README.md

topo-kahn

Topological sort (Kahn algorithm) an oriented graph containing any kind of node, using ES6 Maps & Sets.

Examples

let's start with some family members :

import sort, { reverseMatrix } from topo-kahn ;

const g = { name: "George" };
const mt = { name: "Marie-Thérèse" };
const p = { name: "Patrice" };
const j = { name: "Josette" };
const pj = { name: "Pierre-Jean" };
const m = { name: "Mathias" };
const pandj = new Set([p, j]);

...

Static style, by passing a Map that represents dependency matrix

...

const parents = new Map([
  [m, pandj],
  [g, null],
  [pj, pandj],
  [mt, null],
  [p, new Set([g, mt])],
  [j, null],
]);

const sorted = sort(parents); // sorted = new Set([g, mt, j, p, pj, m]);

Functional style, by passing a Set that represents family members and a generator function

...

const family = new Set([m, g, pj, mt, p, j]);

const getParents = member => {
  switch (member) {
    case m:
      return pandj;
    case g:
      return null;
    case pj:
      return pandj;
    case mt:
      return null;
    case p:
      return new Set([g, mt]);
    case j:
    default:
      return null;
  }
};

const sorted = sort(family, { generator: getParents }); // same result !

You can even pass a reversed matrix / generator and work the other way around !

// reverseMatrix is a util function provided by this package
const sorted = sort(reverseMatrix(parents), { type: 'children' }); // same result !

// or

const sorted = sort(family, { generator: getChildren, type: 'children' }); // same result !

FAQ

• Why should I use it ?
  • If you like this way to express a graph
  • Or if you already have a function that defines dependencies between nodes
  • If you want / need to define any kind of node (objects, strings, numbers, ...) by using ES6 Maps & Sets
• What if there's a loop in my graph ? topo-kahn will throw an error
• What if I have a matrix containing node's children, and not parents ? Just pass a type option set to children

import sort from topo-kahn ;

const sorted = sort(children, { type: 'children' });
// eq. to const sorted = sort(parents);

Reverse a matrix

topo-kahn exports a specific function called reverseMatrix if you need to.