99 lines
2.2 KiB
JavaScript
99 lines
2.2 KiB
JavaScript
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/**
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* Topological sorting function
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*
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* @param {Array} edges
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* @returns {Array}
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*/
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module.exports = function(edges) {
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return toposort(uniqueNodes(edges), edges)
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}
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module.exports.array = toposort
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function toposort(nodes, edges) {
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var cursor = nodes.length
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, sorted = new Array(cursor)
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, visited = {}
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, i = cursor
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// Better data structures make algorithm much faster.
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, outgoingEdges = makeOutgoingEdges(edges)
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, nodesHash = makeNodesHash(nodes)
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// check for unknown nodes
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edges.forEach(function(edge) {
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if (!nodesHash.has(edge[0]) || !nodesHash.has(edge[1])) {
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throw new Error('Unknown node. There is an unknown node in the supplied edges.')
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}
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})
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while (i--) {
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if (!visited[i]) visit(nodes[i], i, new Set())
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}
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return sorted
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function visit(node, i, predecessors) {
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if(predecessors.has(node)) {
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var nodeRep
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try {
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nodeRep = ", node was:" + JSON.stringify(node)
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} catch(e) {
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nodeRep = ""
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}
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throw new Error('Cyclic dependency' + nodeRep)
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}
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if (!nodesHash.has(node)) {
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throw new Error('Found unknown node. Make sure to provided all involved nodes. Unknown node: '+JSON.stringify(node))
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}
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if (visited[i]) return;
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visited[i] = true
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var outgoing = outgoingEdges.get(node) || new Set()
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outgoing = Array.from(outgoing)
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if (i = outgoing.length) {
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predecessors.add(node)
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do {
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var child = outgoing[--i]
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visit(child, nodesHash.get(child), predecessors)
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} while (i)
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predecessors.delete(node)
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}
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sorted[--cursor] = node
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}
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}
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function uniqueNodes(arr){
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var res = new Set()
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for (var i = 0, len = arr.length; i < len; i++) {
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var edge = arr[i]
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res.add(edge[0])
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res.add(edge[1])
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}
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return Array.from(res)
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}
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function makeOutgoingEdges(arr){
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var edges = new Map()
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for (var i = 0, len = arr.length; i < len; i++) {
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var edge = arr[i]
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if (!edges.has(edge[0])) edges.set(edge[0], new Set())
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if (!edges.has(edge[1])) edges.set(edge[1], new Set())
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edges.get(edge[0]).add(edge[1])
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}
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return edges
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}
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function makeNodesHash(arr){
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var res = new Map()
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for (var i = 0, len = arr.length; i < len; i++) {
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res.set(arr[i], i)
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}
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return res
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}
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