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https://github.com/liitfr/topo-kahn

Topological sort (Kahn algorithm) an oriented graph containing any kind of node, using ES6 Maps & Sets.
https://github.com/liitfr/topo-kahn

dependency-graph dependency-resolution kahn kahns-alogrithm topological-order topological-sort

Last synced: 17 days ago
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Topological sort (Kahn algorithm) an oriented graph containing any kind of node, using ES6 Maps & Sets.

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# topo-kahn

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

## Examples

let's start with some family members :

```js
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

```js
...

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

```js
...

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 !

```js
// 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`

```js
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.