pull-cursor

pull-cursor

A pull-stream over series that have an index.

I wrote this to abstract out streams for flumelog-offset it makes flexible streams on ranges easy, including live streams!

api

var inject = require('pull-cursor')

inject(since, getMeta) => createStream(opts)

since is an obv instance, which represents the current length of the dataset. getMeta is a function that takes an offset, an option to use caching and callback the value plus the next and prev offsets.

var Obv = require('obv')
var since = Obv()

//dummy example with an array as the datastore
var ary = ['A', 'B', 'C', 'D']
since.set(ary.length - 1) //set since to last index!

var createStream = require('pull-cursor')(
  since,
  function (offset, useCache, cb) {
    if(offset < 0 || offset >= ary.length)
      return cb(new Error('out of bounds:'+offset)

    cb(null, ary[offset], offset-1, offset+1)

  })

createStream(opts) => Source

createStream now accepts all the typical options of a levelup or flumedb stream. including

• reverse (boolean) read backwards
• live (boolean) include new items
• old (boolean) include old items (set to false implies live)
• gt (offset) items greater than a valid offset
• gte (offset) items greater or equal to a valid offset
• lt (offset) items less than a given offset
• lte (offset) items less than or equal to a given offset
• limit (number) stop after N items.
• cache (boolean) use cache of underlying

License

MIT