added proper resolving of config dependencies with Resolver class

src/Builder.php

@@ -125,6 +125,8 @@ public function buildConfigs($files = null)
         if (is_null($files)) {
             $files = $this->files;
         }
+        $resolver = new Resolver($files);
+        $files = $resolver->get();
         foreach ($files as $name => $paths) {
             $olddefs = get_defined_constants();
             $configs = $this->loadConfigs($paths);

src/Plugin.php

@@ -263,15 +263,15 @@ protected function prepareAliases(PackageInterface $package, $psr, $dev = false)
      */
     public function preparePath(PackageInterface $package, $path)
     {
+        if (strncmp($path, '$', 1) === 0) {
+            return $path;
+        }
+
         $skippable = strncmp($path, '?', 1) === 0 ? '?' : '';
         if ($skippable) {
             $path = substr($path, 1);
         }
 
-        if (strncmp($path, '$', 1) === 0) {
-            $path = Builder::path(substr($path, 1));
-        }
-
         if (!$this->getFilesystem()->isAbsolutePath($path)) {
             $prefix = $package instanceof RootPackageInterface
                 ? $this->getBaseDir()

src/Resolver.php

@@ -0,0 +1,100 @@
+<?php
+/**
+ * Composer plugin for config assembling
+ *
+ * @link      https://github.com/hiqdev/composer-config-plugin
+ * @package   composer-config-plugin
+ * @license   BSD-3-Clause
+ * @copyright Copyright (c) 2016-2017, HiQDev (http://hiqdev.com/)
+ */
+
+namespace hiqdev\composer\config;
+
+use hiqdev\composer\config\exceptions\CircularDependencyException;
+
+/**
+ * Resolver class.
+ * Reorders files according to their cross dependencies
+ * and resolves `$name` pathes.
+ * @author Andrii Vasyliev <sol@hiqdev.com>
+ */
+class Resolver
+{
+    protected $order = [];
+
+    protected $deps = [];
+
+    protected $following = [];
+
+    public function __construct(array $files)
+    {
+        $this->files = $files;
+
+        $this->collectDeps();
+        foreach (array_keys($this->files) as $name) {
+            $this->followDeps($name);
+        }
+
+    }
+
+    public function get()
+    {
+        $result = [];
+        foreach ($this->order as $name) {
+            $result[$name] = $this->resolveDeps($this->files[$name]);
+        }
+
+        return $result;
+    }
+
+    protected function resolveDeps(array $paths)
+    {
+        foreach ($paths as &$path) {
+            $dep = $this->isDep($path);
+            if ($dep) {
+                $path = Builder::path($dep);
+            }
+        }
+
+        return $paths;
+    }
+
+    protected function followDeps($name)
+    {
+        if (isset($this->order[$name])) {
+            return;
+        }
+        if (isset($this->following[$name])) {
+            throw new CircularDependencyException($name . ' ' . implode(',', $this->following));
+        }
+        $this->following[$name] = $name;
+        if (isset($this->deps[$name])) {
+            foreach ($this->deps[$name] as $dep) {
+                $this->followDeps($dep);
+            }
+        }
+        $this->order[$name] = $name;
+        unset($this->following[$name]);
+    }
+
+    protected function collectDeps()
+    {
+        foreach ($this->files as $name => $paths) {
+            foreach ($paths as $path) {
+                $dep = $this->isDep($path);
+                if ($dep) {
+                    if (!isset($this->deps[$name])) {
+                        $this->deps[$name] = [];
+                    }
+                    $this->deps[$name][$dep] = $dep;
+                }
+            }
+        }
+    }
+
+    protected function isDep($path)
+    {
+        return strncmp($path, '$', 1) === 0 ? substr($path, 1) : false;
+    }
+
+}

src/exceptions/CircularDependencyException.php

@@ -0,0 +1,19 @@
+<?php
+/**
+ * Composer plugin for config assembling
+ *
+ * @link      https://github.com/hiqdev/composer-config-plugin
+ * @package   composer-config-plugin
+ * @license   BSD-3-Clause
+ * @copyright Copyright (c) 2016-2017, HiQDev (http://hiqdev.com/)
+ */
+
+namespace hiqdev\composer\config\exceptions;
+
+/**
+ * Circular dependency exception.
+ * @author Andrii Vasyliev <sol@hiqdev.com>
+ */
+class CircularDependencyException extends Exception
+{
+}