Add remove API

src/set-array.ts

@@ -63,3 +63,20 @@ export function pop<T extends Key>(setarr: SetArray<T>): void {
   const last = array.pop()!;
   indexes[last] = undefined;
 }
+
+/**
+ * Removes the key, if it exists in the set.
+ */
+export function remove<T extends Key>(setarr: SetArray<T>, key: T): void {
+  const index = get(setarr, key);
+  if (index === undefined) return;
+
+  const { array, _indexes: indexes } = cast(setarr);
+  for (let i = index + 1; i < array.length; i++) {
+    const k = array[i];
+    array[i - 1] = k;
+    indexes[k]!--;
+  }
+  indexes[key] = undefined;
+  array.pop();
+}

test/set-array.test.ts

@@ -1,4 +1,4 @@
-import { SetArray, get, put, pop } from '../src/set-array';
+import { SetArray, get, put, pop, remove } from '../src/set-array';
 import { strict as assert } from 'assert';
 
 describe('SetArray', () => {
@@ -111,4 +111,59 @@ describe('SetArray', () => {
       assert.equal(get(array, 'foo'), 0);
     });
   });
+
+  describe('remove()', () => {
+    it('removes item from array', () => {
+      const array = new SetArray();
+
+      put(array, 'test');
+      put(array, 'foo');
+      put(array, 'bar');
+
+      remove(array, 'foo');
+      assert.deepEqual(array.array, ['test', 'bar']);
+      remove(array, 'bar');
+      assert.deepEqual(array.array, ['test']);
+      remove(array, 'test');
+      assert.deepEqual(array.array, []);
+    });
+
+    it('unsets the key', () => {
+      const array = new SetArray();
+
+      put(array, 'test');
+      remove(array, 'test');
+      assert.equal(get(array, 'test'), undefined);
+    });
+
+    it('updates indexes of following keys', () => {
+      const array = new SetArray();
+
+      put(array, 'test');
+      put(array, 'foo');
+      put(array, 'bar');
+
+      remove(array, 'foo');
+      assert.equal(get(array, 'test'), 0);
+      assert.equal(get(array, 'bar'), 1);
+    });
+
+    it('putting afterwards writes to array at old index', () => {
+      const array = new SetArray();
+
+      put(array, 'test');
+      remove(array, 'test');
+      put(array, 'foo');
+      assert.deepEqual(array.array, ['foo']);
+    });
+
+    it('getting after put gets old key ', () => {
+      const array = new SetArray();
+
+      put(array, 'test');
+      remove(array, 'test');
+      put(array, 'foo');
+      assert.equal(get(array, 'foo'), 0);
+    });
+  });
 });