port TemplateBinding to ed3266266e751b5ab1f75f8e0509d0d5f0ef35d8

pkg/observe/lib/src/compound_binding.dart

Index: pkg/observe/lib/src/compound_binding.dart
diff --git a/pkg/observe/lib/src/compound_binding.dart b/pkg/observe/lib/src/compound_binding.dart
deleted file mode 100644
index 86773d9992838bbff2c077cd3cc9570c28a3e95a..0000000000000000000000000000000000000000
--- a/pkg/observe/lib/src/compound_binding.dart
+++ /dev/null
@@ -1,136 +0,0 @@
-// 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.compound_binding;
-
-import 'dart:async';
-import 'package:observe/observe.dart';
-
-/** The callback used in the [CompoundBinding.combinator] field. */
-typedef Object CompoundBindingCombinator(Map objects);
-
-/**
- * CompoundBinding is an object which knows how to listen to multiple path
- * values (registered via [bind]) and invoke its [combinator] when one or more
- * of the values have changed and set its [value] property to the return value
- * of the function. When any value has changed, all current values are provided
- * to the [combinator] in the single `values` argument.
- *
- * For example:
- *
- *     var binding = new CompoundBinding((values) {
- *       var combinedValue;
- *       // compute combinedValue based on the current values which are provided
- *       return combinedValue;
- *     });
- *     binding.bind('name1', obj1, path1);
- *     binding.bind('name2', obj2, path2);
- *     //...
- *     binding.bind('nameN', objN, pathN);
- */
-// TODO(jmesserly): rename to something that indicates it's a computed value?
-class CompoundBinding extends ChangeNotifier {
-  CompoundBindingCombinator _combinator;
-
-  // TODO(jmesserly): ideally these would be String keys, but sometimes we
-  // use integers.
-  Map<dynamic, StreamSubscription> _observers = new Map();
-  Map _values = new Map();
-  Object _value;
-
-  /**
-   * True if [resolve] is scheduled. You can set this to true if you plan to
-   * call [resolve] manually, avoiding the need for scheduling an asynchronous
-   * resolve.
-   */
-  // TODO(jmesserly): I don't like having this public, is the optimization
-  // really needed? "scheduleMicrotask" in Dart should be pretty cheap.
-  bool scheduled = false;
-
-  /**
-   * Creates a new CompoundBinding, optionally proving the [combinator] function
-   * for computing the value. You can also set [schedule] to true if you plan
-   * to invoke [resolve] manually after initial construction of the binding.
-   */
-  CompoundBinding([CompoundBindingCombinator combinator]) {
-    // TODO(jmesserly): this is a tweak to the original code, it seemed to me
-    // that passing the combinator to the constructor should be equivalent to
-    // setting it via the property.
-    // I also added a null check to the combinator setter.
-    this.combinator = combinator;
-  }
-
-  CompoundBindingCombinator get combinator => _combinator;
-
-  set combinator(CompoundBindingCombinator combinator) {
-    _combinator = combinator;
-    if (combinator != null) _scheduleResolve();
-  }
-
-  int get length => _observers.length;
-
-  @reflectable get value => _value;
-
-  @reflectable void set value(newValue) {
-    _value = notifyPropertyChange(#value, _value, newValue);
-  }
-
-  void bind(name, model, String path) {
-    unbind(name);
-
-     // TODO(jmesserly): should we delay observing until we are observed,
-     // similar to PathObserver?
-    _observers[name] = new PathObserver(model, path).bindSync((value) {
-      _values[name] = value;
-      _scheduleResolve();
-    });
-  }
-
-  void unbind(name, {bool suppressResolve: false}) {
-    var binding = _observers.remove(name);
-    if (binding == null) return;
-
-    binding.cancel();
-    _values.remove(name);
-    if (!suppressResolve) _scheduleResolve();
-  }
-
-  // TODO(rafaelw): Is this the right processing model?
-  // TODO(rafaelw): Consider having a seperate ChangeSummary for
-  // CompoundBindings so to excess dirtyChecks.
-  void _scheduleResolve() {
-    if (scheduled) return;
-    scheduled = true;
-    scheduleMicrotask(resolve);
-  }
-
-  void resolve() {
-    if (_observers.isEmpty) return;
-    scheduled = false;
-
-    if (_combinator == null) {
-      throw new StateError(
-          'CompoundBinding attempted to resolve without a combinator');
-    }
-
-    value = _combinator(_values);
-  }
-
-  /**
-   * Closes the observer.
-   *
-   * This happens automatically if the [value] property is no longer observed,
-   * but this can also be called explicitly.
-   */
-  void close() {
-    for (var binding in _observers.values) {
-      binding.cancel();
-    }
-    _observers.clear();
-    _values.clear();
-    value = null;
-  }
-
-  unobserved() => close();
-}