implemented plugin system and first example plugin, which now provides

the "title" functionality

css/solid.scss

-/*!
- * Font Awesome Free 5.8.1 by @fontawesome - https://fontawesome.com
- * License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License)
- */
-@import '../../Teamprojekt SLCMS/fontawesome-free-5.8.1-web/scss/variables';
-
-@font-face {
-  font-family: 'Font Awesome 5 Free';
-  font-style: normal;
-  font-weight: 900;
-  font-display: $fa-font-display;
-  src: url('#{$fa-font-path}/fa-solid-900.eot');
-  src: url('#{$fa-font-path}/fa-solid-900.eot?#iefix') format('embedded-opentype'),
-  url('#{$fa-font-path}/fa-solid-900.woff2') format('woff2'),
-  url('#{$fa-font-path}/fa-solid-900.woff') format('woff'),
-  url('#{$fa-font-path}/fa-solid-900.ttf') format('truetype'),
-  url('#{$fa-font-path}/fa-solid-900.svg#fontawesome') format('svg');
-}
-
-.fa,
-.fas {
-  font-family: 'Font Awesome 5 Free';
-  font-weight: 900;
-}

plugins/DynamicTitle/DynamicTitle.php

+<?php
+
+namespace DynamicTitle;
+
+use slcms\plugins\Plugin;
+
+class DynamicTitle extends Plugin {
+	const DEFAULT_TITLE = "Suckless CMS";
+
+	protected function init() {
+		$this->utils->registerSimplePlaceholder("title", $this->title());
+		$this->utils->registerComplexPlaceholder("subtitle", [&$this, "subtitle"]);
+	}
+
+	private function title() : string {
+		$titleFile = __DIR__."/../webcontent/.title";
+		if (file_exists($titleFile))
+			return (trim(strip_tags(file_get_contents($titleFile))));
+
+		return self::DEFAULT_TITLE;
+	}
+
+	public function subtitle($model) {
+		return $model->path === "" ? "Startseite" : \slcms\Std::getToplevelFromPath($model->path);
+	}
+}

src/Application.php

@@ -13,6 +13,8 @@ use slcms\models\Page;
  * @autor Michael Ochmann
  */
 class Application {
+	private $utils;
+	private $pluginManager;
 	private $dirTree;
 	private $renderer;
 	private $page;
@@ -20,10 +22,12 @@ class Application {
 
 	// builds the frame and puts out the time which was needed for
 	public function __construct() {
-		$this->startTime = microtime(true); // sets startTime on current Time
-		$this->dirTree   = new models\Tree("/".$_GET["path"]);
-		$this->page      = new Page($_GET["path"], $this->dirTree);
-		$this->renderer  = new Renderer($this->page);
+		$this->utils         = new plugins\Utils();
+		$this->pluginManager = new plugins\PluginManager($this->utils);
+		$this->startTime     = microtime(true); // sets startTime on current Time
+		$this->dirTree       = new models\Tree("/".$_GET["path"]);
+		$this->page          = new Page($_GET["path"], $this->dirTree, $this->utils);
+		$this->renderer      = new Renderer($this->page);
 
 		$this->renderer->render();
 		$microseconds = microtime(true) - $this->startTime; // counts microseconds until rendering is finished

src/models/Page.php

@@ -27,11 +27,12 @@ class Page implements Model {
 	public $texts;
 	public $others;
 	public $subtree;
-	private $path;
+	public $path;
 	private $stats;
-	private $subtitle;
+	private $utils;
 
-	public function __construct(string $path, Tree &$pageTree) {
+	public function __construct(string $path, Tree &$pageTree, \slcms\plugins\Utils &$utils) {
+		$this->utils   = $utils;
 		$this->images  = new SegmentedList();
 		$this->texts   = new SegmentedList();
 		$this->others  = new SegmentedList();
@@ -41,6 +42,14 @@ class Page implements Model {
 		$this->subtree = $pageTree->subtree();
 		$this->stats   = new PageStats();
 		$this->curateContents();
+
+		foreach ($utils->simplePlaceholders() as $key => $value) {
+			$this->$key = $value;
+		}
+
+		foreach ($utils->placeholders() as $key => $callback) {
+			$this->$key = $callback($this);
+		}
 	}
 
 	private function curateContents() : void {
@@ -94,18 +103,6 @@ class Page implements Model {
 		return count($this->texts);
 	}
 
-	public function title() : string {
-		$titleFile = __DIR__."/../../webcontent/.title";
-		if (file_exists($titleFile))
-			return (trim(strip_tags(file_get_contents($titleFile))));
-
-		// default name if there's no .title file
-		return "Suckless CMS";
-	}
-
-	public function subtitle() {
-		return $this->path === "" ? "Startseite" : \slcms\Std::getToplevelFromPath($this->path);
-	}
 
 	// getter for PageStats
 	public function maxImageWidth() : int {

src/plugins/Plugin.php

+<?php
+
+namespace slcms\plugins;
+
+abstract class Plugin {
+	protected $utils;
+
+	public function __construct(\slcms\plugins\Utils &$utils) {
+		$this->utils = $utils;
+		$this->init();
+	}
+
+	abstract protected function init();
+}

src/plugins/PluginManager.php

+<?php declare(strict_types=1);
+
+namespace slcms\plugins;
+
+class PluginManager {
+	private $utils;
+	private $pluginsLoaded;
+	private $plugins;
+
+	public function __construct(Utils &$utils) {
+		$this->utils         = $utils;
+		$this->pluginsLoaded = [];
+		$this->plugins       = [];
+		spl_autoload_register([&$this, "autoload"]);
+		$this->init();
+	}
+
+	private function init() {
+		$dir = dirname(__FILE__)."/../../plugins";
+		foreach (scandir($dir) as $plugin) {
+			if (!is_dir($dir."/".$plugin) || $plugin === "." ||$plugin === "..")
+				continue;
+			$class = "\\$plugin\\$plugin";
+			array_push($this->plugins, new $class($this->utils));
+		}
+	}
+
+	public function autoload(string $className) : void {
+		$pluginID  = $className;
+		$className = dirname(__FILE__)."/../../plugins/".str_replace("\\", "/", $className).".php";
+		if (file_exists($className)) {
+			require_once($className);
+			array_push($this->pluginsLoaded, $pluginID);
+		}
+	}
+
+	public function pluginsLoaded() : array {
+		return $this->pluginsLoaded;
+	}
+}

src/plugins/Utils.php

+<?php declare(strict_types=1);
+
+namespace slcms\plugins {
+
+	class Utils {
+		private $simplePlaceholders;
+		private $placeholders;
+
+		public function __construct() {
+			$this->placeholders       = [];
+			$this->simplePlaceholders = [];
+		}
+
+		public function simplePlaceholders() : array {
+			return $this->simplePlaceholders;
+		}
+
+		public function placeholders() : array {
+			return $this->placeholders;
+		}
+
+		public function registerSimplePlaceholder(string $identifier, $value) : bool {
+			if (array_key_exists($identifier, $this->simplePlaceholders) || array_key_exists($identifier, $this->placeholders))
+				return false;
+			$this->simplePlaceholders[$identifier] = $value;
+
+			return true;
+		}
+
+		public function registerComplexPlaceholder(string $identifier, callable $callback) : bool {
+			if (array_key_exists($identifier, $this->simplePlaceholders) || array_key_exists($identifier, $this->placeholders))
+				return false;
+			$this->placeholders[$identifier] = $callback;
+
+			return true;
+		}
+	}
+
+}