chore: Extract Map, Gutter and add-separator from monolith

Signed-off-by: Iku-turso <mikko.aspiala@gmail.com>

packages/utility-features/utilities/index.ts

@@ -43,3 +43,4 @@ export * from "./src/types";
 export * from "./src/union-env-path";
 export * from "./src/wait";
 export * from "./src/with-concurrency-limit";
+export * from "./src/add-separator/add-separator";

packages/utility-features/utilities/src/add-separator/add-separator.test.ts

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) OpenLens Authors. All rights reserved.
+ * Licensed under MIT License. See LICENSE in root directory for more information.
+ */
+import { addSeparator } from "./add-separator";
+
+describe("add-separator", () => {
+  it("given multiple items, adds separators", () => {
+    const items = ["first", "second", "third"];
+
+    const actual = addSeparator((left, right) => `separator-between-${left}-and-${right}`, items);
+
+    expect(actual).toEqual([
+      "first",
+      "separator-between-first-and-second",
+      "second",
+      "separator-between-second-and-third",
+      "third",
+    ]);
+  });
+
+  it("given multiple items including falsy ones, adds separators", () => {
+    const items = [false, undefined, null, NaN];
+
+    const actual = addSeparator((left, right) => `separator-between-${left}-and-${right}`, items);
+
+    expect(actual).toEqual([
+      false,
+      "separator-between-false-and-undefined",
+      undefined,
+      "separator-between-undefined-and-null",
+      null,
+      "separator-between-null-and-NaN",
+      NaN,
+    ]);
+  });
+
+  it("given no items, does not add separator", () => {
+    const items: any[] = [];
+
+    const actual = addSeparator(() => "separator", items);
+
+    expect(actual).toEqual([]);
+  });
+
+  it("given one item, does not add separator", () => {
+    const items = ["first"];
+
+    const actual = addSeparator(() => "separator", items);
+
+    expect(actual).toEqual(["first"]);
+  });
+});

packages/utility-features/utilities/src/add-separator/add-separator.ts

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) OpenLens Authors. All rights reserved.
+ * Licensed under MIT License. See LICENSE in root directory for more information.
+ */
+
+export type GetSeparator<Item, Separator> = (left: Item, right: Item) => Separator;
+
+export const addSeparator = <Item, Separator>(
+  getSeparator: GetSeparator<Item, Separator>,
+  items: Item[],
+) => items.flatMap(toSeparatedTupleUsing(getSeparator));
+
+const toSeparatedTupleUsing =
+  <Item, Separator>(getSeparator: GetSeparator<Item, Separator>) =>
+    (leftItem: Item, index: number, arr: Item[]) => {
+      const itemIsLast = arr.length === index + 1;
+
+      if (itemIsLast) {
+        return [leftItem];
+      }
+
+      const rightItem = arr[index + 1];
+      const separator = getSeparator(leftItem, rightItem);
+
+      return [leftItem, separator];
+    };