feat(type): add validator for value type

validators/type.ts

@@ -0,0 +1,43 @@
+// Copyright 2023-latest Tomoki Miyauchi. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { Assert, Display } from "../types.ts";
+import { AssertiveScalarValidator, format } from "../utils.ts";
+import error from "./error.json" assert { type: "json" };
+
+export type Type = keyof TypeMap;
+
+export interface TypeMap {
+  bigint: bigint;
+  boolean: boolean;
+  // deno-lint-ignore ban-types
+  function: Function;
+  number: number;
+  // deno-lint-ignore ban-types
+  object: object | null;
+  string: string;
+  symbol: symbol;
+  undefined: undefined;
+}
+
+export class TypeValidator<T extends Type>
+  extends AssertiveScalarValidator<unknown, TypeMap[T]> {
+  declare [Assert.symbol]: TypeMap[T];
+  constructor(public of: T) {
+    super();
+    super.expect(message);
+  }
+
+  override is(input: unknown): input is TypeMap[T] {
+    // deno-lint-ignore valid-typeof
+    return typeof input === this.of;
+  }
+
+  toString(): string {
+    return `type of ${this.of}`;
+  }
+}
+
+export function message(this: Display, { input }: { input: unknown }): string {
+  return format(error.should_be, this, typeof input);
+}