diff --git a/app/Cfnpp/Compiler.php b/app/Cfnpp/Compiler.php
index 2986f66..2c302f1 100644
--- a/app/Cfnpp/Compiler.php
+++ b/app/Cfnpp/Compiler.php
@@ -41,6 +41,13 @@ class Compiler implements \App\Engine\ICompile
 	 */
 	protected $merge_functions;
 
+	/**
+	 * Stores current state of the document so it can be mutated mid-pass.
+	 *
+	 * @var Document
+	 */
+	protected $document;
+
 	/**
 	 * Register a function that can be called by the document.
 	 *
@@ -66,6 +73,19 @@ class Compiler implements \App\Engine\ICompile
 		$this->merge_functions[$name] = $callback;
 	}
 
+	public function addCondition(string $name, Node $node): void
+	{
+		$conditions = $this->document->getChildByName('Conditions');
+		if (!isset($conditions))
+		{
+			$conditions = new Node($this->document, 'Conditions');
+			$this->document->addChild($conditions);
+		}
+
+		$node->setName($name);
+		$conditions->addChild($node);
+	}
+
 	/**
 	 * Compile a set of documents and return the result.
 	 *
@@ -81,7 +101,7 @@ class Compiler implements \App\Engine\ICompile
 		}
 
 		// Initialize state
-		$document = null;
+		$this->document = null;
 		$this->functions = [];
 		$this->merge_functions = [];
 
@@ -89,11 +109,11 @@ class Compiler implements \App\Engine\ICompile
 		$cfnpp_functions = new Functions($this, $options);
 		$cfnpp_functions->register($this);
 
-		$document = $this->pass_0($documents, $options);
-		$this->pass_1($document, $options);
-		$this->pass_2($document, $options);
+		$this->document = $this->pass_0($documents, $options);
+		$this->pass_1($this->document, $options);
+		$this->pass_2($this->document, $options);
 
-		return $document;
+		return $this->document;
 
 		// Process each passed document
 		/*
@@ -207,7 +227,7 @@ class Compiler implements \App\Engine\ICompile
 			{
 				if (isset($nodes[$variable_node->getName()]))
 				{
-					throw new \Exception("Variables and parameters cannot share the same name.");
+					throw new \Exception('Variables and parameters cannot share the same name.');
 				}
 				$nodes[$variable_node->getName()] = $variable_node;
 				$graph->add($variable_node->getName(), $this->pass_1_getDependencies($variable_node));
@@ -230,7 +250,7 @@ class Compiler implements \App\Engine\ICompile
 					$options->setParameter($parameter_node->getName(), Node::toPhp($parameter_node));
 				}
 			}
-			else if ($type == 'variables')
+			elseif ($type == 'variables')
 			{
 				$variable_node = $variables_node->getChildByName($node_name);
 				if (isset($variable_node))
@@ -269,7 +289,7 @@ class Compiler implements \App\Engine\ICompile
 			{
 				$variables[] = $node->getValue();
 			}
-			else if ($node instanceof NodeFunctionValue &&
+			elseif ($node instanceof NodeFunctionValue &&
 				$node->getName() == 'param')
 			{
 				$variables[] = $node->getValue();