git ssb

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