git ssb

1
function NotFound (key) {
2
  var err = new Error('Not Found:'+key)
3
  err.notFound = true
4
  return err
5
}
6
7
module.exports = function (hash, matches, get) {
8
  return function (buffer, slots) {
9
    var self
10
    var size = 4
11
    var count = 0
12
    if(!buffer) {
13
      buffer = new Buffer(size*slots)
14
      buffer.fill(0)
15
    }
16
    else {
17
      slots = buffer.length/size
18
      count = buffer.readUInt32BE(0)
19
    }
20
    function _get (i) {
21
      return buffer.readUInt32BE((i%slots)*size)
22
    }
23
    function _set (i, v) {
24
      buffer.writeUInt32BE(v, (i%slots)*size)
25
    }
26
27
    return self = {
28
      get: function (key, cb) {
29
        ;(function next (i) {
30
          var k = _get(i)
31
          if(k === 0)
32
            cb(NotFound(key))
33
          else
34
            get(k, function (err, data) {
35
              if(err) cb(err)
36
              else if(matches(data, key)) cb(null, data)
37
              else next(i + 1)
38
            })
39
        })(hash(key))
40
      },
41
      _get: _get,
42
      add: function (key, value) {
43
        var i = hash(key)
44
        while(_get(i) !== 0) i++
45
        //buffer.writeUInt32BE(value, (i%slots)*size)
46
        _set(i, value)
47
        self.count = ++count
48
        return i
49
      },
50
      buffer: buffer
51
    }
52
  }
53
}
54