Adds a vfs project

test/custom-worker.js

@@ -1,4 +1,19 @@
-self.customTSWorkerFactory = (TypeScriptWorker) => {
+// This example uses @typescript/vfs to create a virtual TS program
+// which can do work on a bg thread.
+
+importScripts("https://unpkg.com/@typescript/vfs@1.3.0/dist/vfs.globals.js")
+
+/**
+ *
+ * @param {import("../src/tsWorker").TypeScriptWorker} TypeScriptWorker
+ * @param {import("typescript")} ts
+ * @param {Record<string, string>} libFileMap
+ *
+ */
+const worker = (TypeScriptWorker, ts, libFileMap) => {
+  /** @type { import("@typescript/vfs") } */
+  const tsvfs = globalThis.tsvfs
+
   return class MonacoTSWorker extends TypeScriptWorker {
 
     // Adds a custom function to the webworker
@@ -8,5 +23,44 @@ self.customTSWorkerFactory = (TypeScriptWorker) => {
       return (firstDTS && firstDTS.text) || ""
     }
 
+    async printAST(fileName) {
+      console.log("Creating virtual TS project")
+      const compilerOptions = this.getCompilationSettings()
+      const fsMap = new Map()
+      for (const key of Object.keys(libFileMap)) {
+        fsMap.set(key, "/" + libFileMap[key])
+      }
+
+      const thisCode =  await this.getScriptText(fileName)
+      fsMap.set("index.ts", thisCode)
+
+      console.log("Starting up TS program")
+      const system = tsvfs.createSystem(fsMap)
+      const host = tsvfs.createVirtualCompilerHost(system, compilerOptions, ts)
+
+      const program = ts.createProgram({
+        rootNames: [...fsMap.keys()],
+        options: compilerOptions,
+        host: host.compilerHost,
+      })
+
+      // Now I can look at the AST for the .ts file too
+      const mainSrcFile = program.getSourceFile("index.ts")
+      let miniAST = "SourceFile"
+
+      const recurse = (parent, depth) => {
+        if (depth > 5) return
+        ts.forEachChild(parent, node => {
+          const spaces = "  ".repeat(depth + 1)
+          miniAST += `\n${spaces}${ts.SyntaxKind[node.kind]}`
+          recurse(node, depth + 1)
+        })
+      }
+      recurse(mainSrcFile, 0)
+      return miniAST
+    }
+
   }
 }
+
+self.customTSWorkerFactory = worker