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1 // Copyright (c) 2015, the Dartino project authors. Please see the AUTHORS file | |
2 // for details. All rights reserved. Use of this source code is governed by a | |
3 // BSD-style license that can be found in the LICENSE.md file. | |
4 | |
5 import 'model.dart'; | |
6 import 'dart/todomvc_presenter.dart'; | |
7 import 'dart/todomvc_presenter_model.dart'; | |
8 | |
9 import 'dart/presentation_graph.dart' as node; | |
10 | |
11 class ItemPair { | |
12 final Item item; | |
13 final Immutable presentation; | |
14 ItemPair(this.item, this.presentation); | |
15 } | |
16 | |
17 class TodoMVCImpl extends TodoMVCPresenter { | |
18 | |
19 Model _model = new Model(); | |
20 | |
21 TodoMVCImpl() { | |
22 _model.createItem("My default todo"); | |
23 _model.createItem("Some other todo"); | |
24 } | |
25 | |
26 void createItem(title) { | |
27 _model.createItem(title.str); | |
28 } | |
29 | |
30 void clearItems() { | |
31 _model.clearItems(); | |
32 } | |
33 | |
34 // Cache of previously drawn items. | |
35 // TODO(zerny): use a map once we have a proper implementation. | |
36 List<ItemPair> _cachePrevious = new List(); | |
37 List<ItemPair> _cacheCurrent = new List(); | |
38 | |
39 Immutable _lookup(Item item, int index) { | |
40 // Look for a cached item in the range [index; index + 1] | |
41 for (var i = 0; i < 2; ++i) { | |
42 var j = index + i; | |
43 if (j >= _cachePrevious.length) return null; | |
44 ItemPair cached = _cachePrevious[j]; | |
45 if (cached.item == item) return cached.presentation; | |
46 } | |
47 return null; | |
48 } | |
49 | |
50 void _add(int index, Item item, Immutable presentation) { | |
51 _cacheCurrent[index] = new ItemPair(item, presentation); | |
52 } | |
53 | |
54 Immutable render(previous) { | |
55 // Swap previous and current cache and resize current to model-item count. | |
56 var tmp = _cachePrevious; | |
57 tmp.length = _model.todos.length; | |
58 _cachePrevious = _cacheCurrent; | |
59 _cacheCurrent = tmp; | |
60 return _renderList(0, previous); | |
61 } | |
62 | |
63 Immutable _renderList(int index, Immutable previous) => | |
64 (index == _model.todos.length) | |
65 ? node.nil(previous) | |
66 : node.cons( | |
67 _renderItemFromCache(index, node.getConsFst(previous)), | |
68 _renderList(index + 1, node.getConsSnd(previous)), | |
69 null, | |
70 null, | |
71 null, | |
72 previous); | |
73 | |
74 Immutable _renderItemFromCache(int index, Immutable previous) { | |
75 Item item = _model.todos[index]; | |
76 Cons cached = _lookup(item, index); | |
77 Immutable current = (cached == null) | |
78 ? _renderItem(item, previous) | |
79 : node.cons( | |
80 node.str(item.title, cached.fst), | |
81 node.truth(item.done, cached.snd), | |
82 // Reuse the handlers since we know that item is the same as the | |
83 // item used for the creating the cached handlers. | |
84 cached.deleteEvent, | |
85 cached.completeEvent, | |
86 cached.uncompleteEvent, | |
87 cached); | |
88 _add(index, item, current); | |
89 return current; | |
90 } | |
91 | |
92 Immutable _renderItem(Item item, Immutable previous) => | |
93 node.cons( | |
94 node.str(item.title, node.getConsFst(previous)), | |
95 node.truth(item.done, node.getConsSnd(previous)), | |
96 new EventHandler(() { _model.todos.remove(item); }), | |
97 new EventHandler(item.complete), | |
98 new EventHandler(item.uncomplete)); | |
99 } | |
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