README.md

@qiwi/toposort

Fork of toposort with updated dependencies and some new features

Why?

Toposort is wonderful, but we also need to know which parts of graph can be handled in parallel mode.

You can simultaneously handle unconnected parts (components in graph theory) of a graph.

Also, you can analyze dependencies and dependants of graph nodes to find independent nodes to parallelize their processing.

So, toposortExtra returns maps of dependencies and dependants and a list of graph components.

Installation

yarn add @qiwi/toposort

npm i @qiwi/toposort

Usage

toposortExtra({ nodes, edges, throwOnCycle })

Returns an array of the graph components

The graph above is used in the code below.

import { toposortExtra } from '@qiwi/toposort'

const res = toposortExtra({ edges: [[1, 3], [1, 2], [2, 4], [2, 5], [6, 7], [6, 8], [9, 8]] }) // see diagramm above

console.log(res)
/*
{
      sources: [1, 6, 9], // nodes which do not have incoming edges, e.g. dependencies/parents
      prev: new Map([ // map of dependencies
        [1, []],
        [3, [1]],
        [2, [1]],
        [4, [2]],
        [5, [2]],
        [6, []],
        [7, [6]],
        [8, [6, 9]],
        [9, []],
      ]),
      next: new Map([ // map of dependants
        [1, [2, 3]],
        [3, []],
        [2, [4, 5]],
        [4, []],
        [5, []],
        [6, [7, 8]],
        [7, []],
        [8, []],
        [9, [8]],
      ]),
      graphs: [ // list of graph components (unconnected parts)
        {
          nodes: [1, 2, 3, 4, 5], // list of component nodes
          sources: [1] // list of component start nodes 
        },
        {
          nodes: [6, 7, 8, 9],
          sources: [6, 9]
        }
      ]
    }
 */

The same result, but also checks edge nodes to be in the nodes list

const res = toposortExtra({
  nodes: [1, 2, 3, 4, 5, 6, 7, 8, 9],
  edges: [[1, 3], [1, 2], [2, 4], [2, 5], [6, 7], [6, 8], [9, 8]]
})
console.log(res) // the same result

const res = toposortExtra({
  nodes: [1, 2, 3, 4, 6, 7, 8, 9],
  edges: [[1, 3], [1, 2], [2, 4], [2, 5], [6, 7], [6, 8], [9, 8]]
}) // Uncaught Error: Unknown node. There is an unknown node in the supplied edges.

You can also check the graph to be acyclic

toposortExtra({
  edges: [[1, 2], [2, 3], [3, 1]],
  throwOnCycle: true
}) // Uncaught Error: Cyclic dependency, node was:1

toposort(edges)

Marcelklehr's original toposort

import toposort from '@qiwi/toposort' 

console.log(toposort([
    [ '3', '2' ],
    [ '2', '1' ],
    [ '6', '5' ],
    [ '5', '2' ],
    [ '5', '4' ]
  ]
)) // [ '3', '6', '5', '2', '1', '4' ]

array(nodes, edges)

Marcelklehr's original toposort.array.

Checks edge nodes for presence in the nodes array

import { array } from '@qiwi/toposort' 

console.log(array(
  ['1', '2', '3', '4', '5', '6'],
  [
    [ '3', '2' ],
    [ '2', '1' ],
    [ '6', '5' ],
    [ '5', '2' ],
    [ '5', '4' ]
  ]
)) // [ '3', '6', '5', '2', '1', '4' ]