pad.pub0.org/node/pluginfw/tsort.js

113 lines
2.4 KiB
JavaScript

/**
* general topological sort
* from https://gist.github.com/1232505
* @author SHIN Suzuki (shinout310@gmail.com)
* @param Array<Array> edges : list of edges. each edge forms Array<ID,ID> e.g. [12 , 3]
*
* @returns Array : topological sorted list of IDs
**/
function tsort(edges) {
var nodes = {}, // hash: stringified id of the node => { id: id, afters: lisf of ids }
sorted = [], // sorted list of IDs ( returned value )
visited = {}; // hash: id of already visited node => true
var Node = function(id) {
this.id = id;
this.afters = [];
}
// 1. build data structures
edges.forEach(function(v) {
var from = v[0], to = v[1];
if (!nodes[from]) nodes[from] = new Node(from);
if (!nodes[to]) nodes[to] = new Node(to);
nodes[from].afters.push(to);
});
// 2. topological sort
Object.keys(nodes).forEach(function visit(idstr, ancestors) {
var node = nodes[idstr],
id = node.id;
// if already exists, do nothing
if (visited[idstr]) return;
if (!Array.isArray(ancestors)) ancestors = [];
ancestors.push(id);
visited[idstr] = true;
node.afters.forEach(function(afterID) {
if (ancestors.indexOf(afterID) >= 0) // if already in ancestors, a closed chain exists.
throw new Error('closed chain : ' + afterID + ' is in ' + id);
visit(afterID.toString(), ancestors.map(function(v) { return v })); // recursive call
});
sorted.unshift(id);
});
return sorted;
}
/**
* TEST
**/
function tsortTest() {
// example 1: success
var edges = [
[1, 2],
[1, 3],
[2, 4],
[3, 4]
];
var sorted = tsort(edges);
console.log(sorted);
// example 2: failure ( A > B > C > A )
edges = [
['A', 'B'],
['B', 'C'],
['C', 'A']
];
try {
sorted = tsort(edges);
}
catch (e) {
console.log(e.message);
}
// example 3: generate random edges
var max = 100, iteration = 30;
function randomInt(max) {
return Math.floor(Math.random() * max) + 1;
}
edges = (function() {
var ret = [], i = 0;
while (i++ < iteration) ret.push( [randomInt(max), randomInt(max)] );
return ret;
})();
try {
sorted = tsort(edges);
console.log("succeeded", sorted);
}
catch (e) {
console.log("failed", e.message);
}
}
// for node.js
if (typeof exports == 'object' && exports === this) {
module.exports = tsort;
if (process.argv[1] === __filename) tsortTest();
}