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Initial demangler implementation, i.e. for use with TypeScript definitions
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‎lib/demangle/README.md‎

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![AS](https://avatars1.githubusercontent.com/u/28916798?s=48) demangle
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======================
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Demangles AssemblyScript module exports to a friendly object structure compatible with WebIDL and TypeScript definitions.
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Usage
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-----
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```js
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var module = require("@assemblyscript/demangle")(myWasmModule.instance.exports);
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// use module as defined in the .d.ts
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```
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Converting a memory offset (`this` value) to a class instance, i.e. where a class instance is returned by a WebAssembly function:
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```js
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var thisValue = wasmFunctionReturningAClassInstance();
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var myClass = MyClass.wrap(thisValue);
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```
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Converting a class instance to a memory offset (`this` value), i.e. where calling a WebAssembly function that expects a class instance:
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```js
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var thisValue = myClass.this;
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wasmFunctionExpectingAClassInstance(thisValue);
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```
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How does it work?
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-----------------
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AssemblyScript modules expose their exported elements by their internal name, which is a JSDoc-style fully qualified name indicating layers of nesting, and this module is able to recreate the original object structure from those names.
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* A `.` seperates a parent from a static child
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* A `#` separates a parent from an instance child
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* The `get:` prefix indicates a getter
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* The `set:` prefix indicates a setter
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Note that the compiler generates implicit getters and setters for instance fields for convenience. Support for instance members is achieved by generating wrappers that prepend the `this` value (offset of the instance in memory returned by the constructor) as the first argument when calling an instance method, getter or setter.

‎lib/demangle/index.js‎

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/**
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* @file AssemblyScript demangler.
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*/
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module.exports = demangle;
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/**
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* Demangles module exports to a friendly object structure compatible with WebIDL and TypeScript
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* definitions.
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*/
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/** Demangles AssemblyScript module exports to a friendly object structure. */
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function demangle(exports) {
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var root = {};
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for (let i in exports) {
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if (exports.hasOwnProperty(i)) {
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// TODO
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for (let internalName in exports) {
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if (!exports.hasOwnProperty(internalName)) continue;
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let elem = exports[internalName];
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let parts = internalName.split(".");
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let curr = root;
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while (parts.length > 1) {
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let part = parts.shift();
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if (!curr.hasOwnProperty(part)) curr[part] = {};
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curr = curr[part];
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}
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let name = parts[0];
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let hash = name.indexOf("#");
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if (hash >= 0) {
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let className = name.substring(0, hash);
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let classElem = curr[className];
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if (typeof classElem === "undefined" || !classElem.prototype) {
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let ctor = function(...args) {
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return ctor.wrap(ctor.prototype.constructor(...args));
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};
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ctor.prototype = {};
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ctor.wrap = function(thisValue) {
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return Object.create(ctor.prototype, { "this": { value: thisValue, writable: false } });
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};
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if (classElem) Object.getOwnPropertyNames(classElem).forEach(name =>
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Object.defineProperty(ctor, name, Object.getOwnPropertyDescriptor(classElem, name))
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);
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curr[className] = ctor;
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}
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name = name.substring(hash + 1);
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curr = curr[className].prototype;
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if (/^(get|set):/.test(name)) {
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if (!curr.hasOwnProperty(name = name.substring(4))) {
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let getter = exports[internalName.replace("set:", "get:")];
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let setter = exports[internalName.replace("get:", "set:")];
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Object.defineProperty(curr, name, {
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get: function() { return getter(this.this); },
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set: function(value) { setter(this.this, value); }
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});
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}
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} else curr[name] = function(...args) { return elem(this.this, ...args); };
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} else {
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if (/^(get|set):/.test(name)) {
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if (!curr.hasOwnProperty(name = name.substring(4))) {
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Object.defineProperty(curr, name, {
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get: exports[internalName.replace("set:", "get:")],
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set: exports[internalName.replace("get:", "set:")]
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});
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}
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} else curr[name] = elem;
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}
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}
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return root;

‎lib/demangle/package.json‎

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{
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"name": "@assemblyscript/demangle",
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"version": "1.0.0",
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"main": "index.js",
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"scripts": {
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"test": "node tests"
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},
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"files": [
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"index.js",
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"package.json",
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"README.md"
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]
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}

‎lib/demangle/tests/index.js‎

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var assert = require("assert");
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var inspect = require("util").inspect;
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var demangle = require("..");
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var __this = 8;
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var __usualDoors = 3;
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var __doors = -1;
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var exports = demangle({
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"vroom": function() { console.log("vroom", arguments); },
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"Car.MAX_DOORS": 5,
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"Car.get:usualDoors": function() { console.log("Car#get:usualDoors", arguments); return __usualDoors; },
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"Car.set:usualDoors": function(value) { console.log("Car#set:usualDoors", arguments); __usualDoors = value; },
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"Car#constructor": function(this_, doors) { console.log("Car#constructor", arguments); __doors = doors; return __this; },
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"Car#openDoors": function(this_) { console.log("Car#openDoors", arguments); return true; },
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"Car#get:doors": function(this_) { console.log("Car#get:doors", arguments); return __doors; },
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"Car#set:doors": function(this_, value) { console.log("Car#set:doors", arguments); __doors = value; }
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});
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console.log(inspect(exports, true));
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exports.vroom(1, 2, 3);
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var Car = exports.Car;
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assert(Car.usualDoors == 3);
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exports.Car.usualDoors = exports.Car.usualDoors + 2;
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assert(Car.usualDoors == 5);
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var car = new exports.Car(2);
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assert(car.this == 8);
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assert(car.openDoors() == true);
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assert(car.doors == 2);
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car.doors = car.doors + 2;
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assert(car.doors == 4);
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console.log(inspect(car, true));
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var wrappedCar = exports.Car.wrap(16);
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assert(wrappedCar.this == 16);
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console.log(inspect(wrappedCar, true));

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