feat(element): add validator for element

validators/iterable/element.ts

@@ -0,0 +1,26 @@
+// Copyright 2023-latest Tomoki Miyauchi. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { fromPath, partialR } from "../../utils.ts";
+import { entries, map } from "../../iter_utils.ts";
+import {
+  Assert,
+  AssertiveValidator,
+  Validation,
+  ValidationError,
+} from "../../types.ts";
+
+export class ElementValidator<In = unknown, In_ extends In = In>
+  implements AssertiveValidator<Iterable<In>, Iterable<In_>> {
+  declare [Assert.symbol]: Iterable<In_>;
+  constructor(public readonly validator: Validation<In, In_>) {}
+
+  *validate(input: Iterable<In>): Iterable<ValidationError> {
+    for (const [i, el] of entries(input)) {
+      const iterable = this.validator.validate(el);
+      const createError = partialR(fromPath, `${i}`);
+
+      yield* map(iterable, createError);
+    }
+  }
+}