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