Improve source file detection and tests

- Use SwiftPM-provided sourceFiles for filtering - Add Utils.swift with
URL descendant check - Update example to use Views/ instead of Folder/ -
Add test for non-included Swift file - Update .zed settings to disable
VSCode CSS language server

.zed/settings.json

@@ -0,0 +1,11 @@
+// Folder-specific settings
+//
+// For a full list of overridable settings, and general information on folder-specific settings,
+// see the documentation: https://zed.dev/docs/configuring-zed#settings-files
+{
+  "languages": {
+    "CSS": {
+      "language_servers": ["!vscode-css-language-server"]
+    }
+  }
+}

Plugins/TailwindCSS/TailwindCSSBuildPlugin.swift

@@ -48,6 +48,10 @@ struct TailwindCSSBuildPlugin: BuildToolPlugin {
     context: PluginContext,
     target: Target
   ) throws -> [Command] {
+    guard let sourceFileURLs = target.sourceModule?.sourceFiles.map({ $0.url }) else {
+      throw BuildError.notASourceModule
+    }
+
     let tailwindCSSURL: URL = target.directoryURL.appending(component: "Tailwind.css")
     guard let cssContent = try? String(contentsOf: tailwindCSSURL) else {
       throw BuildError.missingTailwindCSSFile
@@ -60,18 +64,25 @@ struct TailwindCSSBuildPlugin: BuildToolPlugin {
       throw BuildError.sourceNotDeclarationUnsupported
     }
 
-    let sourcePaths =
+    let sourcePatterns =
       cssContent
       .matches(of: sourceDeclarationRegex)
       .compactMap { String($0.output.1) }
-    let sourceURLs: [URL] = sourcePaths.map { path in
-      // Simplified handling: If ** is used, we just include everything in the directory.
+    let sourcePatternURLs: [URL] = sourcePatterns.map { path in
+      // Simplified handling: If `**` is used, we just include everything in the directory.
+      // It's unlikely we will have the same glob processing logic as Tailwind CSS CLI,
+      // so we may as well just expand the coverage.
+      // This only affects SwiftPM change detection: Tailwind CSS CLI will handle the globbing correctly.
       let globlessPath = path.replacing(/\*\*.*/, with: "")
       return target.directoryURL
         .appending(component: globlessPath, directoryHint: .inferFromPath)
         .resolvingSymlinksInPath()
     }
 
+    let includedSourceURLs = sourceFileURLs.filter { file in
+      sourcePatternURLs.contains { file.isOrIsDescendant(of: $0) }
+    }
+
     let tailwindCLIURL: URL = try context.tool(named: "tailwindcss").url
     let outputBundleURL = context.pluginWorkDirectoryURL
       .appending(component: outputBundleName, directoryHint: .isDirectory)
@@ -79,9 +90,10 @@ struct TailwindCSSBuildPlugin: BuildToolPlugin {
       component: outputCSSFilename, directoryHint: .notDirectory)
 
     print("Tailwind CSS Build Plugin")
-    print("Tailwind CSS File: \(tailwindCSSURL.path)")
-    print("@source declarations: \(sourcePaths)")
-    print("Source files: \(sourceURLs.map(\.path))")
+    print("Tailwind.css: \(tailwindCSSURL.path)")
+    print("@source declarations: \(sourcePatterns)")
+    print("All source files: \(sourceFileURLs.map(\.path))")
+    print("Input files: \(includedSourceURLs.map(\.path))")
     print("Output: \(outputURL.path)")
 
     return [
@@ -93,7 +105,7 @@ struct TailwindCSSBuildPlugin: BuildToolPlugin {
           "--output", outputURL.path,
           "--minify",
         ],
-        inputFiles: [tailwindCSSURL] + sourceURLs,
+        inputFiles: [tailwindCSSURL] + includedSourceURLs,
         outputFiles: [outputBundleURL]
       )
     ]
@@ -102,12 +114,15 @@ struct TailwindCSSBuildPlugin: BuildToolPlugin {
 
 extension TailwindCSSBuildPlugin {
   enum BuildError: Error {
+    case notASourceModule
     case missingTailwindCSSFile
     case missingImportStatement
     case sourceNotDeclarationUnsupported
 
     var localizedDescription: String {
       switch self {
+      case .notASourceModule:
+        "The target is not a source module."
       case .missingTailwindCSSFile:
         "Tailwind.css file not found in the target directory."
       case .missingImportStatement:

Plugins/TailwindCSS/Utils.swift

@@ -0,0 +1,24 @@
+import Foundation
+
+extension URL {
+  func isOrIsDescendant(of ancestor: URL) -> Bool {
+    guard ancestor.isFileURL, self.isFileURL else {
+      return false
+    }
+
+    let ancestorComponents = ancestor.pathComponents
+    let selfComponents = self.pathComponents
+
+    guard selfComponents.count >= ancestorComponents.count else {
+      return false
+    }
+
+    for (index, component) in ancestorComponents.enumerated() {
+      if selfComponents[index] != component {
+        return false
+      }
+    }
+
+    return true
+  }
+}

Sources/SwiftTailwindExample/NotIncluded.swift

@@ -0,0 +1,5 @@
+// This file is not included in Tailwind.css, so TW classes here will not be generated.
+let html =
+  """
+  <a href="swift.org" class="text-sm">Swift</a>
+  """

Sources/SwiftTailwindExample/Tailwind.css

@@ -4,5 +4,5 @@
 /** You must specify `source(none)` after `tailwindcss` import and add `@source` for each source file / folder you want to include. */
 @import "tailwindcss" source(none);
 @source "./Example.swift";
-@source "./Folder";
-@source "./Folder/**/*.swift";
+@source "./Views";
+@source "./Views/**/*.swift";

Tests/SwiftTailwindTests/Tests.swift

@@ -21,6 +21,10 @@ struct SwiftTailwindExampleTests {
       generatedCSS?.contains("bg-red-100") == true,
       "Arbitary value class used in Folder/Template.swift is generated."
     )
+    #expect(
+      generatedCSS?.contains("text-sm") == false,
+      "Class used in other non-included Swift code is not generated."
+    )
     #expect(
       generatedCSS?.contains("bg-blue-500") == false,
       "Class not used is not generated."