tuple-stream2

Merges multiple streams into an aligned tuple stream.

Example

var through = require("through2")
var TupleStream = require("tuple-stream2")
 
// an object map of streams, but could also be an array
var stooges = {
  before: through.obj(),
  after: through.obj()
}
 
stooges.before.write({id: 1, name: "Moe"})
stooges.before.write({id: 2, name: "Shemp"})
stooges.before.write({id: 3, name: "Larry"})
stooges.before.end()
 
stooges.after.write({id: 1, name: "Moe"})
stooges.after.write({id: 3, name: "Larry"})
stooges.after.write({id: 4, name: "Curly"})
stooges.after.end()
 
function comparator(a, b){ return !a ? 1 : !b ? -1 : a.id - b.id }
 
var tuples = TupleStream(stooges, {comparator: comparator})
 
tuples.on("data", console.log)
 
//  {before: {id: 1, name: "Moe"  }, after: {id: 1, name: "Moe"}  },
//  {before: {id: 3, name: "Larry"}, after: {id: 3, name: "Larry"}},
//  {before: {id: 2, name: "Shemp"}                               },
//  {                                after: {id: 4, name: "Curly"}}

API

TupleStream(streams, [options])

Returns a readable stream.

streams is a required object or array of readable streams.

options is an optional object that can contain the following key:

• comparator: an optional function used to sort streams. It follows the specification used for Array.prototype.sort, and defaults to function(){ return 0 }.

The returned stream emits values with the same keys as streams, but with stream data instead of streams for the values.