Update asyncFilter

utils.ts

@@ -81,14 +81,25 @@ export function try_remove_sync(
     }
 }
 
-export async function asyncFilter<T>(
-    arr: T[],
-    callback: (element: T, index: number, array: T[]) => Promise<boolean>,
+const fail = Symbol();
+
+export async function asyncFilter<T, V>(
+    arr: ArrayLike<T>,
+    callback: (
+        this: V | undefined,
+        element: T,
+        index: number,
+        array: ArrayLike<T>,
+    ) => Promise<boolean>,
+    thisArg?: V,
 ): Promise<T[]> {
-    const fail = Symbol();
     const t = <[T][]> (await Promise.all(
-        arr.map(async (item, index, array) =>
-            (await callback(item, index, array)) ? [item] : fail
+        map(
+            arr,
+            async (item, index, array) =>
+                (await callback.apply(thisArg, [item, index, array]))
+                    ? [item]
+                    : fail,
         ),
     )).filter((i) => i !== fail);
     return t.map((t) => t[0]);
@@ -231,3 +242,20 @@ export async function asyncEvery<T, V>(
     }
     return true;
 }
+
+export function map<T, S, V>(
+    arr: ArrayLike<T>,
+    callback: (
+        this: S | undefined,
+        element: T,
+        index: number,
+        array: ArrayLike<T>,
+    ) => V,
+    thisArg?: S,
+) {
+    const re: V[] = [];
+    for (let i = 0; i < arr.length; i++) {
+        re.push(callback.apply(thisArg, [arr[i], i, arr]));
+    }
+    return re;
+}

utils_test.ts

@@ -7,6 +7,7 @@ import {
     asyncForEach,
     calFileMd5,
     filterFilename,
+    map,
     promiseState,
     PromiseStatus,
     sleep,
@@ -47,11 +48,19 @@ Deno.test("asyncFilter_test", async () => {
     });
     assertEquals(r, [3]);
     const e = [new Promise<number>((res) => setTimeout(() => res(100), 100))];
-    const v = await asyncFilter(e, async (t) => {
-        const s = await promiseState(t);
+    const v = await asyncFilter(e, async function (d) {
+        assertEquals(this, t);
+        const s = await promiseState(d);
         return s.status === PromiseStatus.Pending;
-    });
+    }, t);
     assertEquals(v, e);
+    const e2 = { 0: e[0], length: 1 };
+    const v2 = await asyncFilter(e2, async function (d) {
+        assertEquals(this, t);
+        const s = await promiseState(d);
+        return s.status === PromiseStatus.Pending;
+    }, t);
+    assertEquals(v, v2);
     await Promise.allSettled(e);
 });
 
@@ -128,3 +137,13 @@ Deno.test("asyncEvery_test", async () => {
         false,
     );
 });
+
+Deno.test("map_test", () => {
+    const arr = { 0: 1, 1: 2, length: 2 };
+    const d = { d: 1 };
+    const re = map(arr, function (n) {
+        assertEquals(this, d);
+        return n + 2;
+    }, d);
+    assertEquals(re, [3, 4]);
+});