topo

What is topo?

The 'topo' npm package is a module that provides a way to manage topological sorting of nodes with dependencies. It is useful for scenarios where you need to order items based on their dependencies, ensuring that each item appears after its dependencies have been processed.

What are topo's main functionalities?

Adding Nodes

This feature allows you to add nodes to the topo instance. Each node can be assigned to a group and can specify dependencies using the 'after' and 'before' options.

const Topo = require('topo');
const topo = new Topo();
topo.add('a', { group: 'group1' });
topo.add('b', { group: 'group2', after: ['group1'] });
console.log(topo.nodes);

Sorting Nodes

This feature sorts the nodes based on their dependencies. The 'sort' method returns an array of nodes in the correct order, ensuring that each node appears after its dependencies.

const Topo = require('topo');
const topo = new Topo();
topo.add('a', { group: 'group1' });
topo.add('b', { group: 'group2', after: ['group1'] });
topo.add('c', { group: 'group3', before: ['group2'] });
const sorted = topo.sort();
console.log(sorted);

Handling Cyclic Dependencies

This feature demonstrates how the topo package handles cyclic dependencies. If a cyclic dependency is detected, an error is thrown, preventing the sort operation from completing.

const Topo = require('topo');
const topo = new Topo();
topo.add('a', { group: 'group1' });
topo.add('b', { group: 'group2', after: ['group1'] });
topo.add('c', { group: 'group3', after: ['group2', 'group1'] });
topo.add('d', { group: 'group4', after: ['group3', 'group1'] });
try {
  topo.add('e', { group: 'group5', after: ['group4', 'group1', 'group3'] });
  topo.add('f', { group: 'group6', after: ['group5', 'group2'] });
  const sorted = topo.sort();
  console.log(sorted);
} catch (err) {
  console.error('Cyclic dependency detected:', err.message);
}

Other packages similar to topo

dependency-graph

The 'dependency-graph' package provides a similar functionality for managing and sorting dependencies. It allows you to create a directed graph of dependencies and sort them topologically. Compared to 'topo', 'dependency-graph' offers more flexibility in terms of graph manipulation and querying.

graphlib

The 'graphlib' package is a general-purpose graph library that supports directed and undirected graphs. It includes algorithms for topological sorting, shortest paths, and more. While 'graphlib' is more comprehensive and versatile, 'topo' is more focused on topological sorting with a simpler API.

toposort

The 'toposort' package is a lightweight library specifically designed for topological sorting. It provides a straightforward API for adding nodes and dependencies and then sorting them. 'toposort' is simpler and more focused compared to 'topo', which offers additional features like grouping and handling cyclic dependencies.

README

topo

Topological sorting with grouping support.

Lead Maintainer: Devin Ivy

Usage

See the API Reference

Example

const Topo = require('topo');

const morning = new Topo();

morning.add('Nap', { after: ['breakfast', 'prep'] });

morning.add([
    'Make toast',
    'Pour juice'
], { before: 'breakfast', group: 'prep' });

morning.add('Eat breakfast', { group: 'breakfast' });

morning.nodes;        // ['Make toast', 'Pour juice', 'Eat breakfast', 'Nap']