git ssb

1
var resolve = require('./resolve')
2
var LazyWatcher = require('./lib/lazy-watcher')
3
var isReferenceType = require('./lib/is-reference-type')
4
5
module.exports = Map
6
7
function Map (obs, lambda, opts) {
8
  var releases = []
9
  var binder = LazyWatcher(update, listen, unlisten)
10
11
  var lastValues = new global.Map()
12
  var items = []
13
14
  var raw = []
15
  var values = []
16
  var watches = []
17
18
  binder.value = values
19
20
  // incremental update
21
  var queue = []
22
  var maxTime = null
23
  if (opts && opts.maxTime) {
24
    maxTime = opts.maxTime
25
  }
26
27
  var result = function MutantMap (listener) {
28
    if (!listener) {
29
      return binder.getValue()
30
    }
31
    return binder.addListener(listener)
32
  }
33
34
  result.get = function (index) {
35
    return raw[index]
36
  }
37
38
  result.getLength = function (index) {
39
    return raw.length
40
  }
41
42
  result.includes = function (valueOrObs) {
43
    return !!~raw.indexOf(valueOrObs)
44
  }
45
46
  result.indexOf = function (valueOrObs) {
47
    return raw.indexOf(valueOrObs)
48
  }
49
50
  return result
51
52
  // scoped
53
54
  function listen () {
55
    if (typeof obs === 'function') {
56
      releases.push(obs(binder.onUpdate))
57
    }
58
    rebindAll()
59
  }
60
61
  function unlisten () {
62
    while (releases.length) {
63
      releases.pop()()
64
    }
65
    rebindAll()
66
    lastValues.clear()
67
  }
68
69
  function update () {
70
    var changed = false
71
72
    if (items.length !== getLength(obs)) {
73
      changed = true
74
    }
75
76
    var startedAt = Date.now()
77
78
    for (var i = 0, len = getLength(obs); i < len; i++) {
79
      var item = get(obs, i)
80
      var currentItem = items[i]
81
      items[i] = item
82
83
      if (typeof item === 'object' || item !== currentItem) {
84
        if (maxTime && Date.now() - startedAt > maxTime) {
85
          queueUpdateItem(i)
86
        } else {
87
          updateItem(i)
88
        }
89
        changed = true
90
      }
91
    }
92
93
    if (changed) {
94
      // clean up cache
95
      var oldLength = items.length
96
      Array.from(lastValues.keys()).filter(notIncluded, obs).forEach(deleteEntry, lastValues)
97
      items.length = getLength(obs)
98
      values.length = items.length
99
      raw.length = items.length
100
      for (var index = items.length; index < oldLength; index++) {
101
        rebind(index)
102
      }
103
    }
104
105
    return changed
106
  }
107
108
  function queueUpdateItem (i) {
109
    if (!queue.length) {
110
      setImmediate(flushQueue)
111
    }
112
    if (!~queue.indexOf(i)) {
113
      queue.push(i)
114
    }
115
  }
116
117
  function flushQueue () {
118
    var startedAt = Date.now()
119
    while (queue.length && (!maxTime || Date.now() - startedAt < maxTime)) {
120
      updateItem(queue.pop())
121
    }
122
    binder.broadcast()
123
    if (queue.length) {
124
      setImmediate(flushQueue)
125
    }
126
  }
127
128
  function updateItem (i) {
129
    var item = get(obs, i)
130
    if (isReferenceType(item)) {
131
      raw[i] = lambda(item)
132
    } else {
133
      if (!lastValues.has(item)) {
134
        lastValues.set(item, lambda(item))
135
      }
136
      raw[i] = lastValues.get(item)
137
    }
138
    values[i] = resolve(raw[i])
139
    rebind(i)
140
  }
141
142
  function rebind (index) {
143
    if (watches[index]) {
144
      watches[index]()
145
      watches[index] = null
146
    }
147
148
    if (binder.live) {
149
      if (typeof raw[index] === 'function') {
150
        watches[index] = updateValue(raw[index], index)
151
      }
152
    }
153
  }
154
155
  function rebindAll () {
156
    for (var i = 0; i < raw.length; i++) {
157
      rebind(i)
158
    }
159
  }
160
161
  function updateValue (obs, index) {
162
    return obs(function (value) {
163
      if (values[index] !== value || typeof value === 'object') {
164
        values[index] = value
165
        binder.broadcast()
166
      }
167
    })
168
  }
169
}
170
171
function get (target, index) {
172
  if (typeof target === 'function' && !target.get) {
173
    target = target()
174
  }
175
176
  if (Array.isArray(target)) {
177
    return target[index]
178
  } else if (target && target.get) {
179
    return target.get(index)
180
  }
181
}
182
183
function getLength (target) {
184
  if (typeof target === 'function' && !target.getLength) {
185
    target = target()
186
  }
187
188
  if (Array.isArray(target)) {
189
    return target.length
190
  } else if (target && target.get) {
191
    return target.getLength()
192
  }
193
194
  return 0
195
}
196
197
function notIncluded (value) {
198
  if (this.includes) {
199
    return !this.includes(value)
200
  } else if (this.indexOf) {
201
    return !~this.indexOf(value)
202
  } else if (typeof this === 'function') {
203
    var array = this()
204
    if (array && array.includes) {
205
      return !array.includes(value)
206
    }
207
  }
208
  return true
209
}
210
211
function deleteEntry (entry) {
212
  this.delete(entry)
213
}
214