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