Adds MetalCompilerPluginSupport with useful bundle extension to help …

Package.swift

@@ -8,13 +8,17 @@ let package = Package(
         .plugin(
             name: "MetalCompilerPlugin",
             targets: ["MetalCompilerPlugin"]
-        )
+        ),
+        .library(name: "MetalCompilerPluginSupport", targets: ["MetalCompilerPluginSupport"]),
     ],
     targets: [
         .plugin(
             name: "MetalCompilerPlugin",
             capability: .buildTool()
         ),
+        .target(
+            name: "MetalCompilerPluginSupport"
+        ),
 
         // The following targets are for testing the plugin and are examples of its usage.
         .target(

Sources/MetalCompilerPluginSupport/MetalCompilerPluginSupport.swift

@@ -0,0 +1,37 @@
+import Foundation
+
+public extension Bundle {
+    var parentBundle: Bundle? {
+        let components = bundlePath.split(separator: "/")
+        guard let index = components.dropLast().firstIndex(where: { $0.hasSuffix(".bundle") || $0.hasSuffix(".xctest") || $0.hasSuffix(".app") }) else {
+            return nil
+        }
+        let path = "/" + components[...index].joined(separator: "/")
+        return Bundle(path: path)
+    }
+
+    var childBundles: [Bundle] {
+        guard let resourcePath else {
+            return []
+        }
+        let fileManager = FileManager()
+        guard let paths = try? fileManager.contentsOfDirectory(atPath: resourcePath) else {
+            return []
+        }
+
+        return paths.filter {
+            $0.hasSuffix(".bundle")
+        }
+        .map {
+            Bundle(path: resourcePath.appending("/").appending($0))!
+        }
+    }
+
+    /// Looks for a child bundle with a name of the form: `"*_<suffix>.bundle"`. Use like `Bundle.module.parentBundle?.childBundle(withSuffix: "<target name>")` to help find a bundle with shaders
+    func childBundle(withSuffix suffix: String) -> Bundle? {
+        childBundles.first {
+            $0.bundleURL.lastPathComponent.hasSuffix(("_\(suffix).bundle"))
+        }
+    }
+}
+