feat(asyncDropUntilOnce): add asyncDropUntilOnce function

Author: djcsdy

index.test.ts

@@ -2,6 +2,7 @@ import type {ExecutionContext} from "ava";
 import test from "ava";
 import {
     asyncDropOnce,
+    asyncDropUntilOnce,
     asyncDropWhileOnce,
     asyncEmptyOnce,
     asyncInitialOnce,
@@ -256,3 +257,30 @@ test("asyncDropWhileOnce", async t => {
         [4, 3, 2, 1]
     );
 });
+
+test("asyncDropUntilOnce", async t => {
+    t.deepEqual(
+        await asyncToArrayOnce(asyncDropUntilOnce(asyncIterator([]), (_, i) => i >= 3)),
+        []
+    );
+    t.deepEqual(
+        await asyncToArrayOnce(asyncDropUntilOnce(asyncIterator([1, 2]), (_, i) => i >= 3)),
+        []
+    );
+    t.deepEqual(
+        await asyncToArrayOnce(
+            asyncDropUntilOnce(asyncIterator([1, 2, 3, 4, 5]), (_, i) => i >= 3)
+        ),
+        [4, 5]
+    );
+    t.deepEqual(
+        await asyncToArrayOnce(asyncDropUntilOnce(asyncIterator([1, 2, 3, 4, 5]), () => true)),
+        [1, 2, 3, 4, 5]
+    );
+    t.deepEqual(
+        await asyncToArrayOnce(
+            asyncDropUntilOnce(asyncIterator([1, 2, 3, 4, 3, 2, 1]), e => e >= 4)
+        ),
+        [4, 3, 2, 1]
+    );
+});

index.ts

@@ -395,3 +395,28 @@ export function asyncDropWhileOnceFn<T>(
 ): (iterator: AsyncIteratorLike<T>) => AsyncIterator<T> {
     return iterator => asyncDropWhileOnce(iterator, predicate);
 }
+
+export function asyncDropUntilOnce<T>(
+    iterator: AsyncIteratorLike<T>,
+    predicate: (element: T, index: number) => boolean | Promise<boolean>
+): AsyncIterator<T> {
+    const it = asyncIterator(iterator);
+    let i = 0;
+    const before = async (): Promise<IteratorResult<T>> => {
+        let element = await it.next();
+        while (element.done !== true && !(await predicate(element.value, i++))) {
+            element = await it.next();
+        }
+        next = during;
+        return element;
+    };
+    const during = async (): Promise<IteratorResult<T>> => it.next();
+    let next = before;
+    return {next: async () => next()};
+}
+
+export function asyncDropUntilOnceFn<T>(
+    predicate: (element: T, index: number) => boolean | Promise<boolean>
+): (iterator: AsyncIteratorLike<T>) => AsyncIterator<T> {
+    return iterator => asyncDropUntilOnce(iterator, predicate);
+}