Flesh out engine + compile interface, add no-op compiler

app/Engine/Cfnpp.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Engine;
+
+use App\Dom\Document;
+
+class Cfnpp implements ICompile
+{
+	/** @var Document */
+	protected $document;
+
+	public function setDocument(Document $document): void
+	{
+		$this->document = $document;
+	}
+
+	public function compile(Document $document, IOptions $options): void
+	{
+		// noop
+	}
+
+	public function getDocument(): Document
+	{
+		return $this->document;
+	}
+}

app/Engine/Engine.php

@@ -20,6 +20,9 @@ class Engine
 	/** @var \App\Serialize\IUnserialize */
 	protected $unserialize;
 
+	/** @var \App\Dom\Document */
+	protected $document;
+
 	public function setCompiler(ICompile $compiler): Engine
 	{
 		$this->compile = $compiler;
@@ -38,15 +41,40 @@ class Engine
 		return $this;
 	}
 
-	public function compile(string $document_string, IOptions $options): string
+	public function setInputDocument(\App\Dom\Document $document): Engine
+	{
+		$this->document = $document;
+		$this->compile->setDocument($document);
+		return $this;
+	}
+
+	public function setInput(string $document_string): Engine
 	{
 		$document = $this->unserialize->unserialize($document_string);
-		$document = $this->compile->compile($document, $options);
-		return $this->serialize->serialize($document);
+		$this->setInputDocument($document);
+		return $this;
 	}
 
-	public function compileDocument(\App\Dom\Document $document, IOptions $options): \App\Dom\Document
+	public function compile(string $document_string, IOptions $options): Engine
+	{
+		$document = $this->unserialize->unserialize($document_string);
+		$this->compileDocument($document, $options);
+		return $this;
+	}
+
+	public function compileDocument(\App\Dom\Document $document, IOptions $options): Engine
 	{
 		return $this->compile->compile($document, $options);
 	}
+
+	public function getOutputDocument(): \App\Dom\Document
+	{
+		return $this->compile->getDocument();
+	}
+
+	public function getOutput(): string
+	{
+		$document = $this->getOutputDocument();
+		return $this->serialize->serialize($document);
+	}
 }

app/Engine/ICompile.php

@@ -12,11 +12,27 @@ namespace App\Engine;
 interface ICompile
 {
 	/**
-	 * Perform compilation/transform process on a document.
+	 * Set the base document all our compilations are run against.
+	 *
+	 * @param  \App\Dom\Document $document
+	 * @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
 	 * @param  IOptions          $options  options to control compilation process
-	 * @return \App\Dom\Document the compiled document
+	 * @return void
+	 */
+	public function compile(\App\Dom\Document $document, IOptions $options): void;
+
+	/**
+	 * Retrieve the current result.
+	 *
+	 * @return \App\Dom\Document
 	 */
-	public function compile(\App\Dom\Document $document, IOptions $options): \App\Dom\Document;
+	public function getDocument(): \App\Dom\Document;
 }