Add transform example

Author: dcodeIO

README.md

@@ -52,4 +52,7 @@ General examples showing how to utilize specific AssemblyScript features.
 * [Browser SDK](./sdk)<br />
   Shows how to use the browser SDK to run the AssemblyScript compiler in the browser.
 
-  <img src="./sdk/preview.jpg" />
+  <img src="./sdk/preview.jpg" />
+
+* [Compiler transforms](./transform)<br />
+  An example of using compiler transforms to hook into the compilation process.

loader/assembly/index.ts

@@ -46,8 +46,8 @@ export function getMyArray(size: i32): Int32Array {
 
 // Example 5: Passing an array from JavaScript to WebAssembly.
 
-// Likewise, we can also allocate an array on the JavaScript side and pass it
-// its pointer to WebAssembly, then doing something with it.
+// Likewise, we can also allocate an array on the JavaScript side and pass its
+// pointer to WebAssembly, then doing something with it.
 
 // see: tests/index.js "Test for Example 5"
 

loader/tests/index.js

@@ -121,29 +121,48 @@ const {
     player = new myModule.Game.Player(namePtr);
     __release(namePtr);
   }
-  console.log("  Player (new): " + __getString(player.toString()));
+
+  // Let's see how our player looks now by calling toString
+  {
+    const strPtr = player.toString();
+    console.log("  Player (new): " + __getString(strPtr));
+    __release(strPtr);
+  }
 
   // Move them and log again
-  player.move(10, 20);
-  console.log("  Player (moved): " + __getString(player.toString()));
+  {
+    player.move(10, 20);
+    const strPtr = player.toString();
+    console.log("  Player (moved): " + __getString(strPtr));
+    __release(strPtr);
+  }
 
   // Obtaining just the position. Note that we can `wrap` any pointer with
-  // the matching class within the object structure made by the loader.
+  // the matching class within the object structure made by the loader, and
+  // that a position's x and y properties are just basic values, not objects,
+  // so tracking references does not apply to them.
   {
-    const positionPtr = player.position; // calls a getter (implicit `return`)
+    const positionPtr = player.position; // implicit getter, retained for us
     const position = myModule.Game.Position.wrap(positionPtr);
     console.log("  Position (wrapped): " + position.x + "/" + position.y);
 
     position.x -= 100;
     position.y += 200;
-    console.log("  Position (moved): " + __getString(position.toString()));
 
-    __release(positionPtr); // we are done with the returned object
+    const strPtr = position.toString();
+    console.log("  Position (moved): " + __getString(strPtr));
+    __release(strPtr);
+
+    __release(positionPtr);
   }
 
   // Finish 'em
-  player.kill();
-  console.log("  Player (finished): " + __getString(player.toString()));
+  {
+    player.kill();
+    const strPtr = player.toString();
+    console.log("  Player (finished): " + __getString(strPtr));
+    __release(strPtr); // we are done with the returned object
+  }
 
   __release(player); // a tidy house, a tidy mind.
 }

transform/README.md

@@ -0,0 +1,24 @@
+Compiler transforms
+===================
+
+An [AssemblyScript](http://assemblyscript.org) example of using compiler transforms to hook into the compilation process.
+
+Instructions
+------------
+
+* [JavaScript transform](./mytransform.js)<br />
+  An ES6 JavaScript transform. Recommended.
+
+* [TypeScript transform](./mytransform.ts)<br />
+  A transform written in TypeScript. This works currently because the compiler
+  utilizes ts-node anyway, so can as well transpile the transform to ES6.
+
+See [package.json](./package.json) on how to utilize the transforms with `asc`.
+You may also run
+
+```
+$> npm install
+$> npm test
+```
+
+to verify that it works.

transform/assembly/index.ts

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

transform/mytransform.js

@@ -0,0 +1,23 @@
+const { Transform } = require("assemblyscript/cli/transform");
+const { SourceKind, ElementKind } = require("assemblyscript");
+const binaryen = require("binaryen");
+
+class MyTransform extends Transform {
+  afterParse(parser) {
+    this.log("[mytransform.js] afterParse called, baseDir = " + this.baseDir);
+    var sources = parser.program.sources;
+    sources.forEach(source => this.log("  " + source.internalPath + " [" + SourceKind[source.sourceKind] + "]"));
+  }
+  afterInitialize(program) {
+    this.log("[mytransform.js] afterInitialize called");
+    var elements = program.elementsByName;
+    elements.forEach(element => this.log("  " + element.internalName + " [" + ElementKind[element.kind] + "]"));
+  }
+  afterCompile(asModule) {
+    this.log("[mytransform.js] afterCompile called");
+    var module = binaryen.wrapModule(asModule.ref);
+    this.log(module.emitBinary());
+  }
+}
+
+module.exports = MyTransform;

transform/mytransform.ts

@@ -0,0 +1,25 @@
+import { Transform } from "assemblyscript/cli/transform";
+import { Parser, Module, SourceKind, ElementKind, Program } from "assemblyscript";
+import * as binaryen from "binaryen";
+
+class MyTransform extends Transform {
+  afterParse(parser: Parser): void {
+    this.log("[mytransform.ts] afterParse called, baseDir = " + this.baseDir);
+    var sources = parser.program.sources;
+    sources.forEach(source => this.log("  " + source.internalPath + " [" + SourceKind[source.sourceKind] + "]"));
+  }
+  afterInitialize(program: Program) {
+    this.log("[mytransform.ts] afterInitialize called");
+    var elements = program.elementsByName;
+    elements.forEach(element => this.log("  " + element.internalName + " [" + ElementKind[element.kind] + "]"));
+  }
+  afterCompile(asModule: Module): void {
+    this.log("[mytransform.ts] afterCompile called");
+    var module = binaryen.wrapModule(asModule.ref);
+    this.log(module.emitBinary());
+  }
+}
+
+console.log()
+
+export = MyTransform;

transform/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "@assemblyscript/transform-example",
+  "version": "1.0.0",
+  "private": true,
+  "scripts": {
+    "test:js": "asc assembly/index.ts --runtime none --transform ./mytransform.js",
+    "test:ts": "asc assembly/index.ts --runtime none --transform ./mytransform.ts",
+    "test:multi": "asc assembly/index.ts --runtime none --transform ./mytransform.js --transform ./mytransform.ts",
+    "test": "npm run test:js && npm run test:ts && npm run test:multi"
+  },
+  "devDependencies": {
+    "assemblyscript": "latest",
+    "ts-node": "^8.10.1",
+    "typescript": "^3.8.3"
+  }
+}