new export options

app/Tables/BaseExporter.php

@@ -37,6 +37,30 @@ abstract class BaseExporter
         $this->columns = Column::columnsFromJson($table->revision->columns);
     }
 
+    protected function getHeaderComment($prefix = " ")
+    {
+        $table = $this->table;
+        $owner = $this->table->owner;
+
+        $s =
+            $prefix."Table \"$table->title\" by $owner->title\n".
+            $prefix."exported ".date('M n, Y \\a\\t G:i')."\n".
+            $prefix."\n".
+            $prefix."License: ". str_replace("\n", "\n$prefix", $table->license ?: 'CC0') ."\n".
+            $prefix."\n".
+            $prefix."Upstream: https://datatable.directory/$owner->handle/$table->name\n";
+
+        $s .=
+            $prefix."\n".
+            $prefix."Columns:\n";
+
+        foreach ($this->columns as $c) {
+            $s .= $prefix." - $c->name ... $c->title\n";
+        }
+
+        return $s;
+    }
+
     /**
      * @return string - mime type for the downloaded file
      */