Use transform classes

Author: dcodeIO

cli/asc.js

@@ -212,15 +212,27 @@ exports.main = function main(argv, options, callback) {
   // Set up transforms
   const transforms = [];
   if (args.transform) {
-    args.transform.forEach(transform =>
-      transforms.push(
-        require(
-          path.isAbsolute(transform = transform.trim())
-            ? transform
-            : path.join(process.cwd(), transform)
-        )
-      )
-    );
+    class Transform {
+      baseDir = baseDir;
+      writeFile = writeFile;
+      readFile = readFile;
+      listFiles = listFiles;
+    }
+    args.transform.forEach(filename => {
+      const ctor = require(
+        path.isAbsolute(filename = filename.trim())
+          ? filename
+          : path.join(process.cwd(), filename)
+      );
+      let impl;
+      if (typeof ctor === "function") {
+        Object.setPrototypeOf(ctor, Transform);
+        impl = new ctor();
+      } else {
+        impl = ctor; // legacy module
+      }
+      transforms.push(impl);
+    });
   }
   function applyTransform(name, ...args) {
     transforms.forEach(transform => {

cli/transform.d.ts

@@ -3,9 +3,22 @@
  * @module cli/transform
  *//***/
 
-import { Parser } from "../src/parser";
+import { Parser } from "..";
+
+export abstract class Transform {
+
+  /** Base directory. */
+  readonly baseDir: string;
+
+  /** Writes a file to disk. */
+  writeFile(filename: string, contents: string | Uint8Array, baseDir: string): boolean;
+
+  /** Reads a file from disk. */
+  readFile(filename: string, baseDir: string): string | null;
+
+  /** Lists all files in a directory. */
+  listFiles(dirname: string, baseDir: string): string[] | null;
 
-export interface Transform {
   /** Called when parsing is complete, before a program is instantiated from the AST. */
-  afterParse(parser: Parser): void;
+  afterParse?(parser: Parser): void;
 }

cli/transform.js

@@ -0,0 +1,5 @@
+class Transform {
+  // becomes replaced with the actual base by asc
+}
+
+exports.Transform = Transform;

examples/transform/assembly/index.ts

@@ -0,0 +1 @@
+// empty

examples/transform/mytransform.js

@@ -0,0 +1,12 @@
+const { Transform } = require("../../cli/transform"); // "assemblyscript/cli/transform"
+const { SourceKind } = require("../.."); // "assemblyscript"
+
+class MyTransform extends Transform {
+  afterParse(parser) {
+    console.error("afterParse called, baseDir = " + this.baseDir);
+    var sources = parser.program.sources;
+    sources.forEach(source => console.error("  " + source.internalPath + " [" + SourceKind[source.sourceKind] + "]"));
+  }
+}
+
+module.exports = MyTransform;

examples/transform/package.json

@@ -0,0 +1,5 @@
+{
+  "scripts": {
+    "test": "asc assembly/index.ts --runtime none --transform mytransform.js"
+  }
+}