feat(single): add validator for single item

_tools/meta.ts

@@ -52,6 +52,11 @@ export const makeOptions = (version: string): BuildOptions => ({
       version: "1.3.1",
       subPath: "iterable/is_not_empty.js",
     },
+    "https://deno.land/x/isx@1.3.1/iterable/is_single.ts": {
+      name: "@miyauci/isx",
+      version: "1.3.1",
+      subPath: "iterable/is_single.js",
+    },
     "https://deno.land/x/isx@1.3.1/is_string.ts": {
       name: "@miyauci/isx",
       version: "1.3.1",

combinator.ts

@@ -16,14 +16,15 @@ import { UniqueValidator } from "./validators/iterable/unique.ts";
 import { MaxCountValidator } from "./validators/iterable/max_count.ts";
 import { MinCountValidator } from "./validators/iterable/min_count.ts";
 import { NonEmptyValidator } from "./validators/iterable/non_empty.ts";
-import { AndValidator } from "./validators/operators/and.ts";
+import { SingleValidator } from "./validators/iterable/single.ts";
 import { EqualityValidator } from "./validators/operators/eq.ts";
 import { LessThenValidator } from "./validators/operators/lt.ts";
 import { LessThenOrEqualValidator } from "./validators/operators/lte.ts";
 import { GreaterThenValidator } from "./validators/operators/gt.ts";
 import { GreaterThenOrEqualValidator } from "./validators/operators/gte.ts";
 import { InequalityValidator } from "./validators/operators/inequality.ts";
 import { InstanceValidator } from "./validators/operators/instanceof.ts";
+import { AndValidator } from "./validators/operators/and.ts";
 import { NotValidator } from "./validators/operators/not.ts";
 import { OrValidator } from "./validators/operators/or.ts";
 import { TypeValidator } from "./validators/operators/typeof.ts";
@@ -64,6 +65,7 @@ export const item = /* @__PURE__ */ lazy(ItemValidator);
 export const maxCount = /* @__PURE__ */ lazy(MaxCountValidator);
 export const minCount = /* @__PURE__ */ lazy(MinCountValidator);
 export const nonEmpty = /* @__PURE__ */ new NonEmptyValidator();
+export const single = /* @__PURE__ */ new SingleValidator();
 export const unique = /* @__PURE__ */ new UniqueValidator();
 
 // number

deps.ts

@@ -3,6 +3,7 @@
 
 export { isEmpty } from "https://deno.land/x/isx@1.3.1/iterable/is_empty.ts";
 export { isNotEmpty } from "https://deno.land/x/isx@1.3.1/iterable/is_not_empty.ts";
+export { isSingle } from "https://deno.land/x/isx@1.3.1/iterable/is_single.ts";
 export { isNonNullable } from "https://deno.land/x/isx@1.3.1/is_non_nullable.ts";
 export { isString } from "https://deno.land/x/isx@1.3.1/is_string.ts";
 export { isPositiveNumber } from "https://deno.land/x/isx@1.3.1/number/is_positive_number.ts";

validators/iterable/single.ts

@@ -0,0 +1,15 @@
+// Copyright 2023-latest Tomoki Miyauchi. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { shouldBe } from "../utils.ts";
+import { isSingle } from "../../deps.ts";
+import { display, ScalarValidator } from "../../utils.ts";
+
+@display("single")
+export class SingleValidator extends ScalarValidator<Iterable<unknown>> {
+  constructor() {
+    super();
+    super.expect(shouldBe);
+  }
+  override is = isSingle;
+}