add topological sort utility

Author: RobinMalfait

packages/tailwindcss/src/utils/topological-sort.ts

@@ -0,0 +1,36 @@
+export function topologicalSort<Key>(
+  graph: Map<Key, Set<Key>>,
+  options: { onCircularDependency: (path: Key[], start: Key) => void },
+): Key[] {
+  let seen = new Set<Key>()
+  let wip = new Set<Key>()
+
+  let sorted: Key[] = []
+
+  function visit(node: Key, path: Key[] = []) {
+    if (!graph.has(node)) return
+    if (seen.has(node)) return
+
+    // Circular dependency detected
+    if (wip.has(node)) options.onCircularDependency?.(path, node)
+
+    wip.add(node)
+
+    for (let dependency of graph.get(node) ?? []) {
+      path.push(node)
+      visit(dependency, path)
+      path.pop()
+    }
+
+    seen.add(node)
+    wip.delete(node)
+
+    sorted.push(node)
+  }
+
+  for (let node of graph.keys()) {
+    visit(node)
+  }
+
+  return sorted
+}