add source(…) improvements to @tailwindcss/vite

Author: RobinMalfait

packages/@tailwindcss-vite/src/index.ts

@@ -35,7 +35,7 @@ export default function tailwindcss(): Plugin[] {
   // Note: To improve performance, we do not remove candidates from this set.
   // This means a longer-ongoing dev mode session might contain candidates that
   // are no longer referenced in code.
-  let moduleGraphCandidates = new Set<string>()
+  let moduleGraphCandidates = new DefaultMap<string, Set<string>>(() => new Set<string>())
   let moduleGraphScanner = new Scanner({})
 
   let roots: DefaultMap<string, Root> = new DefaultMap(
@@ -46,7 +46,7 @@ export default function tailwindcss(): Plugin[] {
     let updated = false
     for (let candidate of moduleGraphScanner.scanFiles([{ content, extension }])) {
       updated = true
-      moduleGraphCandidates.add(candidate)
+      moduleGraphCandidates.get(id).add(candidate)
     }
 
     if (updated) {
@@ -350,7 +350,7 @@ class Root {
 
   constructor(
     private id: string,
-    private getSharedCandidates: () => Set<string>,
+    private getSharedCandidates: () => Map<string, Set<string>>,
     private base: string,
   ) {}
 
@@ -379,9 +379,22 @@ class Root {
       })
       env.DEBUG && console.timeEnd('[@tailwindcss/vite] Setup compiler')
 
-      this.scanner = new Scanner({
-        sources: this.compiler.globs,
-      })
+      let sources = (() => {
+        // Disable auto source detection
+        if (this.compiler.root === 'none') {
+          return []
+        }
+
+        // No root specified, use the module graph
+        if (this.compiler.root === null) {
+          return []
+        }
+
+        // Use the specified root
+        return [this.compiler.root]
+      })().concat(this.compiler.globs)
+
+      this.scanner = new Scanner({ sources })
     }
 
     // This should not be here, but right now the Vite plugin is setup where we
@@ -416,9 +429,39 @@ class Root {
     this.requiresRebuild = true
 
     env.DEBUG && console.time('[@tailwindcss/vite] Build CSS')
-    let result = this.compiler.build([...this.getSharedCandidates(), ...this.candidates])
+    let result = this.compiler.build([...this.sharedCandidates(), ...this.candidates])
     env.DEBUG && console.timeEnd('[@tailwindcss/vite] Build CSS')
 
     return result
   }
+
+  private sharedCandidates(): Set<string> {
+    if (!this.compiler) return new Set()
+    if (this.compiler.root === 'none') return new Set()
+
+    let root = this.compiler.root
+    let basePath = root ? path.resolve(root.base, root.pattern) : null
+
+    function moduleIdIsAllowed(id: string) {
+      if (basePath === null) return true
+
+      // This a virtual module that's not on the file system
+      // TODO: What should we do here?
+      if (!id.startsWith('/')) return true
+
+      return id.startsWith(basePath)
+    }
+
+    let shared = new Set<string>()
+
+    for (let [id, candidates] of this.getSharedCandidates()) {
+      if (!moduleIdIsAllowed(id)) continue
+
+      for (let candidate of candidates) {
+        shared.add(candidate)
+      }
+    }
+
+    return shared
+  }
 }