Expression bug fix replacing variables; add string literal

app/Cfnpp/Expression/Expression.php

@@ -13,6 +13,7 @@ class Expression
 		Token\NumericLiteral::class,
 		Token\OperatorUnary::class,
 		Token\OperatorBinary::class,
+		Token\StringLiteral::class,
 		Token\Variable::class
 	];
 
@@ -48,6 +49,16 @@ class Expression
 		return $complete;
 	}
 
+	public function count()
+	{
+		return sizeof($this->nodes);
+	}
+
+	public function getValue()
+	{
+		return $this->nodes[0]->getValue();
+	}
+
 	public function toArray(): array
 	{
 		return static::unwrap($this->nodes);
@@ -111,11 +122,16 @@ class Expression
 		return $stack->get();
 	}
 
-	protected static function solve(array $nodes, array $variables = [], array $parameters = [])
+	protected static function solve(array $nodes, array $variables = [], array $parameters = []): array
 	{
-		static::fillVariables($nodes, $variables, $parameters);
-		static::collapse($nodes);
-		return $nodes;
+		$root = new GraphNode();
+		foreach ($nodes as $node)
+		{
+			$root->appendChild($node);
+		}
+		$nodes = static::fillVariables($root->getChildren(), $variables, $parameters);
+		$nodes = static::collapse($root->getChildren());
+		return $root->getChildren();
 	}
 
 	protected static function execute(array $nodes, array $variables = [], array $parameters = [])
@@ -128,6 +144,10 @@ class Expression
 		foreach ($nodes as $node)
 		{
 			$node->walk(static function($node) {
+				if (is_scalar($node->getValue()))
+				{
+					return;
+				}
 				if (!($node->getValue() instanceof ICloudformationNative))
 				{
 					throw new \Exception('Token '.basename(get_class($node->getValue())).' is not natively supported by CloudFormation.');
@@ -144,7 +164,7 @@ class Expression
 		return $nodes[0]->getValue();
 	}
 
-	protected static function fillVariables(array $nodes, array $variables, array $parameters)
+	protected static function fillVariables(array $nodes, array $variables, array $parameters): void
 	{
 		foreach ($nodes as $node)
 		{
@@ -169,7 +189,7 @@ class Expression
 		}
 	}
 
-	protected static function collapse(array $nodes)
+	protected static function collapse(array $nodes): void
 	{
 		foreach ($nodes as $node)
 		{

app/Cfnpp/Expression/Token/StringLiteral.php

@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Cfnpp\Expression\Token;
+
+use App\Cfnpp\Expression\Token;
+use App\Cfnpp\Expression\TokenLiteral;
+
+class StringLiteral extends TokenLiteral
+{
+	protected $value;
+
+	public function __construct($value)
+	{
+		$this->value = $value;
+	}
+
+	public function getValue()
+	{
+		return $this->value;
+	}
+
+	public static function isToken(string $stream): bool
+	{
+		return $stream[0] == '"';
+	}
+
+	public static function getToken(string &$stream): Token
+	{
+		$buffer = '';
+		$in_string = false;
+		$escaped = false;
+
+		for ($i = 0; $i < strlen($stream); $i++)
+		{
+			if ($escaped)
+			{
+				$buffer .= $stream[$i];
+				$escaped = false;
+			}
+			elseif ($stream[$i] == '"')
+			{
+				if ($in_string)
+				{
+					break;
+				}
+
+				$in_string = true;
+			}
+			elseif ($stream[$i] == '\\')
+			{
+				$escaped = true;
+			}
+			else
+			{
+				$buffer .= $stream[$i];
+			}
+		}
+
+		$stream = substr($stream, $i + 1);
+
+		return new StringLiteral($buffer);
+	}
+
+	public function execute(?array $arguments = null)
+	{
+		return $this->getValue();
+	}
+}