delete observe from the repo

pkg/observe/lib/src/list_path_observer.dart

-// Copyright (c) 2013, 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.
-
-library observe.src.list_path_observer;
-
-import 'dart:async';
-import 'package:observe/observe.dart';
-
-// Inspired by ArrayReduction at:
-// https://raw.github.com/rafaelw/ChangeSummary/master/util/array_reduction.js
-// The main difference is we support anything on the rich Dart Iterable API.
-
-/// Observes a path starting from each item in the list.
-@deprecated
-class ListPathObserver<E, P> extends ChangeNotifier {
-  final ObservableList<E> list;
-  final String _itemPath;
-  final List<PathObserver> _observers = <PathObserver>[];
-  StreamSubscription _sub;
-  bool _scheduled = false;
-  Iterable<P> _value;
-
-  ListPathObserver(this.list, String path)
-      : _itemPath = path {
-
-    // TODO(jmesserly): delay observation until we are observed.
-    _sub = list.listChanges.listen((records) {
-      for (var record in records) {
-        _observeItems(record.addedCount - record.removed.length);
-      }
-      _scheduleReduce(null);
-    });
-
-    _observeItems(list.length);
-    _reduce();
-  }
-
-  @reflectable Iterable<P> get value => _value;
-
-  void dispose() {
-    if (_sub != null) _sub.cancel();
-    _observers.forEach((o) => o.close());
-    _observers.clear();
-  }
-
-  void _reduce() {
-    _scheduled = false;
-    var newValue = _observers.map((o) => o.value);
-    _value = notifyPropertyChange(#value, _value, newValue);
-  }
-
-  void _scheduleReduce(_) {
-    if (_scheduled) return;
-    _scheduled = true;
-    scheduleMicrotask(_reduce);
-  }
-
-  void _observeItems(int lengthAdjust) {
-    if (lengthAdjust > 0) {
-      for (int i = 0; i < lengthAdjust; i++) {
-        int len = _observers.length;
-        var pathObs = new PathObserver(list, '[$len].$_itemPath');
-        pathObs.open(_scheduleReduce);
-        _observers.add(pathObs);
-      }
-    } else if (lengthAdjust < 0) {
-      for (int i = 0; i < -lengthAdjust; i++) {
-        _observers.removeLast().close();
-      }
-    }
-  }
-}