@n1ru4l/toposort/main.js

toposort using modern ecma script data structures

const toposort = (dag) => {
    const inDegrees = countInDegrees(dag);
    let { roots, nonRoots } = getRootsAndNonRoots(inDegrees);
    const sorted = [];
    while (roots.size) {
        sorted.push(roots);
        const newRoots = new Set();
        for (const root of roots) {
            for (const dependent of dag.get(root)) {
                inDegrees.set(dependent, inDegrees.get(dependent) - 1);
                if (inDegrees.get(dependent) === 0) {
                    newRoots.add(dependent);
                }
            }
        }
        roots = newRoots;
    }
    nonRoots = getRootsAndNonRoots(inDegrees).nonRoots;
    if (nonRoots.size) {
        throw Error("Cycle(s) detected; toposort only works on acyclic graphs");
    }
    return sorted;
};
const toposortReverse = (deps) => {
    const dag = reverse(deps);
    return toposort(dag);
};
const countInDegrees = (dag) => {
    var _a, _b;
    const counts = new Map();
    for (const [vx, dependents] of dag.entries()) {
        counts.set(vx, (_a = counts.get(vx)) !== null && _a !== void 0 ? _a : 0);
        for (const dependent of dependents) {
            counts.set(dependent, ((_b = counts.get(dependent)) !== null && _b !== void 0 ? _b : 0) + 1);
        }
    }
    return counts;
};
const getRootsAndNonRoots = (counts) => {
    const roots = new Set();
    const nonRoots = new Set();
    for (const [id, deg] of counts.entries()) {
        if (deg === 0) {
            roots.add(id);
        }
        else if (deg !== 0) {
            nonRoots.add(id);
        }
    }
    return { roots, nonRoots };
};
const reverse = (deps) => {
    const reversedDeps = new Map();
    for (const [name, dependsOn] of deps.entries()) {
        let set = reversedDeps.get(name);
        if (set === undefined) {
            set = new Set();
            reversedDeps.set(name, set);
        }
        for (const dependsOnName of dependsOn) {
            let set = reversedDeps.get(dependsOnName);
            if (set === undefined) {
                set = new Set();
                reversedDeps.set(dependsOnName, set);
            }
            set.add(name);
        }
    }
    return reversedDeps;
};

export { toposort, toposortReverse };