Have the compiler passed the entire set of documents + state to facilitate moving the higher-level compilation logic into the compiler

We're moving a bunch of the compilation logic building up inside Engine into the compiler

app/Engine/Cfnpp.php

@@ -16,12 +16,6 @@ use App\Dom\NodeFunction;
  */
 class Cfnpp implements ICompile
 {
-	/**
-	 * Current document state.
-	 * @var Document
-	 */
-	protected $document;
-
 	/**
 	 * Functions that can be called by the document.
 	 *
@@ -44,20 +38,6 @@ class Cfnpp implements ICompile
 	 */
 	protected $merge_functions;
 
-	public function __construct(IOptions $options)
-	{
-		if (!($options instanceof CfnppOptions))
-		{
-			throw new \Exception('Cfnpp compiler requires CfnppOptions');
-		}
-
-		$this->document = new Document();
-		$this->functions = [];
-
-		$cfnpp_functions = new CfnppFunctions($this, $options);
-		$cfnpp_functions->register($this);
-	}
-
 	/**
 	 * Register a function that can be called by the document.
 	 *
@@ -84,37 +64,37 @@ class Cfnpp implements ICompile
 	}
 
 	/**
-	 * Set the current state that new compilations will be applied to.
+	 * Compile a set of documents and return the result.
 	 *
-	 * @param  Document $document
+	 * @param  Document[] $documents
+	 * @param  IOptions   $options
 	 * @return void
 	 */
-	public function setDocument(Document $document): void
+	public function compile(array $documents, IOptions $options): Document
 	{
-		$this->document = $document;
-	}
+		if (!($options instanceof CfnppOptions))
+		{
+			throw new \Exception('Cfnpp compiler requires CfnppOptions');
+		}
 
-	/**
-	 * Get the document representing the current state.
-	 *
-	 * @return Document
-	 */
-	public function getDocument(): Document
-	{
-		return $this->document;
-	}
+		// Initialize state
+		$document = new Document();
+		$this->functions = [];
+		$this->merge_functions = [];
 
-	/**
-	 * Apply a new document to the current state.
-	 *
-	 * @param  Document $document
-	 * @return void
-	 */
-	public function compile(Document $document): void
-	{
-		$this->runMergeFunctions($this->document, $document);
-		$this->merge($this->document, $document);
-		$this->runFunctions($this->document);
+		// Register built-in functions
+		$cfnpp_functions = new CfnppFunctions($this, $options);
+		$cfnpp_functions->register($this);
+
+		// Process each passed document
+		foreach ($documents as $next_document)
+		{
+			$this->runMergeFunctions($document, $next_document);
+			$this->merge($document, $next_document);
+			$this->runFunctions($document);
+		}
+
+		return $document;
 	}
 
 	/**

app/Engine/ICompile.php

@@ -12,26 +12,11 @@ namespace App\Engine;
 interface ICompile
 {
 	/**
-	 * Set the base document all our compilations are run against.
+	 * Given a set of documents, perform all compilation steps and return the result.
 	 *
-	 * @param  \App\Dom\Document $document
+	 * @param  \App\Dom\Document[] $documents documents to compile
+	 * @param  IOptions            $options
 	 * @return void
 	 */
-	public function setDocument(\App\Dom\Document $document): void;
-
-	/**
-	 * Perform transform process on the document held by this class,
-	 * using the one passed in as instructions.
-	 *
-	 * @param  \App\Dom\Document $document document to compile
-	 * @return void
-	 */
-	public function compile(\App\Dom\Document $document): void;
-
-	/**
-	 * Retrieve the current result.
-	 *
-	 * @return \App\Dom\Document
-	 */
-	public function getDocument(): \App\Dom\Document;
+	public function compile(array $documents, IOptions $options): \App\Dom\Document;
 }