git ssb

1
var Value = require('./value')
2
var LazyWatcher = require('./lib/lazy-watcher')
3
var isSame = require('./lib/is-same')
4
5
module.exports = Struct
6
7
var blackList = {
8
  'length': 'Clashes with `Function.prototype.length`.\n',
9
  'name': 'Clashes with `Function.prototype.name`\n',
10
  'destroy': '`destroy` is a reserved key of struct\n'
11
}
12
13
function Struct (properties, opts) {
14
  var object = Object.create({})
15
  var releases = []
16
  var binder = LazyWatcher(update, listen, unlisten)
17
  binder.value = object
18
19
  if (opts && opts.nextTick) binder.nextTick = true
20
  if (opts && opts.idle) binder.idle = true
21
22
  var comparer = opts && opts.comparer || null
23
24
  var observable = function MutantStruct (listener) {
25
    if (!listener) {
26
      return binder.getValue()
27
    }
28
    return binder.addListener(listener)
29
  }
30
31
  var keys = Object.keys(properties)
32
  var suspendBroadcast = false
33
34
  keys.forEach(function (key) {
35
    if (blackList.hasOwnProperty(key)) {
36
      throw new Error("Cannot create a struct with a key named '" + key + "'.\n" + blackList[key])
37
    }
38
39
    var obs = typeof properties[key] === 'function'
40
      ? properties[key]
41
      : Value(properties[key])
42
43
    object[key] = obs()
44
    observable[key] = obs
45
  })
46
47
  observable.set = function (values) {
48
    var lastValue = suspendBroadcast
49
    suspendBroadcast = true
50
    values = values || {}
51
52
    // update inner observables
53
    keys.forEach(function (key) {
54
      if (observable[key]() !== values[key]) {
55
        observable[key].set(values[key])
56
      }
57
    })
58
59
    // store additional keys (but don't create observables)
60
    Object.keys(values).forEach(function (key) {
61
      if (!(key in properties)) {
62
        object[key] = values[key]
63
      }
64
    })
65
66
    suspendBroadcast = lastValue
67
    if (!suspendBroadcast) {
68
      binder.broadcast()
69
    }
70
  }
71
72
  return observable
73
74
  // scoped
75
76
  function listen () {
77
    keys.map(function (key) {
78
      var obs = observable[key]
79
      releases.push(obs(function (val) {
80
        if (!isSame(val, object[key], comparer)) {
81
          object[key] = val
82
          if (!suspendBroadcast) {
83
            binder.broadcast(object)
84
          }
85
        }
86
      }))
87
    })
88
  }
89
90
  function unlisten () {
91
    while (releases.length) {
92
      releases.pop()()
93
    }
94
  }
95
96
  function update () {
97
    var changed = false
98
    keys.forEach(function (key) {
99
      var newValue = observable[key]()
100
      if (!isSame(newValue, object[key], comparer)) {
101
        object[key] = observable[key]()
102
        changed = true
103
      }
104
    })
105
    return changed
106
  }
107
}
108