defer imports + angular2 transformers

a.dart

library a;

import 'loader.dart';

// Normal code dependencies we discover automatically.
import 'b.dart';
import 'c.dart' deferred as c;

foo() {
  // Instead of c.loadLibrary() we do:
  load(#a.c, c.loadLibrary).then((_) {
    // here c is loaded and initialized!
  });
}

@Injectable() class A {}

a.ng_deps.dart

library a.ng_deps;

import 'loader.dart';
import 'a.dart';

import 'b.ng_deps.dart' as b;
import 'c.ng_deps.dart' deferred as c;

initReflector() {
  // do a's initialization
  registerReflectiveType(A, ...);

  // initialize sync dependencies
  b.initReflector();

  // register initialization for deferred dependencies (to be run when `a` loads them).
  register(#a.c, () => c.loadLibrary().then((_) => c.initReflector()));
}

c.ng_deps.dart

import 'c.dart'; // normal import is ok, all imports to c.ng_deps.dart are deferred

initReflector() {
  registerReflectiveType(C, ...);
}

loader.dart

import 'dart:async';

var _registry = {};

// adds something to run when loading `key`
register(key, Future f()) => _registry.putIfAbsent(key, () => []).add(f);

// run `f` to load what's registered under `key`, and then run everything
// that was registered under it:
load(key, loadLibrary) => loadLibrary()
    .then((_) => Future.forEach(_registry[key], (f) => f()));