subgraph

Content addressable graph where every node has at most a single link to another node

npm install subgraph

Usage

var subgraph = require('subgraph')
var sg = subgraph(levelupInstance)
 
var ws = sg.createAppendStream()
 
ws.write('hello')
ws.write('world')
 
ws.end(function () {
  var rs = sg.createReadStream(ws.key)
 
  rs.on('data', function (node) {
    console.log(node) // first {value: 'world'} then {value: 'hello'}
  })
})

API

var sg = subgraph(levelupInstance, [options])

Create a new subgraph instance. Options include:

{
  prefix: 'optional-sublevel-prefix'
}

var ws = sg.createAppendStream([link])

Create an append stream. The values you write to it will be linked together. When the stream emits finish it will have a .key property that contains the latest link and a .length property that contains the number of nodes written

Optionally you can provide a link in the constructor for the first node to append to.

var rs = sg.createReadStream(key)

Create a read stream from a key. Will read out values in reverse order of writes to the append stream.

var ws = sg.createWriteStream(key)

Create a write stream from a key. Will verify that the values written matches the key when hashed.

sg.add(link, value, [cb])

Shorthand for only adding a single value

sg.get(key, cb)

Shorthand for getting a single value

sg.root(key, cb)

Returns the root of a stream. If a write stream was ended prematurely / destroyed the root returned will have a link property.

sg.root(someKey, function (err, node) {
  console.log('root is', node)
  console.log('the stream is partially written?', !!root.link)
})

License

MIT