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// Copyright (c) 2012, 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.
/**
* This library exports all of the commonly used functions and types for
* building UI's.
*
* See this article for more information:
* <http://www.dartlang.org/articles/dart-web-components/>.
*/
library polymer;
import 'dart:async';
import 'dart:mirrors';
import 'package:mdv/mdv.dart' as mdv;
import 'package:observe/src/microtask.dart';
import 'package:path/path.dart' as path;
import 'polymer_element.dart' show registerPolymerElement;
export 'package:custom_element/custom_element.dart';
export 'package:observe/observe.dart';
export 'package:observe/src/microtask.dart';
export 'observe.dart';
export 'observe_html.dart';
export 'polymer_element.dart';
export 'safe_html.dart';
/** Annotation used to automatically register polymer elements. */
class CustomTag {
final String tagName;
const CustomTag(this.tagName);
}
/**
* Metadata used to label static or top-level methods that are called
* automatically when loading the library of a custom element.
*/
const initMethod = const _InitMethodAnnotation();
/**
* Initializes a polymer application as follows:
* * set up up polling for observable changes
* * initialize MDV
* * for each library in [libraries], register custom elements labeled with
* [CustomTag] and invoke the initialization method on it.
*
* The initialization on each library is either a method named `main` or
* a top-level function and annotated with [initMethod].
*
* The urls in [libraries] can be absolute or relative to [srcUrl].
*/
void initPolymer(List<String> libraries, [String srcUrl]) {
wrapMicrotask(() {
// DOM events don't yet go through microtasks, so we catch those here.
new Timer.periodic(new Duration(milliseconds: 125),
(_) => performMicrotaskCheckpoint());
// TODO(jmesserly): mdv should use initMdv instead of mdv.initialize.
mdv.initialize();
for (var lib in libraries) {
_loadLibrary(lib, srcUrl);
}
})();
}
/** All libraries in the current isolate. */
final _libs = currentMirrorSystem().libraries;
/**
* Reads the library at [uriString] (which can be an absolute URI or a relative
* URI from [srcUrl]), and:
*
* * If present, invokes `main`.
*
* * If present, invokes any top-level and static functions marked
* with the [initMethod] annotation (in the order they appear).
*
* * Registers any [PolymerElement] that is marked with the [CustomTag]
* annotation.
*/
void _loadLibrary(String uriString, [String srcUrl]) {
var uri = Uri.parse(uriString);
if (uri.scheme == '' && srcUrl != null) {
uri = Uri.parse(path.normalize(path.join(path.dirname(srcUrl), uriString)));
}
var lib = _libs[uri];
if (lib == null) {
print('warning: $uri library not found');
return;
}
// Invoke `main`, if present.
if (lib.functions[const Symbol('main')] != null) {
lib.invoke(const Symbol('main'), const []);
}
// Search top-level functions marked with @initMethod
for (var f in lib.functions.values) {
_maybeInvoke(lib, f);
}
for (var c in lib.classes.values) {
// Search for @CustomTag on classes
for (var m in c.metadata) {
var meta = m.reflectee;
if (meta is CustomTag) {
registerPolymerElement(meta.tagName,
() => c.newInstance(const Symbol(''), const []).reflectee);
}
}
// TODO(sigmund): check also static methods marked with @initMethod.
// This is blocked on two bugs:
// - dartbug.com/12133 (static methods are incorrectly listed as top-level
// in dart2js, so they end up being called twice)
// - dartbug.com/12134 (sometimes "method.metadata" throws an exception,
// we could wrap and hide those exceptions, but it's not ideal).
}
}
void _maybeInvoke(ObjectMirror obj, MethodMirror method) {
var annotationFound = false;
for (var meta in method.metadata) {
if (identical(meta.reflectee, initMethod)) {
annotationFound = true;
break;
}
}
if (!annotationFound) return;
if (!method.isStatic) {
print("warning: methods marked with @initMethod should be static,"
" ${method.simpleName} is not.");
return;
}
if (!method.parameters.where((p) => !p.isOptional).isEmpty) {
print("warning: methods marked with @initMethod should take no "
"arguments, ${method.simpleName} expects some.");
return;
}
obj.invoke(method.simpleName, const []);
}
class _InitMethodAnnotation {
const _InitMethodAnnotation();
}