feat(range): add validator for range

combinator.ts

@@ -2,6 +2,7 @@
 // This module is browser compatible.
 
 import { PropertyValidator } from "./validators/property.ts";
+import { RangeValidator } from "./validators/range.ts";
 import { FixedArrayValidator } from "./validators/array/fixed_array.ts";
 import { DictionaryValidator } from "./validators/object/dictionary.ts";
 import { OptionalValidator } from "./validators/object/optional.ts";
@@ -48,6 +49,7 @@ export const ne = /* @__PURE__ */ lazy(InequalityValidator);
 export const not = /* @__PURE__ */ lazy(NotValidator);
 export const or = /* @__PURE__ */ lazy(OrValidator);
 export const and = /* @__PURE__ */ lazy(AndValidator);
+export const between = /* @__PURE__ */ lazy(RangeValidator);
 
 // known
 export const property = /* @__PURE__ */ lazy(PropertyValidator);

mod.ts

@@ -16,6 +16,7 @@ export {
 } from "./validation.ts";
 export {
   and,
+  between,
   bigint,
   boolean,
   count,

validators/range.ts

@@ -0,0 +1,39 @@
+// Copyright 2023-latest Tomoki Miyauchi. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { isInRange, shouldBeBut } from "./utils.ts";
+import { ScalarValidator } from "../utils.ts";
+
+export class RangeValidator<In> extends ScalarValidator<In> {
+  #range!: [In, In];
+
+  get range(): [In, In] {
+    return this.#range;
+  }
+
+  set range(range) {
+    if (range[1] <= range[0]) {
+      throw RangeError("max should be greater than min");
+    }
+
+    this.#range = range;
+  }
+
+  /**
+   * @throws {RangeError} If {@link max} less than or equal to {@link min}.
+   */
+  constructor(min: In, max: In) {
+    super();
+    super.expect(shouldBeBut);
+
+    this.range = [min, max];
+  }
+
+  override is(input: In): input is In {
+    return isInRange(input, this.range);
+  }
+
+  override toString(): string {
+    return `between ${this.range[0]} and ${this.range[1]}`;
+  }
+}

validators/utils.ts

@@ -31,3 +31,17 @@ export function shouldBeBut(
 ): string {
   return interpolate(error.should_be_but, [this, input]);
 }
+
+/**
+ * @throws {RangeError} If max less than or equal to min.
+ */
+export function isInRange<T>(
+  input: T,
+  range: readonly [mix: T, max: T],
+): boolean {
+  const [min, max] = range;
+
+  if (max <= min) throw new RangeError("max should be greater then min");
+
+  return min <= input && input <= max;
+}