YAML now supports a mostly no-op round trip to/from DOM

Changes some formatting as far as inline objects/arrays and loses comments, but should be all we need for what we're doing

app/Dom/Node.php

@@ -40,11 +40,21 @@ class Node implements \ArrayAccess, \Iterator
 		return $this->name;
 	}
 
+	public function hasName(): bool
+	{
+		return isset($this->name);
+	}
+
 	public function getParent(): Node
 	{
 		return $this->parent;
 	}
 
+	public function hasChildren(): bool
+	{
+		return sizeof($this->children) > 0;
+	}
+
 	public function getChildren(): array
 	{
 		return $this->children;

app/Serialize/Yaml.php

@@ -24,10 +24,54 @@ class Yaml implements ISerialize, IUnserialize
 
 	public function serialize(Document $document): string
 	{
-		// TODO: Convert document to array
-		// Convert custom tags to Symfony\Component\Yaml\Tag\TaggedValue
-		// 	new TaggedValue('my_tag', ['data'=>'here'])
-		return SymfonyYaml::dump($data);
+		$data = $this->domToArray($document);
+		return SymfonyYaml::dump($data, 6);
+	}
+
+	/**
+	 * Take a DOM node and return it turned into an array appropriate
+	 * for serializing with the Symfony Yaml component.
+	 *
+	 * @param  Node  $node dom node to convert to array
+	 * @return mixed
+	 */
+	protected function domToArray(Node $node)
+	{
+		$result = null;
+		foreach ($node as $child)
+		{
+			$child_ser = $this->serializeNode($child);
+			if (is_array($child_ser))
+			{
+				if (isset($result) && !is_array($result))
+				{
+					throw new \Exception('Invalid DOM: tagged value adjacent to property map');
+				}
+				$result = $result ?? [];
+				$result = array_merge($result, $child_ser);
+			}
+			else
+			{
+				$result = $child_ser;
+			}
+		}
+		return $result;
+	}
+
+	private function serializeNode(Node $node)
+	{
+		switch (true)
+		{
+			case $node instanceof NodeFunctionValue:
+				return new TaggedValue($node->getName(), $node->getValue());
+			case $node instanceof NodeFunction:
+				return new TaggedValue($node->getName(), $this->domToArray($node));
+			case $node instanceof NodeValue:
+				return $node->hasName() ? [$node->getName() => $node->getValue()] : [$node->getValue()];
+			default:
+				return $node->hasName() ? [$node->getName() => $this->domToArray($node)] : [$this->domToArray($node)];
+		}
+		throw new \Exception('Unrecognized node type: '.get_class($node));
 	}
 
 	protected function arrayToDom(Node $parent, array $data)