98 lines
2.5 KiB
Markdown
98 lines
2.5 KiB
Markdown
# Toposort
|
|
|
|
Sort directed acyclic graphs
|
|
|
|
[](https://travis-ci.org/marcelklehr/toposort)
|
|
|
|
## Installation
|
|
|
|
`npm install toposort` or `component install marcelklehr/toposort`
|
|
|
|
then in your code:
|
|
|
|
```js
|
|
toposort = require('toposort')
|
|
```
|
|
|
|
## Usage
|
|
We want to sort the following graph.
|
|
|
|
|
|
|
|
```js
|
|
// First, we define our edges.
|
|
var graph = [
|
|
['put on your shoes', 'tie your shoes']
|
|
, ['put on your shirt', 'put on your jacket']
|
|
, ['put on your shorts', 'put on your jacket']
|
|
, ['put on your shorts', 'put on your shoes']
|
|
]
|
|
|
|
|
|
// Now, sort the vertices topologically, to reveal a legal execution order.
|
|
toposort(graph)
|
|
// [ 'put on your shirt'
|
|
// , 'put on your shorts'
|
|
// , 'put on your jacket'
|
|
// , 'put on your shoes'
|
|
// , 'tie your shoes' ]
|
|
```
|
|
|
|
(Note that there is no defined order for graph parts that are not connected
|
|
-- you could also put on your jacket after having tied your shoes...)
|
|
|
|
### Sorting dependencies
|
|
It is usually more convenient to specify *dependencies* instead of "sequences".
|
|
```js
|
|
// This time, edges represent dependencies.
|
|
var graph = [
|
|
['tie your shoes', 'put on your shoes']
|
|
, ['put on your jacket', 'put on your shirt']
|
|
, ['put on your shoes', 'put on your shorts']
|
|
, ['put on your jacket', 'put on your shorts']
|
|
]
|
|
|
|
toposort(graph)
|
|
// [ 'tie your shoes'
|
|
// , 'put on your shoes'
|
|
// , 'put on your jacket'
|
|
// , 'put on your shirt'
|
|
// , 'put on your shorts' ]
|
|
|
|
// Now, reversing the list will reveal a legal execution order.
|
|
toposort(graph).reverse()
|
|
// [ 'put on your shorts'
|
|
// , 'put on your shirt'
|
|
// , 'put on your jacket'
|
|
// , 'put on your shoes'
|
|
// , 'tie your shoes' ]
|
|
```
|
|
|
|
## API
|
|
|
|
### toposort(edges)
|
|
|
|
+ edges {Array} An array of directed edges describing a graph. An edge looks like this: `[node1, node2]` (vertices needn't be strings but can be of any type).
|
|
|
|
Returns: {Array} a list of vertices, sorted from "start" to "end"
|
|
|
|
Throws an error if there are any cycles in the graph.
|
|
|
|
### toposort.array(nodes, edges)
|
|
|
|
+ nodes {Array} An array of nodes
|
|
+ edges {Array} An array of directed edges. You don't need to mention all `nodes` here.
|
|
|
|
This is a convenience method that allows you to define nodes that may or may not be connected to any other nodes. The ordering of unconnected nodes is not defined.
|
|
|
|
Returns: {Array} a list of vertices, sorted from "start" to "end"
|
|
|
|
Throws an error if there are any cycles in the graph.
|
|
|
|
## Tests
|
|
|
|
Run the tests with `node test.js`.
|
|
|
|
## Legal
|
|
|
|
MIT License
|