Cleanup

app/Cfnpp/Compiler.php

@@ -296,7 +296,7 @@ class Compiler implements \App\Engine\ICompile
 			elseif ($node instanceof NodeFunctionValue &&
 				$node->getName() == 'expr')
 			{
-				$expression = new \App\Cfnpp\Expression\Expression($node->getValue(), $options);
+				$expression = new \App\Cfnpp\Expression\Expression($node->getValue());
 				$variables = array_merge($variables, $expression->getReferencedVariables());
 			}
 		}

app/Cfnpp/Expression/Expression.php

@@ -46,7 +46,6 @@ class Expression
 	 * Expression is tokenized, parsed, and solved on creation.
 	 *
 	 * @param string               $expression
-	 * @param \App\Engine\IOptions $options
 	 */
 	public function __construct(string $expression)
 	{
@@ -54,7 +53,13 @@ class Expression
 		$this->nodes = static::parse($tokens);
 	}
 
-	public function solve(\App\Engine\IOptions $options)
+	/**
+	 * Solve this expression down to the minimal set of nodes we can
+	 *
+	 * @param \App\Engine\IOptions $options
+	 * @return void
+	 */
+	public function solve(\App\Engine\IOptions $options): void
 	{
 		$this->nodes = static::_solve($this->nodes, $options->getVariables(), array_keys($options->getParameters()));
 	}
@@ -142,7 +147,7 @@ class Expression
 		$variables = [];
 		foreach ($this->nodes as $node)
 		{
-			$node->walk(function($node) use (&$variables) {
+			$node->walk(function(GraphNode $node) use (&$variables): void {
 				if ($node->getValue() instanceof Token\Variable)
 				{
 					$variables[] = $node->getValue()->getName();