feat(excludeFirst): add excludeFirst function

Author: djcsdy

index.test.ts

@@ -6,6 +6,7 @@ import {
     empty,
     equal,
     exclude,
+    excludeFirst,
     filter,
     initial,
     last,
@@ -158,3 +159,10 @@ test("exclude", async t => {
         [3, 4, 3]
     );
 });
+
+test("excludeFirst", async t => {
+    t.deepEqual(
+        await toArray(excludeFirst(asyncIterable([1, 2, 3, 4, 3, 2, 1]), n => n > 2)),
+        [1, 2, 4, 3, 2, 1]
+    );
+});

index.ts

@@ -453,3 +453,38 @@ export function excludeFn<T>(
 }
 
 export const asyncExcludeFn = exclude;
+
+export async function* excludeFirst<T>(
+    iterable: AsyncIterableLike<T>,
+    predicate: (element: T, index: number) => boolean | Promise<boolean>
+): AsyncIterable<T> {
+    const iterator = asyncIterator(iterable);
+    let result = await iterator.next();
+
+    for (let i = 0; result.done !== true; ++i) {
+        if (await predicate(result.value, i)) {
+            break;
+        }
+        yield result.value;
+        result = await iterator.next();
+    }
+
+    if (result.done !== true) {
+        result = await iterator.next();
+    }
+
+    while (result.done !== true) {
+        yield result.value;
+        result = await iterator.next();
+    }
+}
+
+export const asyncExcludeFirst = excludeFirst;
+
+export function excludeFirstFn<T>(
+    predicate: (element: T, index: number) => boolean | Promise<boolean>
+): (iterable: AsyncIterableLike<T>) => AsyncIterable<T> {
+    return iterable => excludeFirst(iterable, predicate);
+}
+
+export const asyncExcludeFirstFn = excludeFirstFn;