fix(autoload): register fallback autoload as needed (#255)

x-ref #254

CHANGELOG.md

@@ -1,3 +1,6 @@
+### 4.0.1: August 31st, 2020
+* Add fallback autoloader when Composer isn't present
+
 ### 4.0.0: August 29th, 2020
 * BREAKING CHANGE - Refactor entire code base
 * Add options support for modules

soil.php

@@ -4,7 +4,7 @@
  * Plugin Name:        Soil
  * Plugin URI:         https://roots.io/plugins/soil/
  * Description:        A collection of modules to apply theme-agnostic front-end modifications to WordPress.
- * Version:            4.0.0
+ * Version:            4.0.1
  * Author:             Roots
  * Author URI:         https://roots.io/
  * GitHub Plugin URI:  https://github.com/roots/soil
@@ -15,9 +15,13 @@
 
 namespace Roots\Soil;
 
-require_once __DIR__ . '/vendor/autoload.php';
-
 add_action('plugins_loaded', function () {
+    if (!class_exists(Soil::class)) {
+        require_once file_exists($autoloader = __DIR__ . '/vendor/autoload.php')
+            ? $autoloader
+            : __DIR__ . '/src/autoload.php';
+    }
+
     $modules = Soil::discoverModules();
 
     add_action('after_setup_theme', new Soil($modules), 100);

src/autoload.php

@@ -0,0 +1,13 @@
+<?php
+
+require_once __DIR__ . '/helpers.php';
+
+spl_autoload_register(function ($className) {
+    $relativeClassName = array_slice(explode('\\', $className), 2);
+    $file = __DIR__ . DIRECTORY_SEPARATOR . implode(DIRECTORY_SEPARATOR, $relativeClassName) . '.php';
+    if (file_exists($file)) {
+        require $file;
+        return true;
+    }
+    return false;
+});