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dam0vm3nt/ObservablePolymerNotifier.dart

Last active January 18, 2018 08:01
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Auto notify support for new polymer
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ObservablePolymerNotifier.dart
import "package:polymer/polymer.dart";
import "package:observe/observe.dart";
import "package:smoke/smoke.dart";
import "package:logging/logging.dart";
class ObservablePolymerNotifier {
static final Logger _logger = new Logger("polymer.auto.notify");
String _path="";
PolymerElement _element;
Observable _target;
StreamSubscription _sub;
Map<String,ObservablePolymerNotifier> _subNotifiers = {};
ObservablePolymerNotifier(PolymerElement element, var target,[String path=""]) {
_element = element;
_path = path;
_target = target;
if (target is Observable) {
_sub = target.changes.listen((List<ChangeRecord> recs) {
recs.where((ChangeRecord cr) => cr is PropertyChangeRecord).forEach((PropertyChangeRecord pcr) {
var val = pcr.newValue;
_notifySymbol(symbolToName(pcr.name), val);
});
});
} else if (target is ObservableList) {
_sub = (target as ObservableList).listChanges.listen((List<ListChangeRecord> rc){
// Notify splice
rc.forEach((ListChangeRecord lc) {
_notifySplice(target,"${_path}${symbolToName(pcr.name)}",lc.index,lc.addedCount,lc.removed);
// Fix observers
if(lc.removed!=null) {
for(int i=0;i<lc.removed.length;i++) {
_subNotifiers.remove((lc.index+i).toString()).close();
}
// fix path on the rest
for (int i=lc.index;i<target.length;i++) {
_subNotifiers[i.toString()]=_subNotifiers.remove((i+lc.removed.length).toString())
.._path="${_path}${symbolToName(pcr.name)}.${i}";
}
}
if (lc.addedCount>0) {
// Fix path on tail
for (int i=lc.index+lc.addedCount;i<target.length;i++) {
_subNotifiers[i.toString()] =_subNotifiers.remove((i-lc.addedCount).toString())
.._path="${_path}${symbolToName(pcr.name)}.${i}";
}
// Add new observers
for (int i=lc.index;i<lc.addedCount+lc.index;i++) {
_notifySymbol(i.toString(),target[i]);
}
}
});
});
}
// Add Sub
if (target is List) {
for (int i=0;i<target.length;i++) {
_notifySplice(target,"${_path}".substring(0,_path.length-1),0,target.length,[]);
_notifySymbol(i.toString(),target[i]);
}
} else {
List<Declaration> fields = query(target.runtimeType,new QueryOptions(includeFields:true,includeProperties:true,includeInherited:false));
fields.forEach((Declaration f) {
if (f.annotations.any((a)=> a is ObservableProperty)) {
var fieldValue=read(target,f.name);
_notifySymbol(symbolToName(f.name),fieldValue);
}
});
}
}
void _notifySymbol(String name,var value) {
String path = "${_path}${name}";
_logger.fine("Notify ${path} with ${value} for ${_element}");
_element.notifyPath(path,value);
_installSubNotifier(name,value);
}
void _installSubNotifier(String name,var target) {
// Attach a new sub notifier for observable objects
_logger.fine("Installing subnotifier for ${name} with ${target}");
ObservablePolymerNotifier subNotifier = _subNotifiers[name];
if (subNotifier!=null) {
subNotifier.close();
}
String subPath = "${_path}${name}";
if (target!=null && (target is Observable || target is List)) {
subNotifier = new ObservablePolymerNotifier(_element,target,"${subPath}.");
_subNotifiers[name] = subNotifier;
}
}
void close() {
_subNotifiers.values.forEach((ObservablePolymerNotifier x) => x.close());
_subNotifiers.clear();
if (_sub!=null) {
_sub.cancel();
_sub=null;
}
}
void _notifySplice(List array, String path, int index, int added, List removed) =>
_element.jsElement.callMethod('_notifySplice', [jsValue(array),path,index,added, jsValue(removed)]);
}
@behavior
abstract class PolymerAutoNotifySupportMixin {
ObservablePolymerNotifier _observablePolymerNotifier;
static created(mixin) {
print("MIXIN CREATED CALLED !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!11");
}
void attached() {
_observablePolymerNotifier = new ObservablePolymerNotifier(this,this);
}
void detached() {
_observablePolymerNotifier.close();
_observablePolymerNotifier=null;
}
}
@jakemac53
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jakemac53 commented Sep 17, 2015

fyi, if you make your mixin be a behavior (annotate it with @behavior) then you can call startNotify in a static created method. Something like this:

@behavior
abstract class PolymerAutoNotifySupportMixin implements PolymerElement {
  ObservablePolymerNotifier _observablePolimerNotifier;

  // This would only be invoked with instances that mix in PolymerAutoNotifySupportMixin,
  // so you can reliably put that type here. I also added the implements clause above
  // which will give you access to all PolymerElement methods :). Best of both worlds!
  static created(PolymerAutoNotifySupportMixin instance) {
    instance.startNotify();
  }

  void startNotify() {
    _observablePolimerNotifier = new ObservablePolymerNotifier(this, this);
  }

  void stopNotify() {
    _observablePolimerNotifier.close();
    _observablePolimerNotifier=null;
  }
}

@dam0vm3nt
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dam0vm3nt commented Sep 17, 2015

Great! I will definitely follow your advice.

@dam0vm3nt
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dam0vm3nt commented Sep 18, 2015

I made some changes using attached and detached callback and polishing a bit.
I'm going to write a smoke transformer to make the thing work with dart2js too and/or patch observable to carry String field info (shouldn't be too difficult to modify the PropertyChangeEvent and the transformer) along with symbol thus to garantee retrocompatibilty and to submit a pull request.
I will package this little thing and submit to pub for public utility.

@dam0vm3nt
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dam0vm3nt commented Sep 18, 2015

I turns out smoke and some reflection is indeed necessary otherwise we don't get notifications for initial values.

@dam0vm3nt
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dam0vm3nt commented Sep 18, 2015

Added _notifySplice and ObservableList support.

@jakemac53
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jakemac53 commented Sep 18, 2015

I would also use the static attached and detached methods, instead of the instance methods, otherwise they could be overridden by other mixins.

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