From 592d05415fcc9bd77afa530313a7f883e15f084c Mon Sep 17 00:00:00 2001
From: Kristiaan Van den Eynde <kristiaan@factorial.io>
Date: Wed, 10 Apr 2019 12:13:56 +0200
Subject: [PATCH] interdiff

---
 src/Plugin/migrate/process/CallbackArray.php | 26 +++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/Plugin/migrate/process/CallbackArray.php b/src/Plugin/migrate/process/CallbackArray.php
index e4f89c2..73acc24 100644
--- a/src/Plugin/migrate/process/CallbackArray.php
+++ b/src/Plugin/migrate/process/CallbackArray.php
@@ -82,7 +82,31 @@ class CallbackArray extends Callback {
    * {@inheritdoc}
    */
   public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
-    $parameters = array_splice($this->configuration['parameters'], $this->configuration['source_index'], 0, [$value]);
+    $parameters = [];
+
+    foreach ($this->configuration['parameters'] as $parameter) {
+      $is_source = TRUE;
+
+      if ($parameter[0] == '@') {
+        $parameter = preg_replace_callback('/^(@?)((?:@@)*)([^@]|$)/', function ($matches) use (&$is_source) {
+          // If there are an odd number of @ in the beginning, it's a
+          // destination.
+          $is_source = empty($matches[1]);
+          // Remove the possible escaping and do not lose the terminating
+          // non-@ either.
+          return str_replace('@@', '@', $matches[2]) . $matches[3];
+        }, $parameter);
+      }
+
+      if ($is_source) {
+        $parameters[] = $row->getSourceProperty($parameter);
+      }
+      else {
+        $parameters[] = $row->getDestinationProperty($parameter);
+      }
+    }
+
+    array_splice($parameters, $this->configuration['source_index'], 0, [$value]);
     return call_user_func_array($this->configuration['callable'], $parameters);
   }
 
-- 
2.17.1