diff --git a/src/Plugin.php b/src/Plugin.php
index 7d6b9d9..0ebe534 100644
--- a/src/Plugin.php
+++ b/src/Plugin.php
@@ -113,9 +113,9 @@ abstract class Plugin implements PluginInterface
     /**
      * {@inheritDoc}
      */
-    public function getConfig(string $key)
+    public function getConfig(string $key, $default)
     {
-        return $this->config[$key];
+        return $this->config[$key] ?? $default;
     }
     /**
      * {@inheritDoc}
@@ -127,14 +127,28 @@ abstract class Plugin implements PluginInterface
     /**
      * {@inheritDoc}
      */
-    public function needs()
+    public static function mergeConfigs(array ...$configs): array
+    {
+        return $configs;
+    }
+    /**
+     * {@inheritDoc}
+     */
+    public static function composerRequires(): array
     {
         return [];
     }
     /**
      * {@inheritDoc}
      */
-    public function extends()
+    public static function needs(): array
+    {
+        return [];
+    }
+    /**
+     * {@inheritDoc}
+     */
+    public static function extends(): array
     {
         return [];
     }
diff --git a/src/Target/Php56/YieldFromReplacer.php b/src/Plugin/Amp/YieldFromReplacer.php
similarity index 100%
rename from src/Target/Php56/YieldFromReplacer.php
rename to src/Plugin/Amp/YieldFromReplacer.php
diff --git a/src/Target/Php56/YieldReturnDetector.php b/src/Plugin/Amp/YieldReturnDetector.php
similarity index 100%
rename from src/Target/Php56/YieldReturnDetector.php
rename to src/Plugin/Amp/YieldReturnDetector.php
diff --git a/src/Target/Php56/YieldReturnReplacer.php b/src/Plugin/Amp/YieldReturnReplacer.php
similarity index 100%
rename from src/Target/Php56/YieldReturnReplacer.php
rename to src/Plugin/Amp/YieldReturnReplacer.php
diff --git a/src/Plugin/TypeHintStripper.php b/src/Plugin/TypeHintStripper.php
index a882f38..d574556 100644
--- a/src/Plugin/TypeHintStripper.php
+++ b/src/Plugin/TypeHintStripper.php
@@ -26,13 +26,12 @@ class TypeHintStripper extends Plugin
         if (!$type || $type instanceof UnionType) {
             return;
         }
-        if ($type instanceof NullableType && $this->getConfig('nullable')) {
+        if ($type instanceof NullableType && $this->getConfig('nullable', false)) {
             $type = null;
             return;
         }
         $throwableType = $type instanceof NullableType ? $type->type : $type;
-        // Make this less ugly when we implement a namespace context
-        if (\in_array($throwableType->toString(), $this->getConfig('types'))) {
+        if (\in_array($throwableType->toString(), $this->getConfig('types', []))) {
             $type = null;
         }
     }
diff --git a/src/PluginGraph/Graph.php b/src/PluginGraph/Graph.php
new file mode 100644
index 0000000..2956fab
--- /dev/null
+++ b/src/PluginGraph/Graph.php
@@ -0,0 +1,75 @@
+<?php
+
+namespace Phabel\PluginGraph;
+
+use Phabel\PluginInterface;
+
+class Graph
+{
+    /**
+     * Plugin nodes, indexed by plugin name+config.
+     *
+     * @var array<class-string<PluginInterface>, array<string, Node>>
+     */
+    private array $plugins = [];
+
+    /**
+     * Package contexts.
+     *
+     * @var PackageContext[]
+     */
+    private array $packageContexts = [];
+
+    /**
+     * Get new package context.
+     *
+     * @return PackageContext
+     */
+    public function getPackageContext(): PackageContext
+    {
+        $packageContext = new PackageContext;
+        $this->packageContexts []= $packageContext;
+        return $packageContext;
+    }
+
+    /**
+     * Add plugin.
+     *
+     * @param string         $plugin Plugin to add
+     * @param array          $config Plugin configuration
+     * @param PackageContext $ctx    Package context
+     *
+     * @psalm-param class-string<PluginInterface> $plugin Plugin name
+     *
+     * @return Node[]
+     */
+    public function addPlugin(string $plugin, array $config, PackageContext $ctx): array
+    {
+        $configs = $plugin::splitConfig($config);
+        $nodes = [];
+        foreach ($configs as $config) {
+            $nodes []= $this->addPluginInternal($plugin, $config, $ctx);
+        }
+        return $nodes;
+    }
+    /**
+     * Add plugin.
+     *
+     * @param string         $plugin Plugin to add
+     * @param array          $config Plugin configuration
+     * @param PackageContext $ctx    Package context
+     *
+     * @psalm-param class-string<PluginInterface> $plugin Plugin name
+     *
+     * @return Node
+     */
+    private function addPluginInternal(string $plugin, array $config, PackageContext $ctx): Node
+    {
+        $configStr = \var_export($config, true);
+        if (isset($this->plugins[$plugin][$configStr])) {
+            return $this->plugins[$plugin][$configStr]->addPackageContext($ctx);
+        }
+        $this->plugins[$plugin][$configStr] = $node = new Node;
+        return $node->init($this, $plugin, $config, $ctx);
+    }
+}
diff --git a/src/PluginGraph/Node.php b/src/PluginGraph/Node.php
new file mode 100644
index 0000000..e370e8e
--- /dev/null
+++ b/src/PluginGraph/Node.php
@@ -0,0 +1,159 @@
+<?php
+
+namespace Phabel\PluginGraph;
+
+use Phabel\PluginInterface;
+use SplObjectStorage;
+
+/**
+ * Represents a plugin with a certain configuration.
+ */
+class Node
+{
+    /**
+     * Plugin name.
+     */
+    private string $plugin = '';
+    /**
+     * Plugin configuration.
+     */
+    private array $config = [];
+
+    /**
+     * Associated package contexts.
+     */
+    private SplObjectStorage $packageContexts;
+    /**
+     * Nodes that this node requires.
+     *
+     * @var Node[]
+     */
+    private array $requires = [];
+
+    /**
+     * Nodes that this node extends.
+     *
+     * @var Node[]
+     */
+    private array $extends = [];
+
+    /**
+     * Nodes that require this node.
+     *
+     * @var Node[]
+     */
+    private array $requiredBy = [];
+
+    /**
+     * Nodes that extend this node.
+     *
+     * @var Node[]
+     */
+    private array $extendedBy = [];
+
+    /**
+     * Whether this node was visited when looking for circular requirement references.
+     */
+    private bool $visitedRequires = false;
+    /**
+     * Whether this node was visited when looking for circular requirement references.
+     */
+    private bool $visitedExtends = false;
+
+    /**
+     * Constructor.
+     */
+    public function __construct()
+    {
+        $this->packageContexts = new SplObjectStorage;
+    }
+    /**
+     * Initialization function.
+     *
+     * @param Graph          $graph  Graph instance
+     * @param string         $plugin Plugin name
+     * @param array          $config Plugin configuration
+     * @param PackageContext $ctx    Context
+     *
+     * @psalm-param class-string<PluginInterface> $plugin Plugin name
+     *
+     * @return self
+     */
+    public function init(Graph $graph, string $plugin, array $config, PackageContext $ctx): self
+    {
+        $this->plugin = $plugin;
+        $this->config = $config;
+        $this->packageContexts->attach($ctx);
+
+        $requirements = self::simplify($plugin::needs());
+        $extends = self::simplify($plugin::extends());
+
+        foreach ($requirements as $class => $config) {
+            foreach ($graph->addPlugin($class, $config, $ctx) as $node) {
+                $this->requires []= $node;
+                $node->requiredBy []= $this;
+            }
+        }
+        foreach ($extends as $class => $config) {
+            foreach ($graph->addPlugin($class, $config, $ctx) as $node) {
+                $this->extends []= $node;
+                $node->extendedBy []= $this;
+            }
+        }
+
+        return $this;
+    }
+
+    /**
+     * Simplify requirements.
+     *
+     * @param (array<class-string<PluginInterface>, array>|class-string<PluginInterface>[]) $requirements Requirements
+     *
+     * @return array<class-string<PluginInterface>, array>
+     */
+    private static function simplify(array $requirements): array
+    {
+        return isset($requirements[0]) ? \array_fill_keys($requirements, []) : $requirements;
+    }
+
+    /**
+     * Add package context.
+     *
+     * @param PackageContext $ctx Context
+     *
+     * @return self
+     */
+    public function addPackageContext(PackageContext $ctx): self
+    {
+        if ($this->packageContexts->contains($ctx)) {
+            return $this;
+        }
+        $this->packageContexts->attach($ctx);
+        foreach ($this->requires as $node) {
+            $node->addPackageContext($ctx);
+        }
+        foreach ($this->extends as $node) {
+            $node->addPackageContext($ctx);
+        }
+        return $this;
+    }
+
+    /**
+     * Check if this node requires only one other node.
+     *
+     * @return boolean
+     */
+    private function oneRequire(): bool
+    {
+        return \count($this->requires) === 1 && empty($this->extends);
+    }
+    /**
+     * Check if this node extends only one other node.
+     *
+     * @return boolean
+     */
+    private function oneExtend(): bool
+    {
+        return \count($this->extends) === 1;
+    }
+}
diff --git a/src/PluginGraph/PackageContext.php b/src/PluginGraph/PackageContext.php
new file mode 100644
index 0000000..afb1709
--- /dev/null
+++ b/src/PluginGraph/PackageContext.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Phabel\PluginGraph;
+
+/**
+ * List of packages associated with plugin.
+ */
+class PackageContext
+{
+    /**
+     * Package list.
+     *
+     * @var array<string, null>
+     */
+    private array $packages = [];
+    /**
+     * Add package.
+     *
+     * @param string $package Package
+     *
+     * @return void
+     */
+    public function addPackage(string $package): void
+    {
+        $this->packages[$package] = null;
+    }
+    /**
+     * Merge two contexts
+     *
+     * @param self $other Other context
+     * 
+     * @return self New context
+     */
+    public function merge(self $other): self
+    {
+        $this->packages += $other->packages;
+        return $this;
+    }
+
+    /**
+     * Get package list
+     *
+     * @return array
+     */
+    public function getPackages(): array
+    {
+        return array_values($this->packages);
+    }
+}
diff --git a/src/PluginInterface.php b/src/PluginInterface.php
index ef2aeb9..e11d812 100644
--- a/src/PluginInterface.php
+++ b/src/PluginInterface.php
@@ -2,8 +2,6 @@
 
 namespace Phabel;
 
-use PhpParser\NodeVisitor;
-
 interface PluginInterface
 {
     /**
@@ -14,40 +12,67 @@ interface PluginInterface
      *
      * When possible, use the extends method to reduce complexity.
      *
-     * @return array|string Plugin name(s)
+     * @return array Plugin name(s)
      *
-     * @psalm-return array<class-string<Plugin|NodeVisitor>>|class-string<Plugin|NodeVisitor>
+     * @psalm-return class-string<PluginInterface>[]|array<class-string<PluginInterface>, array>
      */
-    public function needs();
+    public static function needs(): array;
     /**
-     * Specify which plugins does this plugin extends.
+     * Specify which plugins does this plugin extend.
      *
      * At each depth level, the traverser will first execute the enter|leave methods of the specified plugins, then immediately execute the enter|leave methods of the current plugin.
      *
      * This is preferred, and allows only a single traversal of the AST.
      *
-     * @return array|string Plugin name(s)
+     * @return array Plugin name(s)
      *
-     * @psalm-return array<class-string<Plugin|NodeVisitor>>|class-string<Plugin|NodeVisitor>
+     * @psalm-return class-string<PluginInterface>[]|array<class-string<PluginInterface>, array>
      */
-    public function extends();
+    public static function extends(): array;
 
     /**
-     * Get configuration key
+     * Specify a list of composer dependencies.
+     *
+     * @return array
+     */
+    public static function composerRequires(): array;
+    /**
+     * Get configuration key.
+     *
+     * @param string $key     Key
+     * @param mixed  $default Default value, if key is not present
      *
-     * @param string $key Key
-     * 
      * @return mixed
      */
-    public function getConfig(string $key);
+    public function getConfig(string $key, $default);
 
     /**
-     * Set configuration key
+     * Set configuration key.
      *
      * @param string $key   Key
      * @param mixed  $value Value
-     * 
+     *
      * @return void
      */
     public function setConfig(string $key, $value): void;
+
+    /**
+     * Merge multiple configurations into one (or more).
+     *
+     * @param array ...$configs Configurations
+     *
+     * @return array[]
+     */
+    public static function mergeConfigs(array ...$configs): array;
+    /**
+     * Split configuration.
+     * 
+     * For example, if you have a configuration that enables feature A, B and C, return three configuration arrays each enabling ONLY A, only B and only C.
+     * This is used for optimizing the AST traversing process during resolution of the plugin graph.
+     *
+     * @param array $config Configuration
+     *
+     * @return array[]
+     */
+    public static function splitConfig(array $config): array;
 }
diff --git a/src/Target/Php56/MethodCallReplacer.php b/src/Target/Php56/MethodCallReplacer.php
deleted file mode 100644
index 6edb9f3..0000000
--- a/src/Target/Php56/MethodCallReplacer.php
+++ /dev/null
@@ -1,28 +0,0 @@
-<?php
-
-namespace Spatie\Php7to5\NodeVisitors;
-
-use PhpParser\Node;
-use PhpParser\NodeVisitorAbstract;
-
-class MethodCallReplacer extends NodeVisitorAbstract
-{
-    /**
-     * {@inheritdoc}
-     */
-    public function leaveNode(Node $node)
-    {
-        if (!$node instanceof Node\Expr\MethodCall) {
-            return;
-        }
-        $value = &$node->var;
-        if (!$value instanceof Node\Expr\Clone_ &&
-            !$value instanceof Node\Expr\Yield_ &&
-            !$value instanceof Node\Expr\Closure
-        ) {
-            return;
-        }
-        $value = new Node\Expr\FuncCall(new Node\Name('\\returnMe'), [$value]);
-        return $node;
-    }
-}
diff --git a/src/Target/Php70/CompoundAccess.php b/src/Target/Php70/CompoundAccess.php
index 6a56ef0..ac044c8 100644
--- a/src/Target/Php70/CompoundAccess.php
+++ b/src/Target/Php70/CompoundAccess.php
@@ -7,6 +7,7 @@ use PhpParser\Node;
 use PhpParser\Node\Expr\ArrayDimFetch;
 use PhpParser\Node\Expr\ClassConstFetch;
 use PhpParser\Node\Expr\Isset_;
+use PhpParser\Node\Expr\MethodCall;
 use PhpParser\Node\Expr\Yield_;
 
 /**
@@ -37,7 +38,7 @@ class CompoundAccess extends Plugin
      * Fix yield array access.
      *
      * @param ArrayDimFetch $node Node
-     * 
+     *
      * @return void
      */
     public function enterArrayYield(ArrayDimFetch $node): void
@@ -48,10 +49,10 @@ class CompoundAccess extends Plugin
         $node->var = self::callPoly('returnMe', $node->var);
     }
     /**
-     * Fix yield array access
+     * Fix yield array access.
      *
      * @param Yield_ $node Yield
-     * 
+     *
      * @return void
      */
     public function enterYield(Yield_ $node): void
@@ -61,10 +62,28 @@ class CompoundAccess extends Plugin
             return;
         }
         if ($value instanceof Node\Expr\FuncCall ||
-                $value instanceof Node\Expr\MethodCall ||
-                $value instanceof Node\Expr\StaticCall ||
-                $value instanceof Node\Scalar
-            ) {
+            $value instanceof Node\Expr\MethodCall ||
+            $value instanceof Node\Expr\StaticCall ||
+            $value instanceof Node\Scalar
+        ) {
+            return;
+        }
+        $value = self::callPoly('returnMe', $value);
+    }
+    /**
+     * Replace method call on yielded|cloned|closure object.
+     *
+     * @param MethodCall $node Method call
+     *
+     * @return void
+     */
+    public function enterMethodCall(MethodCall $node): void
+    {
+        $value = &$node->var;
+        if (!$value instanceof Node\Expr\Clone_ &&
+            !$value instanceof Node\Expr\Yield_ &&
+            !$value instanceof Node\Expr\Closure
+        ) {
             return;
         }
         $value = self::callPoly('returnMe', $value);
diff --git a/src/Target/Php70/NullCoalesceReplacer.php b/src/Target/Php70/NullCoalesceReplacer.php
index c8b70e8..f4aa4a2 100644
--- a/src/Target/Php70/NullCoalesceReplacer.php
+++ b/src/Target/Php70/NullCoalesceReplacer.php
@@ -10,10 +10,10 @@ use PhpParser\Node\Expr\StaticCall;
 class NullCoalesceReplacer extends Plugin
 {
     /**
-     * Replace null coalesce
+     * Replace null coalesce.
      *
      * @param Coalesce $node Coalesce
-     * 
+     *
      * @return StaticCall
      */
     public function enter(Coalesce $node): StaticCall
@@ -33,6 +33,6 @@ class NullCoalesceReplacer extends Plugin
      */
     public static function coalesce($ifNotNull, $then)
     {
-        return isset($ifNotNull) ?: $then;
+        return isset($ifNotNull) ? $ifNotNull : $then;
     }
 }
diff --git a/src/Target/Php70/ScalarTypeHintsRemover.php b/src/Target/Php70/ScalarTypeHintsRemover.php
index 2d4e216..5ddaa8c 100644
--- a/src/Target/Php70/ScalarTypeHintsRemover.php
+++ b/src/Target/Php70/ScalarTypeHintsRemover.php
@@ -12,7 +12,7 @@ class ScalarTypeHintsRemover extends Plugin
      *
      * @return array
      */
-    public function needs(): array
+    public static function needs(): array
     {
         return [
             TypeHintStripper::class => [
diff --git a/src/Target/Php70/ThrowableReplacer.php b/src/Target/Php70/ThrowableReplacer.php
index bc9cce1..d62c844 100644
--- a/src/Target/Php70/ThrowableReplacer.php
+++ b/src/Target/Php70/ThrowableReplacer.php
@@ -78,7 +78,7 @@ class ThrowableReplacer extends Plugin
      *
      * @return array
      */
-    public function extends(): array
+    public static function extends(): array
     {
         return [
             TypeHintStripper::class => [
diff --git a/src/Target/Php71/ClassConstantVisibilityModifiersRemover.php b/src/Target/Php71/ClassConstantVisibilityModifiersRemover.php
index 5848f83..ee72c61 100644
--- a/src/Target/Php71/ClassConstantVisibilityModifiersRemover.php
+++ b/src/Target/Php71/ClassConstantVisibilityModifiersRemover.php
@@ -3,10 +3,7 @@
 namespace Phabel\Target\Php71;
 
 use Phabel\Plugin;
-use PhpParser\Node\Expr;
-use PhpParser\Node\Expr\ClassConstFetch;
 use PhpParser\Node\Stmt\ClassConst;
-use PhpParser\NodeVisitor\NameResolver;
 
 /**
  * Removes the class constant visibility modifiers (PHP 7.1).
@@ -17,19 +14,11 @@ class ClassConstantVisibilityModifiersRemover extends Plugin
      * Makes public private and protected class constants.
      *
      * @param ClassConst $node Constant
-     * 
+     *
      * @return void
      */
     public function enter(ClassConst $node): void
     {
         $node->flags = 0; // Remove constant modifier
     }
-
-    /**
-     * {@inheritDoc}
-     */
-    public function needs(): string
-    {
-        return NameResolver::class;
-    }
 }
diff --git a/src/Target/Php71/ListKey.php b/src/Target/Php71/ListKey.php
index 353aea1..730a622 100644
--- a/src/Target/Php71/ListKey.php
+++ b/src/Target/Php71/ListKey.php
@@ -110,8 +110,8 @@ class ListKey extends Plugin
     /**
      * {@inheritDoc}
      */
-    public function needs(): string
+    public static function needs(): array
     {
-        return ArrayList::class;
+        return [ArrayList::class];
     }
 }
diff --git a/src/Target/Php71/MultipleCatchReplacer.php b/src/Target/Php71/MultipleCatchReplacer.php
index e5a4730..68ff85a 100644
--- a/src/Target/Php71/MultipleCatchReplacer.php
+++ b/src/Target/Php71/MultipleCatchReplacer.php
@@ -42,8 +42,8 @@ class MultipleCatchReplacer extends Plugin
      * 
      * @psalm-return class-string
      */
-    public function extends(): string
+    public static function extends(): string
     {
-        return ThrowableReplacer::class;
+        return [ThrowableReplacer::class];
     }
 }
diff --git a/src/Target/Php71/NullableTypeRemover.php b/src/Target/Php71/NullableTypeRemover.php
index a0705a2..bd06bea 100644
--- a/src/Target/Php71/NullableTypeRemover.php
+++ b/src/Target/Php71/NullableTypeRemover.php
@@ -12,7 +12,7 @@ class NullableTypeRemover extends Plugin
      *
      * @return array
      */
-    public function needs(): array
+    public static function needs(): array
     {
         return [
             TypeHintStripper::class => [
diff --git a/src/Traverser.php b/src/Traverser.php
index c5b6434..34b7854 100644
--- a/src/Traverser.php
+++ b/src/Traverser.php
@@ -4,5 +4,126 @@ namespace Phabel;
 
 class Traverser
 {
-    
-}
\ No newline at end of file
+    /**
+     * Plugins by level.
+     *
+     * @var array<int, array<class-string<PluginInterface>, array>>
+     */
+    private array $plugins = [];
+    /**
+     * Excluded plugins by level.
+     *
+     * @var array<int, array<class-string<PluginInterface>, bool>>
+     */
+    private array $excludedPlugins = [];
+    /**
+     * Files indexed by level.
+     *
+     * @var array<int, string[]>
+     */
+    private array $files = [];
+    /**
+     * Add plugin at a certain dependency level.
+     *
+     * @param class-string<PluginInterface> $plugin Plugin to add
+     * @param array                         $config Plugin configuration
+     * @param integer                       $level  Dependency level
+     *
+     * @return void
+     */
+    public function addPlugin(string $plugin, array $config, int $level): void
+    {
+        $this->plugins[$level][$plugin] = $config;
+    }
+    /**
+     * Exclude plugin at a certain dependency level.
+     *
+     * @param class-string<PluginInterface> $plugin            Plugin to exclude
+     * @param bool                          $excludeNextLevels Whether to exclude plugin from next levels, too
+     * @param integer                       $level             Dependency level
+     *
+     * @return void
+     */
+    public function excludePlugin(string $plugin, bool $excludeNextLevels, int $level): void
+    {
+        $this->excludedPlugins[$level][$plugin] = $excludeNextLevels;
+    }
+
+    /**
+     * Add file.
+     *
+     * @param string $path
+     * @param integer $level
+     * @return void
+     */
+    public function addFile(string $path, int $level): void
+    {
+        if (\in_array($path, $this->files[$level])) {
+            return;
+        }
+        $this->files[$level][] = $path;
+    }
+
+    /**
+     * Start traversing files.
+     *
+     * @return void
+     */
+    public function traverse(): void
+    {
+    }
+
+    private function resolveCycle(string $class, bool $need, array &$stack): void
+    {
+        
+        $allPlugins = [];
+        foreach ($this->plugins as $level => $plugins) {
+            foreach ($plugins as $plugin => $config) {
+                $needs = self::simpleNeeds($plugin);
+                foreach ($needs as $class => $config) {
+                    if ()
+                }
+            }
+        }
+    }
+
+    /**
+     * Simplify need requirements
+     *
+     * @param class-string<PluginInterface> $class Class to resolve
+     * 
+     * @return array<class-string<PluginInterface>, array>
+     */
+    private static function simpleNeeds(string $class): array
+    {
+        /**
+         * @var array<class-string<PluginInterface>, array>[]
+         */
+        static $cache = [];
+        if (isset($cache[$class])) {
+            return $cache[$class];
+        }
+        $needs = $class::needs();
+        return $cache[$class] = isset($needs[0]) ? array_fill_keys($needs, []) : $needs
+    }
+
+    /**
+     * Simplify extend requirements
+     *
+     * @param class-string<PluginInterface> $class Class to resolve
+     * 
+     * @return array<class-string<PluginInterface>, array>
+     */
+    private static function simpleExtends(string $class): array
+    {
+        /**
+         * @var array<class-string<PluginInterface>, array>[]
+         */
+        static $cache = [];
+        if (isset($cache[$class])) {
+            return $cache[$class];
+        }
+        $needs = $class::extends();
+        return $cache[$class] = isset($needs[0]) ? array_fill_keys($needs, []) : $needs
+    }
+}
diff --git a/src/TraverserConfig.php b/src/TraverserConfig.php
new file mode 100644
index 0000000..3093442
--- /dev/null
+++ b/src/TraverserConfig.php
@@ -0,0 +1,99 @@
+<?php
+
+namespace Phabel;
+
+class TraverserConfig
+{
+    /**
+     * Plugin configurations, indexed by level.
+     *
+     * @var array<int, array<class-string<PluginInterface>, array<0: bool, 1: array>[]>>
+     */
+    private array $plugins = [];
+    /**
+     * Excluded plugins by level.
+     *
+     * @var array<int, array<class-string<PluginInterface>, array[]>>
+     */
+    private array $excludedPlugins = [];
+    /**
+     * Files indexed by level.
+     *
+     * @var array<int, string[]>
+     */
+    private array $files = [];
+    /**
+     * Add plugin at a certain dependency level.
+     *
+     * @param class-string<PluginInterface> $plugin Plugin to add
+     * @param array                         $config Plugin configuration
+     * @param integer                       $level  Dependency level
+     *
+     * @return void
+     */
+    public function addPlugin(string $plugin, array $config, int $level): void
+    {
+        $this->plugins[$level][$plugin] []= $config;
+    }
+    /**
+     * Get all plugins at a certain level.
+     *
+     * @param integer $level Level
+     *
+     * @return array
+     */
+    public function getPlugins(int $level): array
+    {
+        return $this->plugins[$level];
+    }
+    /**
+     * Exclude plugin at a certain dependency level.
+     *
+     * @param class-string<PluginInterface> $plugin            Plugin to exclude
+     * @param bool                          $excludeNextLevels Whether to exclude plugin from next levels, too
+     * @param integer                       $level             Dependency level
+     *
+     * @return void
+     */
+    public function excludePlugin(string $plugin, bool $excludeNextLevels, int $level): void
+    {
+        $this->excludedPlugins[$level][$plugin][] = $excludeNextLevels;
+    }
+
+    /**
+     * Get final plugin array.
+     *
+     * @return array<int, array<class-string<PluginInterface, array>>>
+     */
+    public function final(): array
+    {
+        \ksort($this->plugins);
+        \ksort($this->excludedPlugins);
+        return [];
+    }
+
+    /**
+     * Trickle plugins down the dependency tree.
+     *
+     * @return void Insert 1% joke
+     */
+    private function trickleDown(): void
+    {
+        $met = [];
+        $maxLevel = \array_key_last($this->plugins);
+        foreach ($this->plugins as $level => $plugins) {
+            foreach ($plugins as $plugin => $config) {
+                $found = false;
+                for ($checkLevel = $level + 1; $checkLevel <= $maxLevel; $checkLevel++) {
+                    if (isset($this->plugins[$checkLevel][$plugin])
+                        && $this->plugins[$checkLevel][$plugin] !== $config) {
+                        $found = true;
+                        break;
+                    }
+                    $this->plugins[$checkLevel][$plugin] = $config;
+                }
+                $checkLevel--;
+            }
+        }
+    }
+}