blob: 5f874f8858382435f2a4e483aa028b671f1b5637 [file] [log] [blame]
// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
/// Contains logic to initialize web_components apps during development. This
/// implementation uses dart:mirrors to load each library as they are discovered
/// through HTML imports. This is only meant to be used during development in
/// dartium, and the web_components transformers replace this implementation
/// for deployment.
library web_components.src.mirror_initializer;
import 'dart:async';
import 'dart:collection' show LinkedHashMap;
import 'dart:mirrors';
import 'dart:html';
import 'package:initialize/initialize.dart' as init;
const bool deployMode = false;
Future run({List<Type> typeFilter, init.InitializerFilter customFilter}) async {
var libraryUris = _discoverLibrariesToLoad(document, window.location.href)
for (var uri in libraryUris) {
typeFilter: typeFilter, customFilter: customFilter, from: uri);
return null;
/// Walks the HTML import structure to discover all script tags that are
/// implicitly loaded. This code is only used in Dartium and should only be
/// called after all HTML imports are resolved. Polymer ensures this by asking
/// users to put their Dart script tags after all HTML imports (this is checked
/// by the linter, and Dartium will otherwise show an error message).
Iterable<_ScriptInfo> _discoverScripts(
Document doc, String baseUri, [_State state]) {
if (state == null) state = new _State();
if (doc == null) {
print('warning: $baseUri not found.');
return state.scripts.values;
if (!state.seen.add(doc)) return state.scripts.values;
for (var node in doc.querySelectorAll('script,link[rel="import"]')) {
if (node is LinkElement) {
_discoverScripts(node.import, node.href, state);
} else if (node is ScriptElement && node.type == 'application/dart') {
var info = _scriptInfoFor(node, baseUri);
if (state.scripts.containsKey(info.resolvedUrl)) {
// TODO(jakemac): Move this to a web_components uri.
print('warning: Script `${info.resolvedUrl}` included more than once. '
'See for more details.');
} else {
state.scripts[info.resolvedUrl] = info;
return state.scripts.values;
/// Internal state used in [_discoverScripts].
class _State {
/// Documents that we have visited thus far.
final Set<Document> seen = new Set();
/// Scripts that have been discovered, in tree order.
final LinkedHashMap<String, _ScriptInfo> scripts = {};
/// Holds information about a Dart script tag.
class _ScriptInfo {
/// The original URL seen in the tag fully resolved.
final String resolvedUrl;
/// Whether it seems to be a 'package:' URL (starts with the package-root).
bool get isPackage => packageUrl != null;
/// The equivalent 'package:' URL, if any.
final String packageUrl;
_ScriptInfo(this.resolvedUrl, {this.packageUrl});
// TODO(sigmund): explore other (cheaper) ways to resolve URIs relative to the
// root library (see
final _rootUri = currentMirrorSystem().isolate.rootLibrary.uri;
/// Returns [_ScriptInfo] for [script] which was seen in [baseUri].
_ScriptInfo _scriptInfoFor(script, baseUri) {
var uriString = script.src;
if (uriString != '') {
var uri = _rootUri.resolve(uriString);
if (!_isHttpStylePackageUrl(uri)) return new _ScriptInfo('$uri');
// Use package: urls if available. This rule here is more permissive than
// how we translate urls in polymer-build, but we expect Dartium to limit
// the cases where there are differences. The polymer-build issues an error
// when using packages/ inside lib without properly stepping out all the way
// to the packages folder. If users don't create symlinks in the source
// tree, then Dartium will also complain because it won't find the file seen
// in an HTML import.
var packagePath = uri.path.substring(
uri.path.lastIndexOf('packages/') + 'packages/'.length);
return new _ScriptInfo('$uri', packageUrl: 'package:$packagePath');
// Even in the case of inline scripts its ok to just use the baseUri since
// there can only be one per page.
return new _ScriptInfo(baseUri);
/// Whether [uri] is an http URI that contains a 'packages' segment, and
/// therefore could be converted into a 'package:' URI.
bool _isHttpStylePackageUrl(Uri uri) {
var uriPath = uri.path;
return uri.scheme == _rootUri.scheme &&
// Don't process cross-domain uris.
uri.authority == _rootUri.authority &&
uriPath.endsWith('.dart') &&
(uriPath.contains('/packages/') || uriPath.startsWith('packages/'));
Iterable<String> _discoverLibrariesToLoad(Document doc, String baseUri) =>
_discoverScripts(doc, baseUri).map(
(info) => _packageUrlExists(info) ? info.packageUrl : info.resolvedUrl);
/// All libraries in the current isolate.
final _libs = currentMirrorSystem().libraries;
bool _packageUrlExists(_ScriptInfo info) =>
info.isPackage && _libs[Uri.parse(info.packageUrl)] != null;