Merge pull request #20 from Baek2back/python/zip-longest

feat(zip-longest): naive implementation

packages/python/src/itertools/index.ts

@@ -9,3 +9,4 @@ export * from "./filterfalse";
 export * from "./islice";
 export * from "./repeat";
 export * from "./starmap";
+export * from "./zipLongest";

packages/python/src/itertools/zipLongest.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, it } from "vitest";
+import { zipLongest } from "./zipLongest";
+
+describe("zipLongest", () => {
+  it("zipLongest with empty iterable", () => {
+    const result = [...zipLongest([], [])];
+    expect(result).toEqual([]);
+  });
+  it("should zip until the longest value", () => {
+    const result = [...zipLongest("ABCD", "xy", { fillvalue: "-" })];
+    expect(result).toEqual([
+      ["A", "x"],
+      ["B", "y"],
+      ["C", "-"],
+      ["D", "-"],
+    ]);
+  });
+
+  it("should zip fill with undefined", () => {
+    const result = [...zipLongest("", "ABCD")];
+    expect(result).toEqual([
+      [undefined, "A"],
+      [undefined, "B"],
+      [undefined, "C"],
+      [undefined, "D"],
+    ]);
+  });
+});

packages/python/src/itertools/zipLongest.ts

@@ -0,0 +1,23 @@
+import { iter } from "../built-in";
+
+export function* zipLongest<T1, T2, D>(
+  xs: Iterable<T1>,
+  ys: Iterable<T2>,
+  options: { fillvalue?: D } = {},
+): IterableIterator<[T1 | D, T2 | D]> {
+  const { fillvalue } = options;
+  const [ixs, iys] = [iter(xs), iter(ys)];
+
+  while (true) {
+    const [x, y] = [ixs.next(), iys.next()];
+
+    if (x.done && y.done) {
+      return;
+    }
+
+    yield [
+      !x.done ? x.value : (fillvalue as D),
+      !y.done ? y.value : (fillvalue as D),
+    ];
+  }
+}