Add TypeScript goody for pre-order traversal of an N-ary tree (#518)

Closes #396.

Author: skdthread

workspaces/adventure-pack/goodies/typescript/traversePreOrderNAry/index.test.ts

@@ -0,0 +1,61 @@
+import { describe, expect, it } from "@jest/globals";
+
+import { traversePreOrderNAry } from "./index.ts";
+
+type Node = { val: number; children: Node[] };
+
+describe("traversePreOrderNAry", () => {
+  it("yields nothing for null/undefined root", () => {
+    expect([...traversePreOrderNAry(null)]).toStrictEqual([]);
+    expect([...traversePreOrderNAry(undefined)]).toStrictEqual([]);
+  });
+
+  it("yields root only for single node", () => {
+    const root: Node = { val: 1, children: [] };
+    expect([...traversePreOrderNAry(root)].map((n) => n.val)).toStrictEqual([
+      1,
+    ]);
+  });
+
+  it("visits parent before children", () => {
+    const root: Node = {
+      val: 1,
+      children: [
+        {
+          val: 2,
+          children: [
+            { val: 5, children: [] },
+            { val: 6, children: [] },
+          ],
+        },
+        { val: 3, children: [] },
+        {
+          val: 4,
+          children: [{ val: 7, children: [] }],
+        },
+      ],
+    };
+    expect([...traversePreOrderNAry(root)].map((n) => n.val)).toStrictEqual([
+      1, 2, 5, 6, 3, 4, 7,
+    ]);
+  });
+
+  it("traverses deeper trees in pre-order", () => {
+    const root: Node = {
+      val: 1,
+      children: [
+        {
+          val: 2,
+          children: [
+            { val: 4, children: [] },
+            { val: 5, children: [] },
+          ],
+        },
+        { val: 3, children: [] },
+      ],
+    };
+    expect([...traversePreOrderNAry(root)].map((n) => n.val)).toStrictEqual([
+      1, 2, 4, 5, 3,
+    ]);
+  });
+});

workspaces/adventure-pack/goodies/typescript/traversePreOrderNAry/index.ts

@@ -0,0 +1,18 @@
+export function* traversePreOrderNAry<T extends { children: T[] }>(
+  root: T | null | undefined,
+): Generator<T, void, void> {
+  if (root == null) {
+    return;
+  }
+
+  const stack: T[] = [root];
+
+  do {
+    const node = stack.pop()!;
+    yield node;
+    // TODO: add an Array.prototype.valuesReversed() goody and use it here
+    for (let i = node.children.length - 1; i >= 0; --i) {
+      stack.push(node.children[i]);
+    }
+  } while (stack.length > 0);
+}

workspaces/adventure-pack/src/app/__tests__/__snapshots__/equip-test.ts.snap

@@ -2724,6 +2724,31 @@ function* traversePreOrder(root) {
 /////////////////////////// END ADVENTURE PACK CODE ////////////////////////////"
 `;
 
+exports[`App can equip single goody: JavaScript traversePreOrderNAry 1`] = `
+"////////////////////////// BEGIN ADVENTURE PACK CODE ///////////////////////////
+// Adventure Pack commit fake-commit-hash
+// Running at: https://example.com/
+
+function* traversePreOrderNAry(root) {
+  if (root == null) {
+    return;
+  }
+
+  const stack = [root];
+
+  do {
+    const node = stack.pop();
+    yield node;
+    // TODO: add an Array.prototype.valuesReversed() goody and use it here
+    for (let i = node.children.length - 1; i >= 0; --i) {
+      stack.push(node.children[i]);
+    }
+  } while (stack.length > 0);
+}
+
+/////////////////////////// END ADVENTURE PACK CODE ////////////////////////////"
+`;
+
 exports[`App can equip single goody: Kotlin gcd(Int,Int) 1`] = `
 "////////////////////////// BEGIN ADVENTURE PACK CODE ///////////////////////////
 // Adventure Pack commit fake-commit-hash
@@ -5509,3 +5534,30 @@ function* traversePreOrder<
 
 /////////////////////////// END ADVENTURE PACK CODE ////////////////////////////"
 `;
+
+exports[`App can equip single goody: TypeScript traversePreOrderNAry 1`] = `
+"////////////////////////// BEGIN ADVENTURE PACK CODE ///////////////////////////
+// Adventure Pack commit fake-commit-hash
+// Running at: https://example.com/
+
+function* traversePreOrderNAry<T extends { children: T[] }>(
+  root: T | null | undefined,
+): Generator<T, void, void> {
+  if (root == null) {
+    return;
+  }
+
+  const stack: T[] = [root];
+
+  do {
+    const node = stack.pop()!;
+    yield node;
+    // TODO: add an Array.prototype.valuesReversed() goody and use it here
+    for (let i = node.children.length - 1; i >= 0; --i) {
+      stack.push(node.children[i]);
+    }
+  } while (stack.length > 0);
+}
+
+/////////////////////////// END ADVENTURE PACK CODE ////////////////////////////"
+`;

workspaces/adventure-pack/src/app/__tests__/__snapshots__/render-test.ts.snap

@@ -1499,6 +1499,25 @@ exports[`App can render goody: JavaScript traversePreOrder 1`] = `
 }"
 `;
 
+exports[`App can render goody: JavaScript traversePreOrderNAry 1`] = `
+"export function* traversePreOrderNAry(root) {
+  if (root == null) {
+    return;
+  }
+
+  const stack = [root];
+
+  do {
+    const node = stack.pop();
+    yield node;
+    // TODO: add an Array.prototype.valuesReversed() goody and use it here
+    for (let i = node.children.length - 1; i >= 0; --i) {
+      stack.push(node.children[i]);
+    }
+  } while (stack.length > 0);
+}"
+`;
+
 exports[`App can render goody: Kotlin gcd(Int,Int) 1`] = `
 "package gcd_int_int
 
@@ -3159,3 +3178,24 @@ exports[`App can render goody: TypeScript traversePreOrder 1`] = `
   } while (stack.length > 0);
 }"
 `;
+
+exports[`App can render goody: TypeScript traversePreOrderNAry 1`] = `
+"export function* traversePreOrderNAry<T extends { children: T[] }>(
+  root: T | null | undefined,
+): Generator<T, void, void> {
+  if (root == null) {
+    return;
+  }
+
+  const stack: T[] = [root];
+
+  do {
+    const node = stack.pop()!;
+    yield node;
+    // TODO: add an Array.prototype.valuesReversed() goody and use it here
+    for (let i = node.children.length - 1; i >= 0; --i) {
+      stack.push(node.children[i]);
+    }
+  } while (stack.length > 0);
+}"
+`;