feat(property): add validator for property

combinator.ts

@@ -3,6 +3,7 @@
 
 import { TypeValidator } from "./validators/type.ts";
 import { InstanceValidator } from "./validators/instance.ts";
+import { PropertyValidator } from "./validators/property.ts";
 import { DictionaryValidator } from "./validators/object/dictionary.ts";
 import { OptionalValidator } from "./validators/object/optional.ts";
 import { NullishValidator } from "./validators/nullish.ts";
@@ -36,6 +37,9 @@ export const lt = /* @__PURE__ */ lazy(LessValidator);
 export const gt = /* @__PURE__ */ lazy(GreaterValidator);
 export const and = /* @__PURE__ */ lazy(AndValidator);
 
+// known
+export const property = /* @__PURE__ */ lazy(PropertyValidator);
+
 // Date
 export const validDate = /* @__PURE__ */ new ValidDateValidator();
 

mod.ts

@@ -23,6 +23,7 @@ export {
   optional,
   pattern,
   positive,
+  property,
   string,
   type,
   unique,

validators/property.ts

@@ -0,0 +1,35 @@
+// deno-lint-ignore-file ban-types
+// Copyright 2023-latest Tomoki Miyauchi. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { curryR, fromPath } from "../utils.ts";
+import { map } from "../iter_utils.ts";
+import {
+  Assert,
+  AssertiveValidator,
+  Validation,
+  ValidationError,
+  Validator,
+} from "../types.ts";
+
+export class PropertyValidator<In_ extends string = string>
+  implements AssertiveValidator<{}, Record<In_, unknown>> {
+  declare [Assert.symbol]: Record<In_, unknown>;
+  validator: Validation<string>;
+
+  constructor(validator: Validation<string, In_>) {
+    this.validator = validator as Validator<string>;
+  }
+
+  *validate(input: {}): Iterable<ValidationError> {
+    for (const key in input) {
+      const createError = curryR(fromPath, key);
+
+      yield* map(this.validator.validate(key), createError);
+    }
+  }
+
+  toString(): string {
+    return `key of ${this.validator}`;
+  }
+}