feat: add execution ordering analysis functions (topologicalOrder, parallelGroups, criticalPath, reachableFrom, ancestors, descendants)

src/analysis/index.ts

@@ -5,6 +5,14 @@ export {
   resolveDefaultNodeAttrs,
 } from "./defaults.js";
 export { typeCompat, type TypeCompatResult, type TypeMismatch } from "./type-compat.js";
+export {
+  topologicalOrder,
+  parallelGroups,
+  criticalPath,
+  reachableFrom,
+  ancestors,
+  descendants,
+} from "./ordering.js";
 export { buildTypeEdges } from "../graph/construction.js";
 export {
   validateSchema,

src/analysis/ordering.ts

@@ -0,0 +1,86 @@
+import { topologicalSort, topologicalGenerations, hasCycle } from "graphology-dag";
+import type { FlowGraph } from "../graph/construction.js";
+import { CycleError, NodeNotFoundError } from "../error/index.js";
+import { findCycles as findCyclesQuery, reachableFrom as reachableFromQuery, ancestors as ancestorsQuery, descendants as descendantsQuery } from "../graph/queries.js";
+
+export function topologicalOrder(graph: FlowGraph): string[] {
+  if (hasCycle(graph.graph)) {
+    const cycles = findCyclesQuery(graph.graph);
+    throw new CycleError(cycles);
+  }
+  return topologicalSort(graph.graph);
+}
+
+export function parallelGroups(graph: FlowGraph): string[][] {
+  if (hasCycle(graph.graph)) {
+    const cycles = findCyclesQuery(graph.graph);
+    throw new CycleError(cycles);
+  }
+  return topologicalGenerations(graph.graph);
+}
+
+export function criticalPath(graph: FlowGraph): string[] {
+  if (hasCycle(graph.graph)) {
+    const cycles = findCyclesQuery(graph.graph);
+    throw new CycleError(cycles);
+  }
+  const dg = graph.graph;
+  const depth = new Map<string, number>();
+  const topo = topologicalSort(dg);
+  for (const node of topo) {
+    const inNeighbors = dg.inNeighbors(node) ?? [];
+    let maxPredDepth = -1;
+    for (const pred of inNeighbors) {
+      const predDepth = depth.get(pred!) ?? 0;
+      if (predDepth > maxPredDepth) {
+        maxPredDepth = predDepth;
+      }
+    }
+    depth.set(node, maxPredDepth + 1);
+  }
+  let maxDepth = -1;
+  let endNode = "";
+  for (const node of topo) {
+    const d = depth.get(node) ?? 0;
+    if (d > maxDepth) {
+      maxDepth = d;
+      endNode = node;
+    }
+  }
+  if (topo.length === 0) return [];
+  const path: string[] = [endNode];
+  let current = endNode;
+  while (depth.get(current)! > 0) {
+    const inNeighbors = dg.inNeighbors(current) ?? [];
+    let bestPred = "";
+    let bestDepth = -1;
+    for (const pred of inNeighbors) {
+      const predDepth = depth.get(pred!) ?? 0;
+      if (predDepth > bestDepth) {
+        bestDepth = predDepth;
+        bestPred = pred!;
+      }
+    }
+    path.unshift(bestPred);
+    current = bestPred;
+  }
+  return path;
+}
+
+export function reachableFrom(graph: FlowGraph, nodeIds: string[]): Set<string> {
+  return reachableFromQuery(graph.graph, nodeIds);
+}
+
+export function ancestors(graph: FlowGraph, nodeId: string): string[] {
+  if (!graph.hasNode(nodeId)) {
+    throw new NodeNotFoundError(nodeId);
+  }
+  return ancestorsQuery(graph.graph, nodeId);
+}
+
+export function descendants(graph: FlowGraph, nodeId: string): string[] {
+  if (!graph.hasNode(nodeId)) {
+    throw new NodeNotFoundError(nodeId);
+  }
+  return descendantsQuery(graph.graph, nodeId);
+}

test/analysis/ordering.test.ts

@@ -0,0 +1,270 @@
+import { describe, it, expect } from "vitest";
+import { FlowGraph } from "../../src/graph/construction.js";
+import {
+  topologicalOrder,
+  parallelGroups,
+  criticalPath,
+  reachableFrom,
+  ancestors,
+  descendants,
+} from "../../src/analysis/ordering.js";
+import { CycleError, NodeNotFoundError } from "../../src/error/index.js";
+
+function buildDiamondDag(): FlowGraph {
+  const fg = new FlowGraph();
+  fg.addNode("top", { name: "top" });
+  fg.addNode("left", { name: "left" });
+  fg.addNode("right", { name: "right" });
+  fg.addNode("bottom", { name: "bottom" });
+  fg.addEdge("top", "left");
+  fg.addEdge("top", "right");
+  fg.addEdge("left", "bottom");
+  fg.addEdge("right", "bottom");
+  return fg;
+}
+
+function buildChainDag(): FlowGraph {
+  const fg = new FlowGraph();
+  fg.addNode("a", { name: "a" });
+  fg.addNode("b", { name: "b" });
+  fg.addNode("c", { name: "c" });
+  fg.addNode("d", { name: "d" });
+  fg.addEdge("a", "b");
+  fg.addEdge("b", "c");
+  fg.addEdge("c", "d");
+  return fg;
+}
+
+function buildWideDag(): FlowGraph {
+  const fg = new FlowGraph();
+  fg.addNode("root", { name: "root" });
+  fg.addNode("x", { name: "x" });
+  fg.addNode("y", { name: "y" });
+  fg.addNode("z", { name: "z" });
+  fg.addEdge("root", "x");
+  fg.addEdge("root", "y");
+  fg.addEdge("root", "z");
+  return fg;
+}
+
+function buildDisconnectedDag(): FlowGraph {
+  const fg = new FlowGraph();
+  fg.addNode("a", { name: "a" });
+  fg.addNode("b", { name: "b" });
+  fg.addNode("c", { name: "c" });
+  fg.addEdge("a", "b");
+  return fg;
+}
+
+describe("topologicalOrder (analysis)", () => {
+  it("returns topological order for a chain", () => {
+    const fg = buildChainDag();
+    expect(topologicalOrder(fg)).toEqual(["a", "b", "c", "d"]);
+  });
+
+  it("returns topological order for a diamond DAG", () => {
+    const fg = buildDiamondDag();
+    const order = topologicalOrder(fg);
+    expect(order[0]).toBe("top");
+    expect(order[3]).toBe("bottom");
+    expect(order).toContain("left");
+    expect(order).toContain("right");
+  });
+
+  it("returns empty array for empty graph", () => {
+    const fg = new FlowGraph();
+    expect(topologicalOrder(fg)).toEqual([]);
+  });
+
+  it("returns single node for graph with one node", () => {
+    const fg = new FlowGraph();
+    fg.addNode("only", { name: "only" });
+    expect(topologicalOrder(fg)).toEqual(["only"]);
+  });
+
+  it("throws CycleError when graph has cycles", () => {
+    const fg = new FlowGraph();
+    fg.graph.addNode("a");
+    fg.graph.addNode("b");
+    fg.graph.addNode("c");
+    fg.graph.addEdgeWithKey("a->b", "a", "b");
+    fg.graph.addEdgeWithKey("b->c", "b", "c");
+    fg.graph.addEdgeWithKey("c->a", "c", "a");
+    expect(() => topologicalOrder(fg)).toThrow(CycleError);
+  });
+});
+
+describe("parallelGroups (analysis)", () => {
+  it("groups chain nodes into sequential groups", () => {
+    const fg = buildChainDag();
+    const groups = parallelGroups(fg);
+    expect(groups).toEqual([["a"], ["b"], ["c"], ["d"]]);
+  });
+
+  it("groups diamond DAG correctly", () => {
+    const fg = buildDiamondDag();
+    const groups = parallelGroups(fg);
+    expect(groups.length).toBe(3);
+    expect(groups[0]).toEqual(["top"]);
+    expect(groups[1]!.sort()).toEqual(["left", "right"]);
+    expect(groups[2]).toEqual(["bottom"]);
+  });
+
+  it("groups wide DAG with root and leaves", () => {
+    const fg = buildWideDag();
+    const groups = parallelGroups(fg);
+    expect(groups.length).toBe(2);
+    expect(groups[0]).toEqual(["root"]);
+    expect(groups[1]!.sort()).toEqual(["x", "y", "z"]);
+  });
+
+  it("groups disconnected DAG correctly", () => {
+    const fg = buildDisconnectedDag();
+    const groups = parallelGroups(fg);
+    expect(groups.length).toBe(2);
+    expect(groups[0]!.sort()).toEqual(["a", "c"]);
+    expect(groups[1]).toEqual(["b"]);
+  });
+
+  it("returns empty array for empty graph", () => {
+    const fg = new FlowGraph();
+    expect(parallelGroups(fg)).toEqual([]);
+  });
+
+  it("returns single group for single node with no edges", () => {
+    const fg = new FlowGraph();
+    fg.addNode("only", { name: "only" });
+    expect(parallelGroups(fg)).toEqual([["only"]]);
+  });
+
+  it("throws CycleError when graph has cycles", () => {
+    const fg = new FlowGraph();
+    fg.graph.addNode("a");
+    fg.graph.addNode("b");
+    fg.graph.addEdgeWithKey("a->b", "a", "b");
+    fg.graph.addEdgeWithKey("b->a", "b", "a");
+    expect(() => parallelGroups(fg)).toThrow(CycleError);
+  });
+});
+
+describe("criticalPath (analysis)", () => {
+  it("returns full chain for a chain DAG", () => {
+    const fg = buildChainDag();
+    expect(criticalPath(fg)).toEqual(["a", "b", "c", "d"]);
+  });
+
+  it("returns a longest path for diamond DAG", () => {
+    const fg = buildDiamondDag();
+    const path = criticalPath(fg);
+    expect(path.length).toBe(3);
+    expect(path[0]).toBe("top");
+    expect(path[2]).toBe("bottom");
+    expect(path[1] === "left" || path[1] === "right").toBe(true);
+  });
+
+  it("returns single node for graph with one node", () => {
+    const fg = new FlowGraph();
+    fg.addNode("only", { name: "only" });
+    expect(criticalPath(fg)).toEqual(["only"]);
+  });
+
+  it("returns empty array for empty graph", () => {
+    const fg = new FlowGraph();
+    expect(criticalPath(fg)).toEqual([]);
+  });
+
+  it("returns correct path for wide DAG", () => {
+    const fg = buildWideDag();
+    const path = criticalPath(fg);
+    expect(path.length).toBe(2);
+    expect(path[0]).toBe("root");
+  });
+
+  it("throws CycleError when graph has cycles", () => {
+    const fg = new FlowGraph();
+    fg.graph.addNode("a");
+    fg.graph.addNode("b");
+    fg.graph.addEdgeWithKey("a->b", "a", "b");
+    fg.graph.addEdgeWithKey("b->a", "b", "a");
+    expect(() => criticalPath(fg)).toThrow(CycleError);
+  });
+});
+
+describe("reachableFrom (analysis)", () => {
+  it("returns all reachable nodes from a single start node", () => {
+    const fg = buildChainDag();
+    expect(reachableFrom(fg, ["a"])).toEqual(new Set(["a", "b", "c", "d"]));
+  });
+
+  it("returns only the start node if it is a leaf", () => {
+    const fg = buildChainDag();
+    expect(reachableFrom(fg, ["d"])).toEqual(new Set(["d"]));
+  });
+
+  it("returns union of reachable nodes from multiple start nodes", () => {
+    const fg = buildDiamondDag();
+    expect(reachableFrom(fg, ["left", "right"])).toEqual(new Set(["left", "right", "bottom"]));
+  });
+
+  it("returns empty set for empty input", () => {
+    const fg = buildChainDag();
+    expect(reachableFrom(fg, [])).toEqual(new Set());
+  });
+
+  it("returns full reachable set from root in diamond", () => {
+    const fg = buildDiamondDag();
+    expect(reachableFrom(fg, ["top"])).toEqual(new Set(["top", "left", "right", "bottom"]));
+  });
+});
+
+describe("ancestors (analysis)", () => {
+  it("returns all ancestors for a node in a chain", () => {
+    const fg = buildChainDag();
+    expect(ancestors(fg, "d")).toEqual(["c", "b", "a"]);
+  });
+
+  it("returns all ancestors for a node in a diamond DAG", () => {
+    const fg = buildDiamondDag();
+    const anc = ancestors(fg, "bottom");
+    expect(anc).toContain("left");
+    expect(anc).toContain("right");
+    expect(anc).toContain("top");
+    expect(anc.length).toBe(3);
+  });
+
+  it("returns empty array for a root node", () => {
+    const fg = buildChainDag();
+    expect(ancestors(fg, "a")).toEqual([]);
+  });
+
+  it("throws NodeNotFoundError for missing node", () => {
+    const fg = new FlowGraph();
+    expect(() => ancestors(fg, "missing")).toThrow(NodeNotFoundError);
+  });
+});
+
+describe("descendants (analysis)", () => {
+  it("returns all descendants for a node in a chain", () => {
+    const fg = buildChainDag();
+    expect(descendants(fg, "a")).toEqual(["b", "c", "d"]);
+  });
+
+  it("returns all descendants for a node in a diamond DAG", () => {
+    const fg = buildDiamondDag();
+    const desc = descendants(fg, "top");
+    expect(desc).toContain("left");
+    expect(desc).toContain("right");
+    expect(desc).toContain("bottom");
+    expect(desc.length).toBe(3);
+  });
+
+  it("returns empty array for a leaf node", () => {
+    const fg = buildChainDag();
+    expect(descendants(fg, "d")).toEqual([]);
+  });
+
+  it("throws NodeNotFoundError for missing node", () => {
+    const fg = new FlowGraph();
+    expect(() => descendants(fg, "missing")).toThrow(NodeNotFoundError);
+  });
+});