Write list of yaml files processed to Metadata section of output (poc)

app/Dom/Node.php

@@ -198,6 +198,50 @@ class Node implements \ArrayAccess, \Iterator
 		return $current;
 	}
 
+	/**
+	 * Set a child of this node by a dot-separate path.
+	 *
+	 * Each element of the path can either be a node name or a numeric
+	 * index representing the offset into an array
+	 *
+	 * @todo will explode if you try to write using a numeric index to an array
+	 *       element that doesn't exist
+	 * @param string $path
+	 * @param Node   $node
+	 */
+	public function addChildUnderPath(string $path, Node $node): void
+	{
+		$path = explode('.', $path);
+		$current = $this;
+
+		while (sizeof($path))
+		{
+			$next = array_shift($path);
+			if (is_numeric($next))
+			{
+				$current = $current[$next];
+			}
+			else
+			{
+				$next_node = $current->getChildByName($next);
+
+				if (!isset($next_node))
+				{
+					$next_node = new Node($current, $next);
+					$current->addChild($next_node);
+					$current = $next_node;
+				}
+			}
+
+			if (!isset($current))
+			{
+				return;
+			}
+		}
+
+		$current->addChild($node);
+	}
+
 	/**
 	 * Add a node to this node's children.
 	 *

app/Engine/Engine.php

@@ -76,11 +76,15 @@ class Engine
 					continue;
 				}
 			}
-			echo '=> '.$files[$i].PHP_EOL;
 			$this->compileDocument($document, $options);
 		}
 
-		return $this->getOutput();
+		// Set metadata in output
+		$document = $this->getOutputDocument();
+
+		$document->addChildUnderPath('Metadata', new \App\Dom\NodeValue(null, 'Stack', implode(', ', $files)));
+
+		return $this->serialize->serialize($document);
 	}
 
 	/**