                    . "is not an instance of export element");
+            }
+        }
+    }
+    
     /**
      * 
      * @return string[] the existing type for known exports